TW200840875A - Free-cutting steel excellent in manufacturability - Google Patents

Abstract

The invention provides free-cutting steel which is excellent in machinability and little erodes a plate refractory of a sliding nozzle for continuous casting and which is protected from surface deterioration in hot rolling by virtue its exhibiting excellent ductility in hot rolling. A free-cutting steel which contains by mass C: 0.005 to 0.2%, Si: 0.001 to 0.5%, Mn:0.3 to 3.0%, P: 0.001 to 0.2%, S: 0.30 to 0.60%, B: 0.0003 to 0.015%, O: 0.005 to 0.012%, Ca: 0.0001 to 0.0010%, and Al: = 0.01%, with the N content satisfying the relationships: N = 0.0020% and 1.3OE - 0.0100 = N = 1.3OE + 0.0034 and with the balance being Fe and unavoidable impurities, characterized in that in a section of the steel perpendicular to the direction of rolling, the area of Mn0 of 0.5[mu]m or above in diameter of the equivalent circle is at most 15% based on the total area of all the Mn-containing inclusions.

Description

200840875 IX. OBJECTS OF THE INVENTION: TECHNICAL FIELD The present invention relates to a low carbon quick-cut steel which is used in automobiles or general machinery and which requires more machinability than a strong 5 degree characteristic, and particularly relates to a kind Rapidly-cut steel with excellent manufacturability, which has excellent machinability, good tool life, machined surface roughness and chip handling property during cutting, and dissolution of plate-shaped refractories of sliding nozzles for continuous casting Less, it has good ductility during hot rolling. BACKGROUND OF THE INVENTION A general machine or automobile system is manufactured by a combination of various parts, and from the viewpoint of accuracy and manufacturing efficiency, it is often necessary to undergo a cutting step in manufacturing. At this time, in order to reduce costs and improve production efficiency, it is also necessary to improve the machinability of 15 steel. Low-carbosulfur-based quick-cutting steel SUM23 or low-carbon sulfur-lead composite quick-cutting steel SUM24L was invented with special emphasis on machinability. Steel type. It has been known that in order to improve the machinability, a machinability improving element such as S or Pb can be added, but from the viewpoint of the consumer, Pb which causes an environmental burden is avoided, and thus it tends to be reduced in usage. In the case where Pb is not added, a method of forming a soft inclusion such as a sulfide containing MnS as a main component in a cutting environment to improve the cutting property is also used. However, the low-carbon sulfur-lead composite fast-cut steel SUM24L adds the same amount of S as the low-carbon sulfur-based quick-cut steel SUM23, so it is necessary to add more than the previous amount of S. However, adding a large amount of S will only make the sulfide with MnS as the main component 5 200840875 coarse, which will not effectively improve the machinability, and will make the matrix less brittle, with the falling off of the cutting edge and the separation of the chips. This phenomenon causes a problem that the roughness of the machined surface is deteriorated and the chip is not sufficiently separated, and the chip handling property is poor. Further, in the production steps such as rolling and forging, since the sulfide having 5 coarse MnS as a main component causes a fracture start point and causes many problems in production such as rolling and fatigue, there is a limit to increasing the amount of S. Moreover, the addition of - - s machinability enhancing elements such as Te, Bi, P, N, etc., can also improve the machinability to some extent, but it causes breakage and glimpses of surface properties during calendering or hot forging. Deterioration, it is best to avoid the addition of the aforementioned elements, because it is difficult to achieve both machinability and manufacturability. The method disclosed in Japanese Laid-Open Patent Publication No. H11-222646 discloses that a single 20 μm or more sulfide or a plurality of sulfides are connected in a straight line to form a sulfide group having a length of 20 μm or more or more in the field of view of the section imm2 in the rolling direction. More than one, thereby improving the chip handling property. However, the fact that 15 includes the manufacturing method does not mention that the low surface roughness (Sub μιη sulfide dispersion method) which is most effective for machinability is not expected to be effective in terms of its composition. In the prior art, the inclusions other than the sulfides have been used for the purpose of improving the machinability. For example, JP-A-H09-9840, JP-A-2001-329335, JP-A-2002-3991, JP-A-2000-178683 Use of Bulletin ΒΝ ^ Technology to improve machinability. For the purpose of improving the life of the tool, JP-A-2002-3991, JP-A-2000-178683, the purpose of which is to improve the chip handling property. Using the chemical composition of the scope of the examples disclosed in the aforementioned documents, 6 200840875 does not provide sufficient effects in improving the roughness of the machined surface. Specifically, if the BN cannot be finely dispersed in the steel to homogenize the substrate, the effect of improving the roughness of the machined surface cannot be obtained, but the above-mentioned technique is not described in the above patent documents. 5 The technique disclosed in the Japanese Patent Publication No. 2_176176 is also an example of using BN for the purpose of improving the secret and considering the balance with the amount of N added. However, • M can completely suppress (4) delay the production of money and ensure the machinability of the opposite f, _ material chemical composition balance, or control to inhibit the high affinity with the enzyme b, become the amount of oxide and increase the precipitation The method of the amount of BN is not prompted in the aforementioned technique 10. Japanese Laid-Open Patent Publication No. Hei 5-345951 is a technique for increasing the size of MnS by increasing the oxygen concentration in steel in order to improve machinability. However, in this technique, regarding the reduction of MnS due to k-Nan oxygen and the consequent deterioration of machinability, the foregoing technique does not mention, and the refractory melt loss or surface flaw increase, etc., 15 apparently deteriorates in manufacturability. Preventive measures are also not mentioned. Further, in JP-A-2001-329335, in order to improve the hot rolling property, a technique for suppressing intergranular embrittlement by precipitation of grain boundaries of BN has been proposed, and it has been proposed to limit the amount of N added to utilize the crystal of solid solution B. A technique for preventing intergranular boundary embrittlement. However, since the above technique only reduces the amount of N, the amount of solid solution N in the BT heating to the processing temperature region is not sufficiently considered to be sufficient, and the amount of solid solution N required for preventing enthalpy is insufficient. Moreover, since it is limited to N1' which is lower than the stoichiometric composition, the amount of bn required to increase the roughness of the machined surface is insufficient, and it cannot be compensated by other techniques that complement the above disadvantages, so that a good rough surface cannot be obtained. degree. 7 200840875 In addition, Japanese Laid-Open Patent Publication No. 2004-27297 proposes a technique for limiting the amount of oxygen in steel in order to reduce surface enthalpy. However, there is no mention of any method of controlling the amount of oxygen in the steel. Without special control in the de-oxygen low-carbon quick-cut steel, it is impossible to limit the amount of oxygen in the steel to prevent the generation of bismuth. 5 There have been cases where ca is added to improve the machinability of low-carbon quick-cut steel. For example, JP-A-2000-160284, but the specific effect of improving the machinability is not recorded, and the range of Ca addition is also relatively high. Wide range, and the range of addition amount which can effectively improve the machinability is not described. Further, when the low-carbon quick-cut steel to which B is added is produced by the continuous casting method, there is a problem that the plate-shaped refractory of the sliding nozzle is easily damaged, but no prior document has been found which is useful for solving the above problems. [Spray content] The present invention is a low carbon quick-cut 15 steel used in automobiles or general machinery, and the like, and the present invention provides a quick-cutting steel, which is particularly suitable for cutting and machining during cutting. Excellent in cutting property such as surface roughness and chip handling property. In addition, the plate-shaped teaching material of the sliding nozzle for continuous casting has less melt loss, and has good ductility during hot rolling, thereby preventing surface properties due to heat generation. Getting worse. 2〇 The cutting system separates the damage of the chips and how to promote the cutting system-heavy point. However, as described above, there is a limit to simply increasing the amount of S, and in order to achieve both machinability and manufacturability, it is necessary to consider the amount of the machinability improving element. ~ Therefore, it has been found that the ratio of B to N required to control the bonding N in the calendering temperature region and to control the BN required for obtaining machinability at room temperature for cutting can be achieved in order to improve the hot dryness. Hot rolling properties and machinability. Here, the solid solution N means the amount by which the amount of the compound N is subtracted from the total amount of N, and the compound N means the amount of N which is substantially BN. Since BN is solid-solved under heating in the calendering temperature region of 8 〇〇 to lioot, a large amount of the above-mentioned solid solution N is generated, and 5 10 15 20 is preferably calendered in order to reduce the amount of surface enthalpy generated, and it is necessary to reduce the temperature at the aforementioned temperature. The amount of solid solution N in the area. In addition, it has been found that in order to improve the yield of MnS which is easily consumed as an oxide in molten steel, and the yield of B as BN, the yieldability and hot rolling property are improved, and the phase is suppressed and suppressed. The material of the material of the material of the material must be reduced in the steel _

The present invention has been made based on the above findings, and the gist thereof is as follows. (1) - A kind of fast-cut steel with excellent manufacturability, with quality I C : 0.005~0.2%; 3 Yes··

Si : :ο·οοι 〜0.5〇/〇; Μη • 0.3 ^ ^3.0% ; Ρ : 0.001- -0.2% ; S : 0.30 ～ 0.60% ; B : 0.0003 ～0_015〇/〇; 0 : 0.005- -0.012 % ;

Ca : 〇·〇〇01~〇〇〇1〇%,··Α1^〇.〇ι〇/0 , 3 is Ν^〇·〇〇2〇% and satisfies 1 3χΒ—〇ΧΒ + 0.0034, and The rest is composed of & and unavoidable impurities. ·, 200828875 In addition, regarding the Mn0 in the steel, the area of the MnO having an area equivalent diameter of 〇.5μιη or more in the cross section perpendicular to the rolling direction of the steel material The area of the inclusions relative to the full Μ-based system is 丨5% or less. (2) A fast-cut steel with excellent manufacturability, such as steel of (1), with respect to a sulfide having 5 MnS as a main component, in a section perpendicular to the rolling direction of the steel, the equivalent area diameter of the projected area is 〇· The density of 1~〇·5μπι is 10000/mm2 or more. (3) If the quick-cutting steel with excellent manufacturability (1) or (2) is based on mass, it contains: 10 V : 0.05~1.0%;

Nb : 0.005~0.2% ;

Cr : 0.01 ~ 2.0% ;

Mo : 0.05~1.0% ; W : 0.05~1.0% ; 15 Ni : 0.05~2.0% ;

Cu : 0.01 ~ 2.0% ;

Sn : 0.005~2.0% ;

Zn : 0.0005~0.5% ;

Ti : 0.0005~0.1% ; 20 Zr : 0.0005~0.1% ;

Mg : 0.0003~0.005% ;

Te : 0.0003~0.2% ;

Bi: 0.005 to 0.5%; and Pb: 0·005 to 0.5% 10 200840875 One or two or more. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a conceptual diagram showing a straight-cut cutting test method, and Fig. 1(a) is a plan view, and Fig. 1(b) is a plan view. 5 Fig. 2 shows a conceptual diagram of the long-rotation test method and the roughness of the machined surface. The second (a) is a plan view, and the second (b) is a magnified view of the machined surface (infeed mark). Fig. 3 is an optical micrograph showing an example of measurement of MnO of EMPA. Fig. 4 is a photograph showing 10 photographs of sulfides containing MnS as a main component in the present invention, Fig. 4(a) is a photograph of a TEM replica sample, and Fig. 4(b) is an optical micrograph photograph. Fig. 5 is a photograph showing a sulfide of MnS as a main component in a comparative example, a photograph of a TEM replica sample in Fig. 5(a), and an optical microscope photograph in Fig. 5(b). 15 Fig. 6 is a graph showing the change in machinability due to MnO by the roughness of the 800-cut long surface after cutting. Fig. 7 is a view showing the rough chain-hot rolling balance of the machined surface of the invention in the long direction of the invention and the comparative example. Fig. 8 is an explanatory view of a 1/4 depth position of the thickness of the cast piece. [Embodiment] BEST MODE FOR CARRYING OUT THE INVENTION The present invention is a method for improving the machinability by adding B and precipitating BN without adding Pb in a low carbon quick-cut steel which requires more machinability than strength characteristics. Regarding the steel composition, especially by satisfying the appropriate relationship B and N, adding 11 200840875, improving the ductility of the cut-off m and hot rolling, and by lowering the steel

Mn lifting cutting ship and continuous casting when controlling the amount of refractory

7卩 and π became the inventor. Further, the present invention is a method in which a S-type moxibustion product is finely dispersed in a finely dispersible steel. The following rules apply to the stipulations of the ingredients and the reasons for these restrictions. [C] 0.005-0.2% Since the C system is related to the basic strength of the steel and the amount of oxygen in the steel, it will have a great influence on the cutoff m. If the addition of too κ increases the strength, the cutoff m becomes lower, so the upper limit is set to 2%. On the other hand, if it is single, and 屯. Excessive reduction of the amount of c by the human system not only increases the cost, but also causes the deoxidation caused by the mouth c to cause a large amount of oxygen in the steel to remain as a cause of defects such as small holes. Therefore, the lower limit of the amount of C is set to be 0.005% which is easy to prevent a problem such as a small hole. [Si] 0.001 to 0.5% Excessive addition of Si produces hard oxides and reduces machinability, but moderate addition can soften the oxide without deteriorating the machinability. The upper limit is 0.5%, and above this upper limit, a hard oxide is produced. If it is less than 〇 〇〇丨〇 / 〇, the oxide will be difficult to soften and the industrial cost will increase. [Μη]0.3~3.0% Μη is required to fix and disperse the sulfur in the steel to]vinS. Further, in order to soften the oxide in the steel and detoxify the oxide, Μη is also a necessity. The effect is related to the amount of S added. When the amount is less than 0.3%, the addition S cannot be sufficiently fixed to MnS, and S becomes FeS and becomes brittle. If the amount of Μη is too large, the hardness of the bottom iron becomes large and the machinability or cold-rolling workability is lowered, so the limit is 3.0% above the upper limit of 200840875. [P] 0.001-0.2% Since P increases the hardness of the bottom iron in steel, not only cold rolling workability, but also hot rolling workability or casting characteristics, it is necessary to make the upper limit 5 0.2/). . On the other hand, P is also an element having a machinability improving effect, so the lower limit is made 0.001%. [S] 0.30 to 0.60% S is bonded to Μη and is present as a sulfide containing MnS as a main component. Although the sulphide containing MnS as a main component can improve the machinability, the extension of 10 sulphide containing MnS as a main component is also one of the causes of the anisotropy at the time of forging. A large sulphide containing MnS as a main component should be avoided, but from the viewpoint of improving machinability, it is preferable to add a large amount. Therefore, it is preferable to finely disperse the sulfide containing MnS as a main component. In order to improve the machinability without adding pb, it is necessary to add 0.30% or more. On the other hand, if the amount of s added is too large, it is not possible to avoid the occurrence of coarse MnS-based sulfides, and it is also possible to cause cracks in the production due to deterioration of casting characteristics and thermal deformation characteristics due to FeS or the like. Therefore, the upper limit is set to 0.60%. [B] 0.0003 to 0.015% B If it is precipitated as BN, it has an effect of improving machinability. In particular, 20 is finely dispersed in a matrix by precipitation with a sulfide containing MnS as a main component, and the effect is more remarkable. These effects are not significant when the content is less than 〇〇〇〇3%, and when the addition amount is more than 0.015%, the refractory reacts violently in the molten steel, and the refractory melt loss is increased during casting. Damage to manufacturing. Therefore, the range is set to 0.0003%~〇. 13 200840875 Since B is easy to form an emulsion, if the dissolved enthalpy in the molten steel is high, it will be consumed as an oxide, which may reduce the amount of machinability. By adding Ca, the dissolved oxygen (free oxygen) can be reduced to some extent, and by adding B, the yield of B which is substantially BN can be improved, and the machinability can be effectively improved. [0] 0.005 to 0.012% When 0 is not present as an oxide alone, it becomes a bubble when it is cooled, and becomes a small pore. Since the generation of hard oxides may also cause deterioration of machinability or fatigue, control is required. In addition, 〇 and B which are added to improve the machinability may be consumed as oxides in the molten steel, and the amount of Mn which becomes MnS and the amount of enthalpy may be reduced to affect the machinability. When the amount of lanthanum is less than 0.005%, a sulfide containing MnS as a type II of Sims as a main component is generated, and machinability is deteriorated. In addition, it is easy to cause a desulfurization reaction in the molten steel, and it is impossible to perform stable S addition. Because of this, the lower limit is set to 0.005%. When the amount of lanthanum is more than 〇·〇ΐ2%, oxides of Μη and Β are likely to be generated in the molten steel, and Μη which becomes substantially MnS and ΒΝ become ΒΝ, which deteriorates machinability and increases the amount of hard oxides to be increased. The amount of plague produced. In addition, since the refractory dissolution loss is also intense, the upper limit is 0.012%. Ca must be added for the control of the crucible. 20 [Ca]0.0001 ~0.0010%

Ca is an oxygen-removing element, and can control the amount of dissolved oxygen (free oxygen) in the steel material, stabilizes the yield of Μ and B which are easy to form oxides, and suppresses the generation of hard oxides. Further, if it is a trace amount, a soft oxide can be produced, and the effect of improving machinability can be obtained. If it is less than 0.0001%, there is no such effect. 14 200840875 If it is larger than 0.0010/〇, since a large amount of soft oxide is generated, it will have irregularities and adhere to the tool blade, so that the roughness of the machined surface becomes extremely poor. Hard oxides are also produced in large quantities, which may deteriorate machinability or hot ductility. (4) 'The specified composition range is 0 to 10.00%. 5 [Al]Alg0 〇1% A1 is deoxygenin, which will produce A1203 or A1N in steel. However, since Al2〇3 is hard negative, it causes wear and tear during cutting. Further, since the formation of Α1Ν reduces the N for forming BN, the machinability is deteriorated. Therefore, it is made such that it does not generate a large amount of 0.01% or less of Α12〇3 or Α1Ν. 10 〔 Ν〕Ν meets Ν-0.0020% and 1·3χΒ-0·0100^Ν$1·3χΒ + 0.0034 Ν combines with Β to produce ΒΝ, which improves machinability. The lanthanide enhances the cutting inclusions and significantly improves the machinability by subtle high-density dispersion. The mass-to-mass ratio is 化学 : 1 〇 · 8 : 14 (=1 : 1.3) stoichiometry, and 15 just happens to combine 6 and ^ to form BN. BN has solubility for steel, and as the temperature of the steel increases, the solubility increases, and the amount of solid solution N increases. In the rolling temperature region (800 to 11 〇〇. When the amount of solid solution is large, it will become the cause of rolling enthalpy, so it must be limited to a certain amount of solid solution amount, and must be added with B The amount is controlled to be added to the amount of steel. Therefore, if the amount of N is more than + 0.0034% with respect to the amount of N (1·3χΒ) which can be combined with B, the occurrence of calcination will become apparent, so the upper limit is set. It is 1·3χβ + 〇·〇〇34 or less. On the other hand, when the amount of ruthenium added is too small, the amount of ruthenium generated is reduced. The amount of 相对 relative to the amount of β is relative to the amount of ν which can be just combined with β (ι· 3χβ) is less than a 0.0100% 'The amount of Bn required to improve the machinability cannot be obtained, so the lower limit of 15200840875 is set to be more than 1·3χΒ-〇._〇%. Also, when the amount of N is less than 〇〇〇2〇% In the case where the absolute amount of N is insufficient, the distance from the diffusion of steel to the presence of B becomes large. Therefore, even if the stoichiometric ratio of N is added, sufficient BN cannot be produced. Therefore, it must be ensured to be 0.0020% or more. In order to balance both manufacturability 5 and machinability, the content of ^^ must satisfy N20.0020% and l.3xB —0.0100 1·3 Β + 〇 _ 〇〇 34. Μ Ο Ο 投影 投影 投影 投影 投影 投影 投影 投影 投影 投影 投影 投影 投影 投影 投影 投影 投影 投影 投影 投影 投影 投影 投影 投影 投影 5 5 投影 5 5 5 5 投影 5 投影 5 5 投影 5 投影 5 5 5 5 投影 5 投影 投影 投影 5 5 投影 投影In the presence of a certain amount of dissolved oxygen (free oxygen) in the steel, Μη〇 is inevitably formed. Μη0 is a low melting point, soft inclusion, which is not as hard inclusions as 八12〇3. When the ΜηΟ is increased, the amount of Μη which becomes MnS is reduced, and the fine dispersion of MnS is hindered, so that the machinability is deteriorated. In addition, an environment in which a large amount of Mn 产生 is generated is generated. At 15 times, the dissolved oxygen (free oxygen) in the molten steel is at a high concentration, so the amount of B oxide is also increased, and the amount of B which is BN is reduced, and the machinability is further deteriorated. Further, it becomes MnS. Μ 减少 , , § § § § § § § § § § § § § § § § § § § § § § § § § § § § § § § § § § § § § § § § § § § § § § § § § § § ,obviously In the cross section at right angles to the rolling direction of the steel material, if the area of the ΜηΟ in the steel having a projected area equivalent diameter of 〇5 μm or more is more than 15% of the area of the 4 Μ η-type impurity, the machinability and manufacturability will be In order to obtain good machinability and manufacturability, the steel ΜηΟ must be less than 15% of the total Μ-type inclusions. 16 200840875 If the projected area equivalent diameter of MnO is 〇5gm or less, the area ratio is extremely small, so The amount of Μη consumed by MnO is only a little bit, so it won’t

The amount of MnS produced has a large impact. Therefore, it is defined as a projection area equivalent diameter of 0·5 μmη or more. 5 Here, the definition of MnO and the method for measuring the area of the present invention will be described. The MnO is usually present in combination with other oxides in addition to MnO alone. In the present invention, MnO is determined by the following method, and the area is determined. 10 The MnO measurement by EpMA is shown in Fig. 3, for example. The dicing is performed at a position which is 1/4 of the diameter of the cross section perpendicular to the rolling direction of the steel material, and the test piece of the embedded resin by the electron probe microanalyzer (ΕΡΜΑ) is subjected to a field of view of 200 μm χ 200 μm. The above measurements. Since Μη013 in the bottom iron 12 of the steel material is present in a state of being contained in the sulfur 15 compound 14 containing MnS as a main component, in the elemental surface analysis by ΕΡΜΑ, the portion where Μη and Ο are overlapped is taken as Μη〇, And find the area. The total Μ-based inclusions are the general term for all the inclusions in the steel and Μη, which are sulfides, Μη〇, and oxides of MnO and other oxides, which are described later as MnS as a main component. For the target. (20) Since all the Μ-based inclusions were fixed by elemental surface analysis and the area was measured, the ratio of the above-described measured MnO area was determined with respect to the area of the total Μ-based inclusion after the measurement. In order to reduce the amount of MnO produced, it can be achieved by reducing the dissolved oxygen (free oxygen) concentration in the molten steel before LF. The dissolved oxygen (free oxygen) concentration should be 17 200840875 200 ppm or less, but if it is excessively reduced, the desulfurization reaction will be carried out between the metal/steel blocks, and it is difficult to ensure the S in the steel to maintain the machinability, so it is necessary to Fully consider it, it should be made l5〇ppm or more. Regarding the dissolved oxygen (free oxygen) control method, it is effective to perform deoxygenation beforehand in the LF treatment. For the control of free 5 oxygen, it is necessary to add Ca, but in addition to this, the addition of si Λ Al, Ti, Zr, Mg, etc. alone or in combination can also achieve an effect. [Dispersion of sulfide with MnS as main component] The projected area equivalent weight of 0·1~0·5μιη is present in a density of 10000/mm2 or more. The sulfide system containing MnS as a main component can improve the machinability of inclusions. The machinability can be significantly improved by fine and high-density dispersion. In particular, when a cutting method called a cutting edge is formed on the machined surface in the case of forming a projection in the longitudinal direction, the presence or absence of the scratch greatly affects the height of the projection, that is, the roughness of the processed surface, but Finely dispersed high-density sulfides with MnS as the main component, so that the steel is homogenized to make the steel have good fracture properties, which can reduce scratches and improve the roughness of the machined surface. It is more effective to increase the roughness of the machined surface of the part that is cut by the equal length of the axis of the 〇A machine. In order to exert the aforementioned effects, it is necessary to have a density of 10,000/mm2 or more, and the aforementioned size must be a projected area equivalent of pinch 01~ 〇·5μηι. The sulfide distribution mainly composed of MnS is observed by an optical microscope 20, and its size and density are measured. Sulfide containing MnS as the main component of the above-mentioned size cannot be confirmed by observation by an optical microscope, and can be observed by a transmission electron microscope (TEM). There is no difference in size and density under the observation of the optical microscope, but the MnS-based sulfide can be recognized by TEM observation, and the present invention controls the control of 18 200840875 by There is a morphological value that achieves the purpose of making a difference from the prior art. In order to make the sulfide containing more than the above-mentioned size of uMnS as a main component at a density of 10,000 pieces/mm2 or more, it is necessary to add a large amount of S exceeding the range of the request item, but a large amount of addition may cause a majority of the coarse 5 MnS as a main component. The probability of sulphide is greatly increased, thereby increasing the rate of enthalpy production during hot rolling. When the amount of the aMnS-based sulfide exceeds the above-mentioned size, the amount of the sulfide containing MnS as a main component may be insufficient to maintain the density required to increase the roughness of the machined surface. Also, less than the minimum diameter Ο. ίμιη does not substantially affect machinability. Therefore, the density of the sulfide containing MnS as a main component in the area of the equivalent area of 影·1 to 〇·5 μη is 10,000 pieces/mm 2 or more. The sulfide having MnS as a main component can be a precipitated core which is difficult to uniformly disperse uniformly in the matrix, whereby the BN can be uniformly dispersed finely, and the BNi machinability, particularly the processed surface roughness, can be made k. The effect of the rise is more significant. 15 In addition, the sulphide with MnS as the main component is not only pure

MnS ' also contains inclusions in which sulfides of Fe, Ca, Ti, Zr, Mg, REM, etc. are co-existing or combined with MnS, or elements other than s such as MnTe form a compound with Μ and solid solution with MnS. Combining the coexisting inclusions or the inclusions precipitated by the oxide as the core, that is, the chemical formula can represent 20 as (Mn, x) (s, Y) (here, sulfide formation other than X: Μη) The inclusion of the element, γ : element other than S and combined with Μη, is generally referred to as the ^11 sulfide-based inclusion. In order to obtain the size and density of the sulfide having MnS as a main component, the ratio Mn/S of Mn and S contained therein is 1.2 to 2.8, which is more effective. 19 200840875 In addition, the solidification cooling rate range can be controlled in order to produce a fine MnS-based sulfide more efficiently. When the cooling rate is less than min, the solidification will be too slow, and the sulfide containing MnS as the main component will be coarsened, and it will be difficult to be finely dispersed. When the cooling rate exceeds 1 〇〇〇C/min, the fineness generated by 5 The density of sulfides containing MnS as a main component is saturated, which increases the hardness of the steel sheet and increases the risk of cracking. Therefore, the cooling rate at the time of casting is preferably 10 to 1 〇〇 ° C / min. In order to obtain the aforementioned cooling rate, it is easy to achieve by controlling the cross-sectional size of the mold, the casting speed, and the like to an appropriate value. This can be applied to both the continuous casting method and the agglomeration method. 10 The term "solidification cooling rate" as used herein refers to the direction of the arrow 15 as shown by the arrow, and the cross-section 17 of each piece 16 of each piece is 1/ of the thicker (L) of the prayer piece. 4 The velocity at the time of cooling from the liquidus temperature to the solidus temperature in the depth position 18 (see Fig. 8(b)). The cooling rate is determined by the following equation from the secondary dendrite arm spacing of the solidified structure in the thickness direction of the slab after solidification. Here, Rc: cooling rate rc/min), λ2: 20 intervals (μιη) of the secondary dendritic arms. That is, since the secondary dendrite arm spacing changes due to the cooling condition, the controlled cooling rate is confirmed by measuring it. Next, the reason for arbitrarily adding the selection element will be described. [Steel strengthening element] 20 200840875 [V] 〇.〇5~ι.〇〇/0 A small amount of H-shaped f carbonitride, which can be strengthened by secondary precipitation hardening. If it contains 1 〇%,; ^/°, the effect of strength can not be achieved, and if the addition amount is greater than ... precipitation of the Taixi stone anti-nitride, it will damage the mechanical properties, so 5 is the upper limit. [Nb] 0.005 to 0.2% = Carbonitride is also formed, and steel can be strengthened by three precipitation hardening.吾 | I I · · · · · · · 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [Cr]〇·〇ΐ~2.0% is an element that enhances hardenability and imparts temper softening resistance. Therefore, the mouth S force = to the strength of the steel. At this time, it is necessary to add 0.01% or more. However, when a large amount is added to the right, Cr carbide is generated and embrittled, so the upper limit is 2.0% 15 . CMo] 0.05^ 1.〇〇/0

The Mo system can temper soften the resistance and enhance the quenching (four) element. If it is less than 0.05%, it will not be effective, but if it exceeds 1%, the effect will be saturated, so it is 0.05%~1.〇〇/. To add a range. 20 [W] 0.05~1·〇〇/0 W can form a money compound. The steel is strengthened by secondary precipitation hardening. If it is less than 0.05 / 〇, there is no effect of strengthening, and if it exceeds 丄〇%, excessive carbon squirrel is precipitated, and the mechanical properties are impaired, so this is the upper limit. [Ni]〇.〇5~2.0% 21 200840875 Νι strengthens the ferrite and iron, improves ductility and improves hardenability, and is also effective for improving corrosion resistance. If it is less than 0. 05%, it has no effect. However, if it exceeds 2.0%, the effect is saturated in terms of mechanical properties, so this is the upper limit. [Cu] 0.01 to 2.0% 5 Cu strengthens ferrite and iron, and is effective for improving hardenability and improving corrosion resistance. If it is less than 0.01%, it has no effect. However, if it is added in an amount of more than 2%, the effect is saturated from the viewpoint of mechanical properties, so this is the upper limit. In particular, the hot ductility is deteriorated and it is likely to be a cause of the pressure delay, so it is preferable to add it simultaneously with Ni. 1〇 [Elements that improve machinability by embrittlement] [Sn] 0.005~2.0%

Sn can embrittle the ferrite and iron to extend the life of the tool and improve the surface roughness. If it is less than 0.005%, it has no effect, and even if it is added more than 2.0%, the effect is saturated, so this is the upper limit. 15 [Zn] 0.0005~0.5%

Zn can embrittle the ferrite and iron to prolong the life of the tool and improve the surface roughness. If it is less than 0.0005%, it has no effect, and even if it is added more than 0.5%, the effect is saturated, so this is the upper limit. [Elements for improving machinability by deoxidation adjustment] 20 [Ti] 0.0005~0.1%

Ti is a deoxidizing element and can control the amount of oxygen in the steel to stabilize the yield of Μ and B which are easy to form an oxide. Moreover, if it is a trace amount, a soft oxide can be produced, and the effect of improving machinability is obtained. If the content is less than 0.0005%, there is no effect at all, and if it is 0.1% or more, a large amount of hard oxide is generated in a large amount. In addition to 22 200840875, Ti which does not form an oxide and solid solution dissolves with N to form a hard TiN. Reduce machinability. Therefore, the specified composition range is 〇 〇〇〇5~〇.丨%.

Ti consumes the N required to form BN because of the formation of TiN. Therefore, the amount of Ding should be less than 0.01%. 5 [ Zr] 0.0005~0.1%

Zr is a deoxidizing element, which can control the amount of oxygen in the steel to stabilize the yield of Μ and B which are easy to form oxides. Moreover, if it is a trace amount, a soft oxide can be produced, and the effect of improving machinability is obtained. If the content is less than 0.0005%, there is no effect at all. When the content is 0.1% or more, a large amount of hard oxide is generated. Therefore, 10 irregularities are generated and adhered to the tool blade. Therefore, not only the surface roughness of the processed surface is extremely deteriorated. Hard shell oxide's reduce machinability. Therefore, the component range is specified to be 0.0005 to 0.1%. [Mg] 0.0003~0.005〇/〇

Mg is a deoxidizing element, which can control the amount of oxygen in the steel, and stabilizes the yield of ^111 and B which are easy to form oxides 15. Moreover, if it is a trace amount, a soft oxide can be produced, and the effect of improving machinability is obtained. If the content is less than 〇·〇〇〇3%, there is no effect at all. When the content is 0.005% or more, a large amount of hard oxide is generated in a large amount. Therefore, unevenness is generated and adheres to the tool knives. Therefore, not only the surface roughness of the processed surface is extremely deteriorated. It also produces a large amount of hard oxides, which reduces the machinability. 20 Therefore, the composition range is specified to be 0.0003 to 0.005%. [Sulphide Morphology Control and Tool - Element for Lubrication between Steels to Improve Machinability] [Te]Te : 0.0003~0.2%

The Te system enhances the machinability element. In addition, MnTe can be produced or coexisted with MnS 23 200840875 to reduce the opening of MnS) At this system can reduce the anisotropy: Second, it has the effect of controlling the shape extension of MnS. Due to the aforementioned effects, if the content is large =, ° does not exhibit a decrease in 5 10 when the content is less than 3%. "Easy to = original: (4) and heat extension [Bi] 0.005 to 〇 5 〇 / 〇 Βι is a halogen that improves the machinability. When it is less than 0.005%, it does not exhibit the above-mentioned '卩& plus more than 0.5%'. The machinability improvement effect will also be saturated, and the hot ductility will be deteriorated. 〕0.005~〇5%

Pb is an element that improves machinability. When it is less than (10)·, the above effect is not exhibited. Even if the addition exceeds 〇·5%, the machinability improvement effect is saturated, and the hot ductility is deteriorated, which is a cause of thief. Example 15 The present invention is explained by way of examples. The effect of the invention examples of Examples 1 to 72 shown in Tables 1 to 4 was that the acupuncture was dissolved in a 27-mesh converter and cast to a solidification cooling rate of 4 to 18 ° C / min. The solidification cooling rate of the steel of the claim 1 and the steel of the claim 6 of 62 to 72 is 1 to 7 ° C / min, and the solidification of the steel of the claims 2 to 6 of the examples 9 to 61 is 20 The steel of the comparative example of Examples 73 to 102 shown in Tables 5 to 6 was melted in a 270 t converter, and then cast to a solidification cooling rate of 4 to 7 ° C / min. In the comparative example, the 27〇t converter material was pressed into steel slabs and then rolled into φ9·5. The cp9.5mm rolled material was drawn to cp8mm as a test material. From the steel embryo and 18 在 before rolling. Mm angle casting material mining 24 200840875 Take tensile test piece as thermal ductility evaluation. In addition, the adjustment of solidification cooling rate is borrowed The size of the mold section or the casting speed is controlled. The machinability of the material is based on the drilling test under the conditions shown in Table 7, the straight cutting test under the conditions shown in Table 8, and the long-direction rotation test under the conditions shown in Table 9. 5 The three cutting methods of the table were evaluated. The drilling test is a method of evaluating the machinability with a cutting speed of up to 1000 mm of cumulative hole depth (so-called VL1000, unit: m/min). The method of evaluating the roughness of the machined surface by the tool of the high speed steel to offset the shape of the tool (constituting the shape of the blade). The outline of the above experimental method is shown in Fig. 1. In the experiment, 1 测定 is measured by a stylus type roughness meter. The roughness of the machined surface when processing 200 grooves, the surface roughness Rz (unit: μιη) of 1〇 is used as an index to show the roughness of the machined surface. The long-direction rotary test system sends the superhard tool 1 in the long direction. Further, in the cutting direction 3, the cutting method of the outer periphery of the steel piece cut into the test piece 2 is the same as the straight-cut cutting, and the surface roughness of the surface roughness is measured by the transfer of the tool shape. Method for evaluation of the line. The outline of the above experimental method is shown in Fig. 2. This method rotates the test piece 2, and feeds the superhard tool 1 along the test piece 2 (0.05 mm/rev) at a predetermined cutting amount. 6 (1 mm) cutting (cutting speed: 80 m/min), and forming a surface roughness measuring surface 2〇8 on the processing surface 7 by forming a projection called the infeed mark 5, due to scratches The presence or absence of the deterioration 9 affects the height of the protrusion, and becomes the roughness of the scratched surface (theoretical roughness + scratch) 1〇. That is, 'will become the rough surface of the machined surface and the thick edge of the good face The degree (theoretical roughness) 11 has a large influence (refer to Fig. 2(b)). If there is no scratch, it will be close to the roughness of the handle, but if scratches occur, the roughness will decrease (deterioration) with 25 200840875. Fine and high-density dispersion of sulfides containing MnS as a main component can reduce the scratches and improve the roughness of the machined surface by homogenizing the steel material. This method can clearly show that MnS is mainly dispersed at a high density. A method of the effect of sulfides. Moreover, since the method can also remarkably indicate the roughness of the machined surface affected by the uneven transfer of the tool due to the wear of the tool after a large amount of cutting, the test can evaluate the machinability after the tool wear is performed. The difference between the 800 post-cut surface roughness was evaluated. The roughness of the machined surface was measured by a stylus type roughness meter, and the 10-point surface roughness Rz (unit··μιη) was used as the index indicating the roughness of the machined surface. Regarding the chip handling property, it is preferable that the radius of the chip curvature is smaller or the cut is better. Even if the number of turns is large, the radius of curvature is small, or the radius of curvature is large, but the chip length is not as long as l〇〇mm, which is good. The chips having a chip size of more than 20 mm and a radius of curvature of 3 or more continuous curls and extending long are defective, and are referred to as X. 15 Regarding the MnO in the steel, the area ratio of the projected area equivalent diameter is 〇·5μηι or more in the cross section perpendicular to the rolling direction of the steel, and the section is drawn at a right angle from the cp8mm wire drawing and the drawing direction. The diameter of the J/4 depth was cut, and the test piece which was ground in the resin and polished was carried out by an electron probe micro analyzer. In the measurement system, the field of view 2 〇〇μηι 20 20 〇μηη was carried out for 20 fields or more. Therefore, the area ratio was determined from the ratio of the MnO area in the inflammatory substance measured by the elemental surface analysis to the area of the total Μ-based inclusion. Since the MnO in the steel material exists in the state of being contained in MnS, the area in which Μ and Ο analyzed by ΕΡΜΑ are overlapped is taken as the area of 1 〇 11 而 to identify MnS. The coincidence of Μη and Ο is performed by image processing. 26 200840875 The MnO measurement example of ΕΡΜΑ is shown in Figure 3. The maximum diameter of the projected area equivalent diameter is 0.5·μμιη, and the minimum diameter Ο. ίμηι size is determined by the density of sulfide with MnS as the main component, which is the diameter of the cross section perpendicular to the direction of rolling and pulling after cp8mm cable drawing. 4 The depth position was taken by a 5-fold replicate sample method and carried out by a transmission electron microscope. The measurement was carried out at a field of view of 10,000 times at a field of view of 80 Å to 2 fields, and converted to a number of sulfides having MnS as a main component corresponding to 1 mm 2 . The hot ductility was evaluated by the value of the fracture rate of the high temperature tensile test at 1000 °C. If the reduction ratio of the section is 50% or more, a good pressure of 10 is allowed. However, if it is less than 80%, the surface is much entangled, and the area of the maintenance treatment after the rolling is required to be large, and it is not suitable for the surface property. Harsh high grade steel. If the reduction ratio of 80% or more is obtained, the surface fatigue can be significantly reduced, and it can be used without maintenance, and can be applied to advanced varieties. In addition, the cost of maintenance can also be reduced. Therefore, the hot ductility of the reduction ratio of 80 〇 / 〇 15 or more is 〇, and the less than 80% is X. The melt loss condition of the plate-shaped refractory for the continuous casting sliding nozzle was evaluated by using MgO C shell (MgO - 87%, Al2 〇 3 = 10%, C = 3%) as the material of the sliding nozzle plate. When the MnO area of 0.55 μm or more is 15% with respect to the total inclusion area, the melt loss ratio of the 20-fired material is set to 1, and the respective melt loss ratios are quantified. When the melt loss ratio is more than 1 ', the refractory melt loss becomes intense. Therefore, the melt loss ratio 丨 is 丨 大于 and is greater than 1 and is evaluated as ><. Inventive Example ～72 Comparative Example With respect to the comparative examples of Examples 73 to 102, the working surface roughness of the drilling tool life, the straight cutting, and the long-direction turning were both good, and the hot ductility was 8 〇 0 /. The above values, 27 200840875, give good manufacturability with lower dissolution ratios. For example, in the invention example of the embodiment, the amount of addition of the B and N balances is controlled to control the smear, and when the amount of Q is controlled by adding Ca and the area ratio of Mn0 is low, the machinability is not deteriorated and high heat is obtained. The value of ductility and the lower loss ratio. Further, in the case of obtaining the b and n balance addition amounts and the lower Mn 〇 area ratio, the good machinability can be obtained. As in Examples 9 to 18 and 56 to 59, when the density of the sulfide as the main component of the fineness satisfies the request 2, the value of the surface roughness of the machined surface, particularly in the long direction, can be further improved. Even in the case of adding any of the selection elements 3 to 6 of the claims 3 to 6 as in Examples 19 to 55 and 60 to 72, good surface roughness and manufacturability were obtained. Among them, Examples 47, 52, 60, and 62 to 67, which are known as the fast-cutting element Pb, are added in a trace amount, and Examples 45, 48, 50, 53, 61, 68, 69 which are also Te of the fast-cutting element are added in a minute amount. Good thermal ductility and machinability can also be obtained by adding 55 and 7 〇 to 72 of Pb and Te. With respect to the above, since the comparative examples are all cast at a small solidification cooling rate, the density of sulfides which are finely composed of MnS as a main component becomes small, and comprehensively exhibits poor machinability, particularly long-distance turning. The roughness of the machined surface is a poor value, and even if it is in the range of the invention of Examples 1 to 8 cast with the same small solidification cooling rate, since the chemical is 20 points, it is not within the scope of the present invention. Shows a poor value. For example, in the comparative example of Example 76, in the case where the area ratio of MnO is high, the roughness of the processed surface becomes a poor value due to the decrease in the amount of the ^^^ and the amount of BN, and the melt loss ratio becomes a large value. . In the comparative example of Example 80, although the area ratio of Mn〇 was 15% or less, the amount of S and Ca was outside the application range, so the hot ductility was a poor value of 28 200840875. As in the comparative example of Example 81, when Ca was not added, the ruthenium could not be controlled, and a large amount of MnO or a hard oxide was generated, so that the hot ductility was less than 80% and the melt loss ratio was a large value, showing poor manufacturability. . Further, Examples 90 and 91 are comparative examples in which the amount of N is outside the lower limit, and the increase in solid solution B increases the hardness and exhibits a value of low hot ductility. Further, in Example 93, in the comparative examples in which the amounts of S and N were outside the upper limit, since the solid solution n was increased, the hot ductility was lowered to exhibit a poor value. Example 102 is a higher ratio of MnO. In comparison, both the surface roughness and the melt loss index show poor values. Fig. 4 is a view showing 10 sheets of a sulfide containing MnS as a main component in the present invention, wherein (a) is a photograph of a TEM replica sample, and (b) is an optical microscope photograph. Fig. 5 is a photograph showing a sulfide of a comparative example using MnS as a main component, (a) is a photograph of a TEM replica sample, and (b) is an optical microscope photograph. In the above-mentioned invention examples and comparative examples, (b) the size and density of sulfides containing MnS as a main component, which are not much different under the observation of an optical microscope, are observed in the TEM 15 replica sample of (a). In the case, a clear difference in size and density is apparent. Fig. 6 shows the machinability change of the MnO area ratio as an example of the roughness of the 800-cut long surface after the cutting. In the case of tool wear during a large amount of cutting, the MnO area ratio > 15% becomes obvious, and the roughness of the machined surface around the uneven transfer by the tool wear is clearly expressed as the boundary 20 here. Fig. 7 is a view showing the roughness-heat extensibility balance of the machined surface of the invention example and the comparative example in the long direction. The processed surface of the invention has a good roughness and a hot ductility of 80% or more. In the comparative example, the roughness of the machined surface and the hot ductility are all in poor areas, or even if the thermal ductility is good, the roughness of the machined surface is not good. 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_l, excitation [M〇'W*SrvZ^Te I銶C encourages PCu.Zn.Mg.a £ i _ CD m 1 ^PCr-Sn-Zr-Te | Xie frequency 6/2^Pli3^J!Ni .Cu.Zn.Mg.Bi | mme-mmi mmm 1 言纲2娜朋1 (XI 1 寿纲2娜朋酿贞6颂朋,励[Pb | mm 1 雾_6^5册(1, tPb.Ni.Cu.Cr Xiayun frequency excitation [Pb.Ni.Cu 识类添咖bM〇1 励[Pb.v.Ni.Cu 云纲6颂朋,励[Pb.W 1 _贞6娜朋働tPtvTl 1 寿 贞 之 » » » » » » » » » » » » » » » » » ire ire ire ire ire ire ire ire ire ire ire ire ire ire ire ire ire ire ire ire ire ire ire ire ire ire ire ire ire ire ire ire ire ire ire ire ire | _颏6颂朋,励[Pb.Te | 言贞6的发»i働tPb-Te.Ni.Cu mmi 1 〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇 〇〇〇〇〇〇雠b rate 〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇0.42 0.55 0.71 0.58 0.88 0.58 0.79 0.34 0.72 0.71 0.71 0.76 0.59 0.34 0.77 0.73 0.65 0.72 0.75 0.88 0.76 0.86 0.86 0.69 0.72 _ raw ammwo) 〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇cn 00 81.3 91.0 rn OO 84.1 5S 80.3 81.2 81.0 81.0 83.0 82.3 80.3 s 53 81.0 80.3 80.9 81.0 53 80.3 80.9 80.9 80.2 Cut 屑 面 〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇 〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇〇 盯 盯 盯 盯驴长方Ο 00 sd inch · CN 卜· § in (N inch · inch · 〇〇3 3 rn 2 oo <5 Ρ $ 对 · 〇 〇 \ S 5 rn p § ρ in S § oo oo 00 rn § rn 00 vd 00 S 00 面面 VL1000 g § § 〇 gt gt § 00 rn § § § S § 2 2 s 〇 \ fN] s Ο rj OO m MnO mm%) oo 10.8 11.0 00 OO £ 00 卜 5 S <N od oo o 5 10.9 00 od 11.3 tN rn ο 00 σ; TEM Guantong MnS density 1025 6941 14015 26099 32619 28000 28627 17246 19864 26425 30012 41021 39569 47551 6764 4166 6702 3001 1575 5745 2925 2762 9125 6196 2762 Calculation result N雠适0.0033~0.0167 0.0072~0.0206 0.0031~0.0165 0.0048~0.0182 0.0020~0.0117 0.0020~0.0154 0.0020~0.0147 0.0020~0.0122 0.0037-0.0171 0.0042~0.0176 0.0027~0.0161 0.0020 ~0.0151 0.0020 ~0.0113 0.0029 ~0.0163 0Ό031 〜 0.0165 0. 0020 〜0.0147 0.0020 〜0.0150 0.0026 〜0.0160 0.0029 〜0.0163 0.0020 〜0.0154 0.0020 〜0.0145 0.0020 〜0.0147 0.0031 〜0.0165 0.0020 〜0.0147 0.0020 〜0.0146 修班mas·%) 0.0120 0.0182 0.0148 0.0170 0.0102 0.0137 0.0128 0.0091 0.0039 0.0045 0.0030 0.0021 0.0041 0.0074 0.0080 0.0070 0.0080 0.0067 0.0071 0.0066 0.0069 0.0070 0.0069 0.0060 0.0064 £0.10 0.09 0.07 0.06 0.07 0.10 0.11 0.06 0.09 0.12 0.06 0.07 S 0.11 0.05 0.06 0.04 Distinguishing 1 mm mm\\ Liu 响 删 称 犹 犹 _ _ _ _ \ \ \ \ \ Deleted and deleted Jianpeng Liu deleted Liu Pengjian deleted mmi Liu Peng i 1 Office Peng 1 Jianpeng Jiandeng paid 2 2 5S $ - inch ε 200840875 fi 1 λ a ίΛ 2 〇 0.00 > | 0.004 1 | 0.003 I | 0.002 I | 0.004 1 0.003 | 0.002 1 | 0.002 1 | 0.003 1 | 0.004 1 0.002 | 0.002 1 | 0.004 1 | 0.003 1 | 0.002 1 1 0.004 1 0.003 | 0.004 1 I o .ooi | 1 0.002 1 1 0.002 1 1 0.003 1 1 0.003 1 | 0.002 1 1 0.001 1 1 0.002 1 1 0.003 1 | 0.002 1 0.003 | 0.003 1 0.002 | 0.0004 1 [0.0005 1 | 0.0051 1 | 0.0019 1 | 0.0005 1 1 0.0016 1 0.0006 | 0.0005 1 | 0.0004 1 1 0.0023 1 1 0.0006 1 1 0.0005 1 1 0.0039 1 | 0.0002 1 1 0.0004 1 1 0.0021 1 1 0.0004 1 | 0.0005 1 0.0004 | 0.0003 1 0.0002 〇 | 0.0073 1 | 0.005 1 | 0.0041 1 | 0.0206 1 0.0176 | 0.0216 1 | 0.0084 1 | 0.0046 1 | 0.0199 1 0.01% | 0.0106 1 | 0.0171 1 | 0.0205 1 | 0.0169 1 1 0.0045 1 0.0090 | 0.0082 1 | 0.0081 | 1 0.0044 1 1 0.0065 1 1 0.0068 1 1 0.0040 1 | 0.0112 1 1 0.0082 1 1 0.0045 1 1 o.oioi 1 | 0.0068 1 0.0069 | 0.0105 1 0.0110 CQ | 0.0056 1 | 0.0182 1 | 0.0075 1 | 0.0091 1 0 .0051 | 0.0112 1 | 0.0061 1 | 0.0091 1 0.0027 I o.oioo | | 0.0103 1 1 0.0158 1 | 0.0082 1 1 0.0064 1 1 0.0071 1 1 0.0068 1 1 0.0011 1 1 0.0050 1 1 0.0131 1 1 0.0134 1 I o. Oioi | 0.0141 | 0.0017 1 0.0059 Ο 0.65 0.40 k42j 0.48 0.62 0.61 0.62 0.63 LM2J 0.49 0.46 0.29 0.22 0.61 0.28 L〇^ I043J 0.45 L242J 0.63 0.10 0.05 0.44 LM1J (4) 0.64 0.39 0.41 〇Η | 0.090 | | 0.071 1 | 0.050 1 | 0.077 1 0.104 | 0.073 | | 0.092 1 | 0.070 1 | 0.072 1 0.088 | 0.091 1 | 0.066 1 | 0.080 1 | 0.064 1 1 0.066 1 0.091 | 0.069 1 1 0.083 1 1 0.062 1 1 0.091 1 1 0.068 1 1 0.080 1 0.050 1 1 0.081 1 1 0.062 1 1 0.071 1 | 0.091 1 0.071 | 0.080 1 0.051 cs UL35| 0.82 [nil 2.71 LL58J 1.88 UL43J 0.99 LL47J 0.84 0.50 LL3?J 1.78 L〇^J UL39J 2.87 3 LL32J LL63J [ml 2 Rn LL32J I 1.59 | | 0.008 1 | 0.007 1 | 0.008 1 | 0.014 1 0.014 | 0.013 1 | o.oio | | 0.008 1 | 0.003 1 0.013 | 0.007 1 | 0.007 1 I o.oii | I o.oio | 1 0.008 1 0.007 | 0.012 1 1 0.012 1 1 0.013 1 1 0.011 1 1 0.014 1 1 0.015 1 | 0.022 1 1 0.005 1 1 0.007 1 1 0.006 1 1 0.013 1 0.009 | 0.012 1 0.017 〇| 0.082 1 | 0.062 1 | 0.075 1 | 0.021 1 0.038 | 0.061 1 | 0.023 1 | 0.040 1 | 0.016 1 0.062 | 0.061 1 | 0.060 1 | 0.041 1 | 0.060 1 1 0.092 1 0.065 | 0.021 1 1 0.042 1 1 0.063 1 1 0.038 1 1 0.054 1 1 0.087 1 | 0.131 1 1 0.046 1 1 0.067 1 1 0.112 1 1 0.034 1 0.055 I o.oii | 0.017 Distinguishing between 11 rewards 1 11 rewards 1 11 rewards 1 11 Scaring J1 t rewards 11 sunny 丨 J1 11 rewards 1 11 rewards 1 丨 earning side 1 t rewards 11 rewards 1 丨 dirty case 1 11 rewards 1 11 瞧 1 11 rewards 1 11晴丨 J1 11瞧1 11 reward 1 丨 earning example 1 丨 earning side 1 11 yeast J1 丨 earning example 1 11 reward 1 11 reward 1 丨 t reward 1 丨 t reward 1 t reward 丨 t 1 t reward P jn 00 ON S3 s Ϊ3 oo a; 8 § 2 200840875 91¥ I Is book f I |b book f | ta-leg, 0 犹f | fecX 〇±|瑕外' MnW | feca, S.Ohim MnW | Ca, S, ON±I sign f, MnO^f | feiB' S.〇.N book k MnW | 1 _ 1 feck ON book f, MnW I fc, N book k MnW | I 1 (7) teB.Ca, 0 Book k MnW | fcB.Ca, STP cake, 0 upper limit, MnW 1 I Prayer J f [SBCX N book k 0T1W, MnW I | no B, Mn〇H 1 ta, MnO^f 1 S 1 |Ca moving k O.NT1W | In secret 1 Is.N upper limit ^ 1 Is.OTlW, (10) trace, MnW 1 kB. SI^TWK MnO^f II 1 z In upper limit 〇τ® outside I 1 \unm 1 Iktp trace 's book f | MnO^f I | MnC^f Μ ί I , student IIXXXXXXXXXXXXXXXXXXX XXXXXXXXXXX 〇〇〇 XXXX o XXXXXXXXXX 〇〇〇XXX 〇〇〇〇 XX 0.61 | 0.65 | 0.28 | 1____I 1__235__1 1__LZ§__1 1__L2?I 0.44 | o 2.00 I 1L85_I | 2.03 | 1__2^31 1__L99__I m (N 1ι^4I 1_L58 I 1__L25__I | 0.29 I 1 0.50 1 1 0.40 1 1__L48__I 1L??I | 1.33 I | 0.48 1__〇^2__I 1_ _〇^4_I 1___I 1L35I 1 1-28 1 Faceted 酔/〇) XXXXXXXXXXXXXXXXXXXXX 〇〇XXXXXXX 50.3 | I__5Z^__I 1__6L〇__1 1__5^5__I 66.8 | 1__5〇j__1 1__54J__1 | 60.1 1 1723I 1__5L2__I 1____I m (N 1__65 , 9__1 i | 52.0 | m cK 1 69.0 1 1__613__I 1__616__I 1___60^__I 1____1 | 82.0 I 1__§23__I 1__623__I 1__52J__1 1__6L?__I 1__59^__I 1___5^2__I | 70.9 1 1 65.6 | Chip surface properties 〇〇〇X 〇〇X 〇〇〇 〇〇〇XX 〇〇〇〇〇XXI Force anal surface roughness I rectangular o 1__10.4 1 m rn 1__13.9 1 1__12,9__I On rn OO rn 1____1 1__^__1 1__m__1 1__m__1 1__1 1 18.0 1 1__iiz__1 〇00 m σ; ON 丨23.1 __I 1__216__I 1__13.2 1 (N cS 1__192__I 1 18.2 | Surface preparation 〇J 〇< iN 00 〇s DC 5 r4 m OO cK 1__1L9__I 1____1 (N 2· 1 12, 1 Η 1____1 00 1_1 ^0__1 cn 1_1 1_167__I r4 OO o <N OO | 10·6 1_1L6__1 1 12.0 1 论 page on VL1000 On 3 5 On 〇〇§ 茬Ξ OO o OO ON 彐S 8 (Ν CN OO 2 彐rn s fN s MnO C®»(%) II I I4.l I 2 1 237 | 1 29.6 I 1 24.6 1 丨· 1 00 CN 1 25.1 I 20.0 1 | 30.6 1 33.8 1 1 29.3 1 丨16.4 j 1 24.3 j 1 21.8 1 15.8 | cS 丨i 丨25.3 1 CN OO OO m cK 1 17.6 1 1 16.7 | TEM fiber followed by MnS density 4098 | I__3521__1 1102 I 3265 | 1998 | (N 3699 | VO in 1 1309 1 卜 | 2009 1 | 3102 1 1006 I <N | 2974 | 1_m__1 Os | 1210 Divination I Lessons I Ν·午纲 0.0020~0.0107 | 0.0137-0.0271 | 0.0020 〜0.0132 | 0.0020 〜0.0152 | 0.0020 〜 0.0100 1 0.0046 ~0.0180 1 0.0020-0.0034 | 0.0020~0Ό113 | 0.0020 ~0.0152 1 0.0020-0.0069 | 0._ ~0.0164 1 〇·_~〇·_ | 0.0020~0.0034 1 0.0034 ~0.0168 | 1 0.0105 ~0.0239 | 0.0020-0.0034 I | 0.0020~0.0034 | | 0.0020 ~0.0141 I | 0.0020-0.0117 1 0.0020-0.0126 1 | ο·ο〇2〇~o.om | 1 0.0020-0.0048 1 | 0.0020 ~0.0034 I | 0.0020~0.0099 | 1 0.0070 ～0.0204 | | 0.0074 〜0.0208 | | 0.0031 〜0.0165 I 1 0Ό083 ～0.0217 | 0.0020 〜0.0056 1 |〇_0020~0.0111 III 0.0077 | | 0.0200 | | 0.0087 | | 0.0118 | 1 0.0091 1 1 0.0207 1 | 0.0018 | 1 0.0019 1 | 0.0169 | | 0.0119 | | 0.0122 I 1 0.0079 1 1 0.0081 1 | 0.0251 | | 0.0018 | | 0.0074 | | 0.0016 I | 0.0019 I 1 0.0140 1 | 0.0291 1 1 0.0045 1 | 0.0019 | 0.0123 | | 0.0254 | | 0.0051 | | 0.0018 | | 0.0012 | 1 0.0045 1 | 0.0039 I £ m Division IL preparation JI 11 round 1 1 to steel 1 1 L Griffin J 1 U_ij 1 1 i:_ij 1 1 t_ij 1 1 t_ij 1 1 t_ij 1 1 t_ij 1 1 _ 1 1 t_ij 1 ratio _ Shu Shu than 1 _ 1 Shu! :_!! 1 丨t_ij 1 丨t_ij 1 丨1 丨t_ij 1 1 t_ij 1 1 t_ij 1 U_ij 1 1 t_ij 1 1 t_ij 1 1 t_u 1 丨 ratio _ 1 1 t_(j 1 11 reward 1 i J- Λ 1 t_j 1 *»'J rn OO OO S3 3 〇〇§§ § ON 8 o § 9ε 200840875 Table 7 Cutting conditions Other cutting speeds of the drill bit 10-200 m/min Feeding 0.25 mm/rev Insoluble cutting oil cp3mm NACHI General drill hole depth 9mm Tool life until breakage Table 8 Cutting condition tool Other cutting speed 8 0m/min Feeding 0.05mm/rev Lubricating water-insoluble cutting oil SKH51 equivalent cutting angle 15° Clearance angle 6° Evaluation point 200 groove 5 Table 9 Cutting condition tool Other cutting speed 80m/min Feeding 0.05mm/rev Cutting 1mm Lubricating water-soluble cutting oil is quite superhard tool P10 kind of cutting angle 10° Clearance angle 7° Evaluation point 800th industry According to the present invention, it is possible to provide a tool having a long life, a machine surface 10 roughness, and a chip handling property at the time of cutting, and it is excellent in the chipping property of the sliding nozzle of the continuous casting. Good rolling ductility Quick-cut steel with excellent performance [Simplified drawing 3) Figure 1 shows the conceptual diagram of the straight-cut cutting test method, Figure 1 (a) shows the top view, and Figure 1 (b) shows the plan. Figure 2 shows The concept diagram of the long-direction rotary test method and the roughness of the machined surface, the second (a) plan view, the second (b) figure is the enlarged view of the machined surface (infeed mark). The third figure shows the MnO of EMPA. Photomicrograph of the measurement example. 37 200840875 Fig. 4 is a photograph showing a sulfide containing MnS as a main component of the present invention, and Fig. 4(a) is a photograph of a TEM replica sample, and Fig. 4(b) is an optical diagram. Fig. 5 is a photograph showing a sulphide containing MnS as a main component in a comparative example, a photograph of a TEM replica sample in Fig. 5(a), and an optical micrograph in Fig. 5(b). The graph shows the change in machinability due to MnO in the longitudinal direction of the 800-cut long surface after cutting. Fig. 7 shows the machined surface of the invention in the long direction of the invention and the comparative example. Figure of the balance of the figure. Fig. 8 is an explanatory diagram of the position of the 1/4 depth of the slab thickness. 】 1···Superhard tool 2···Test piece 3...Cutting direction 4.. Surface roughness measurement surface 5..Infeed mark 6... Cutting amount 7···力口工8 .. . Surface roughness measurement surface 9.. Deterioration due to scratches 10... Roughness of the surface with scratches 11···Roughness of good surface 12...Bottom iron

13...MnO 14...sulphide 15...casting direction 16...casting 17."cross section 18···depth position 38

Claims (1)

200840875 X. Patent application scope: 1. A fast-cut steel with excellent manufacturability, in mass%, containing: C: 0.005~0.2%; Si: 0.001~0.5%; 5 Μη: 0.3~3.0%; Ρ: 0.001 to 0.2%; S: 0.30 to 0.60%; Β: 0.0003 to 0.015%; Ο: 0.005 to 0.012%; 10 Ca: 0.0001 to 0.0010%; and Α1$0·01%, and the N content is N g 0.0020% and Satisfy 1.3xB — 0.0100 g NS 1·3χΒ +0.0034, and the remainder consists of Fe and unavoidable impurities. Also, regarding the MnO in the steel, in the cross section perpendicular to the rolling direction of the steel, the projected area The area of MnO having an equivalent diameter of 0.5 μm or more is 15% or less with respect to the area of the entire Μ-based inclusion. 2. A kind of fast-cut steel with excellent manufacturability, such as the steel of the first application of the patent scope. For the sulfide with MnS as the main component, the projected area equivalent diameter is in the cross section perpendicular to the rolling direction of the steel. The density of 0.1 to 0.15 μm is 20 or more. 3. For the fast-cutting steel with excellent manufacturability as in the first or second patent application, the mass is: V: 0.05~1.0%; Nb: 0.005~0.2%; 39 200840875 Cr: 0.01~2.0%; Mo : 0.05 to 1.0% ; W : 0.05 to 1.0% ; Ni : 0.05 to 2.0 % ; 5 Cu : 0.01 to 2.0 % ; Sn : 0.005 to 2.0 % ; Zn · · 0.0005 to 0.5% ; Ti : 0.0005 to 0.1% Zr: 0.0005 to 0.1%; 10 Mg: 0.0003 to 0.005%; Te: 0.0003 to 0.2%; Bi: 0.005 to 0.5%; and Pb: 0.005 to 0.5% of one or more. 40