WO2019116520A1 - Matériau en acier - Google Patents

Matériau en acier Download PDF

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Publication number
WO2019116520A1
WO2019116520A1 PCT/JP2017/044984 JP2017044984W WO2019116520A1 WO 2019116520 A1 WO2019116520 A1 WO 2019116520A1 JP 2017044984 W JP2017044984 W JP 2017044984W WO 2019116520 A1 WO2019116520 A1 WO 2019116520A1
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WIPO (PCT)
Prior art keywords
content
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steel material
steel
corrosion resistance
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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PCT/JP2017/044984
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English (en)
Japanese (ja)
Inventor
清信 菅江
教史 土井
元一 重里
鹿島　和幸
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Nippon Steel Corp
Original Assignee
Nippon Steel and Sumitomo Metal Corp
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Filing date
Publication date
Application filed by Nippon Steel and Sumitomo Metal Corp filed Critical Nippon Steel and Sumitomo Metal Corp
Priority to JP2018515902A priority Critical patent/JP6394839B1/ja
Priority to EP17925535.1A priority patent/EP3524707B1/fr
Priority to PCT/JP2017/044984 priority patent/WO2019116520A1/fr
Priority to AU2017433092A priority patent/AU2017433092B2/en
Priority to KR1020197009199A priority patent/KR102011250B1/ko
Priority to CN201780060066.1A priority patent/CN110168123B/zh
Publication of WO2019116520A1 publication Critical patent/WO2019116520A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/008—Ferrous alloys, e.g. steel alloys containing tin
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur

Definitions

  • the present disclosure relates to steel products.
  • JP-A-2010-064110, JP-A-2012-057236, and JP-A-2012-255184 disclose that each of Sn is 0.005 to 0.3% by mass and 0.02 to 0.40% by mass.
  • JP 2012-144799 A discloses a steel material for a marine structure which contains 0.03 to 0.5 mass% of Sn and which is composed of a ferrite and a hard second phase.
  • Japanese Patent No. 583 91 51 discloses a technique of improving the corrosion resistance of steel by dividing the water cooling into two steps and determining the Sn concentration ratio of the soft structure and the hard structure.
  • JP-A-2010-064110, JP-A-2012-057236, and JP-A-2012-255184 which disclose that corrosion resistance is improved by the addition of Sn, toughness and fatigue characteristics are also disclosed. There is still room for further improvement in corrosion resistance, and there is a need for a technology that satisfies all of corrosion resistance, toughness and fatigue properties.
  • the corrosion resistance of the steel is improved by dividing the water cooling into two steps to determine the Sn concentration ratio between the soft structure and the hard structure, while the low temperature toughness and the fatigue characteristics are further improved. There is room left for
  • An object of the present disclosure is to provide a steel material having excellent corrosion resistance and excellent low temperature toughness and fatigue characteristics.
  • Chemical composition is in mass%, C: 0.01 to 0.20%, Si: 0.01 to 1.00%, Mn: 0.05 to 3.00%, P: 0 to 0.050%, S: 0 to 0.0100%, Sn: 0.05 to 0.25%, Al: 0 to 0.100%, N: 0.0005 to 0.0100%, O: 0.0001 to 0.0100%, Ti: 0 to 0.050%, Nb: 0 to 0.050%, V: 0 to 0.050%, W: 0 to 0.050%, Mo: 0 to 0.050%, Cu: 0 to 0.10%, Ni: 0 to 0.05%, Cr: 0 to 0.10%, Sb: 0 to 0.05%, B: 0 to 0.0010%, Ca: 0 to 0.0100%, Mg: 0 to 0.0100%, REM: 0 to 0.0100%, and the balance: Fe and impurities, Sn ratio represented by [a / b] of Sn concentration [a] of grain boundary and S
  • a numerical range represented using “to” means a range including the numerical values described before and after “to” as the lower limit value and the upper limit value, unless otherwise specified.
  • the steel composition according to this embodiment has a chemical composition in mass%, C: 0.01 to 0.20%, Si: 0.01 to 1.00%, Mn: 0.05 to 3.00%, P : 0 to 0.050%, S: 0 to 0.0100%, Sn: 0.05 to 0.25%, Al: 0 to 0.100%, N: 0.0005 to 0.0100%, O: 0.0001 to 0.0100%, Ti: 0 to 0.050%, Nb: 0 to 0.050%, V: 0 to 0.050%, W: 0 to 0.050%, Mo: 0 to 0 .050%, Cu: 0 to 0.10%, Ni: 0 to 0.05%, Cr: 0 to 0.10%, Sb: 0 to 0.05%, B: 0 to 0.0010%, Ca : 0 to 0.0100%, Mg: 0 to 0.0100%, REM: 0 to 0.0100%, and the remainder: Fe and impurities, with the grain boundary Sn concentration [a]
  • the present inventors prepared various steel plates in which the content of Sn was changed, and investigated the relationship between corrosion resistance and toughness. As a result, it was found that although the corrosion resistance is improved as the Sn content increases, the absorbed energy (low temperature toughness) at 0 ° C. in the Charpy impact test may be deteriorated. For example, when the threshold value of the SAE J2334 test corrosion resistance is 0.6 mm or less and the threshold value of absorbed energy at 0 ° C. is 150 J or more, it was found that it is not easy to stably satisfy both.
  • the inventors of the present invention earnestly obtained the following findings as a result of intensive studies on steel materials excellent in all of corrosion resistance, low temperature toughness and fatigue characteristics.
  • the segregation of Sn in the steel material to grain boundaries is suppressed, and in particular, the Sn ratio represented by [a / b] of the Sn concentration [a] of the grain boundaries and the Sn concentration [b] in the grain. It becomes clear that low temperature toughness and fatigue characteristics are improved while achieving excellent corrosion resistance by making (hereinafter simply referred to as "the Sn ratio between grain boundaries and grain boundaries") not more than 1.2.
  • the means for setting the Sn ratio between the grain boundaries and the inside of the grains to 1.2 or less is not particularly limited.
  • Sn when Sn-containing steel is manufactured under appropriate conditions, Sn It is possible to suppress grain boundary segregation. Specifically, the steel after finish rolling is first slowly cooled, then held at a predetermined temperature for a fixed time to be reheated, and then strongly cooled to a temperature of 550 ° C. or less, thereby grain boundary segregation of Sn. Can be controlled to control the Sn ratio within the above range.
  • C 0.01 to 0.20% C is an element that improves the strength of the steel material. On the other hand, when the C content is excessive, the weldability is significantly reduced. In addition, as the C content increases, the amount of cementite that promotes corrosion as a cathode in a low pH environment increases, and the corrosion resistance of the steel material decreases. Therefore, the C content is made 0.01 to 0.20%.
  • the C content is preferably 0.02% or more, more preferably 0.03% or more.
  • the lower limit of the C content may be 0.05%, 0.07% or 0.09%. Further, the C content is preferably 0.18% or less, more preferably 0.16% or less.
  • the upper limit of the C content may be 0.15% or 0.13%.
  • Si 0.01 to 1.00% Si is an element necessary for deoxidation. In order to obtain a sufficient deoxidizing effect, it is necessary to contain 0.01% or more. On the other hand, when the Si content is excessive, the toughness of the steel material, particularly when welding is performed, the toughness of the base material and the weld heat affected zone is impaired. Therefore, the Si content is made 0.01 to 1.00%.
  • the Si content is preferably 0.03% or more, more preferably 0.05% or more.
  • the lower limit of the Si content may be 0.10%, 0.15% or 0.20%.
  • the Si content is preferably 0.80% or less, more preferably 0.60% or less.
  • the upper limit of the Si content may be 0.50%, 0.40% or 0.30%.
  • Mn 0.05 to 3.00%
  • Mn is an element that has the effect of increasing the strength of steel materials at low cost.
  • the Mn content is set to 0.05 to 3.00%.
  • the Mn content is preferably 0.50% or more, more preferably 0.80% or more.
  • the Mn content is preferably 2.50% or less, more preferably 2.00% or less.
  • P 0 to 0.050%
  • P is an element present as an impurity in the steel material.
  • P is an element that reduces the acid resistance of the steel material, and reduces the corrosion resistance of the steel material in a chloride corrosive environment where the pH of the corrosion interface decreases. P also reduces the weldability and toughness of the steel. Therefore, the P content is limited to 0.050% or less.
  • the P content is preferably 0.040% or less, more preferably 0.030% or less.
  • the upper limit of the P content may be 0.020%, 0.015%, or 0.010% to improve the toughness. Although it is not easy to completely remove P, it is not necessary to exclude this, and the lower limit of P content is 0%.
  • the lower limit of the P content may be 0.0005%, 0.001% or 0.003% because the desulfurization cost for ultra-low phosphorus conversion is high.
  • S is an element present as an impurity in the steel material.
  • S forms MnS in steel materials which is a starting point of corrosion.
  • the S content is preferably 0.0080% or less, more preferably 0.0060% or less, and still more preferably 0.0040% or less.
  • the lower limit of the S content is 0%. Since the refining cost for very low sulfurization is high, the lower limit of S may be 0.0005% or 0.0010%.
  • Sn 0.05 to 0.25%
  • Sn significantly suppresses the anodic dissolution reaction of the steel in a low pH chloride environment, thereby significantly improving the corrosion resistance of the steel in a chloride corrosive environment.
  • the Sn content is made 0.05 to 0.25%.
  • the Sn content is preferably 0.07% or more, more preferably 0.09% or more, and still more preferably 0.10% or more.
  • the Sn content is preferably 0.20% or less, more preferably 0.18% or less, and still more preferably 0.016% or less.
  • Al 0 to 0.100%
  • Al is an element effective for deoxidation of steel materials.
  • Si since Si is contained in the steel material, deoxidation is performed by Si. Therefore, deoxidation treatment with Al is not necessarily required, and the lower limit of the Al content is 0%. However, in addition to Si, deoxidation with Al may be further performed.
  • the Al content exceeds 0.100%, the corrosion resistance of the steel material in a low pH environment is lowered, whereby the corrosion resistance of the steel material in a chloride corrosion environment is lowered.
  • the Al content exceeds 0.100%, the nitride is coarsened to cause a decrease in the toughness of the steel material. Therefore, the Al content is set to 0 to 0.100%.
  • the Al content is preferably 0.005% or more, more preferably 0.010% or more, and still more preferably 0.015% or more, It is more preferable to make it 0.020% or more, and it is particularly preferable to make it 0.025% or more. Further, the Al content is preferably 0.060% or less, more preferably 0.045% or less.
  • N 0.0005 to 0.0100% N turns into ammonia and dissolves, and has an effect of improving the corrosion resistance of a steel sheet in a salt environment by suppressing the pH decrease due to the hydrolysis of Fe 3+ in an environment with a large amount of salt from the air.
  • the N content is made 0.0005 to 0.0100%. Since it is not easy to reduce the lower limit of N more than 0.0005% and the cost becomes high, the lower limit is made 0.0005%. If necessary, 0.0010% or 0.0020% may be the lower limit of the N content. If the content of N exceeds 0.0100%, coarse AlN may be formed to lower the toughness, so the upper limit is 0.0100%. In order to further improve the toughness, 0.0080% or 0.0060% may be the upper limit of the N content.
  • O 0.0001 to 0.0100%
  • O oxygen
  • the O content is preferably 0.0002% or more, more preferably 0.0003% or more.
  • the lower limit of the O content may be 0.0005%, 0.0010%, 0.0015% or 0.0019%.
  • the O content is preferably 0.0090% or less, more preferably 0.0080% or less.
  • the upper limit of the O content may be 0.0060%, 0.0040% or 0.0030%.
  • Ti, Nb, and V are all elements which produce a precipitate and raise the intensity
  • W 0 to 0.050%
  • Mo 0 to 0.050%
  • the contents of W and Mo are each 0.050% or less. It is preferable that any content is 0.040% or less.
  • the upper limit of each of the W content and the Mo content may be 0.030%, 0.020%, 0.010% or 0.005%.
  • the W content and the Mo content be small, and the lower limit of their content is 0%.
  • W and Mo may be contained, and the lower limit of their content may be set to 0.010% or 0.020%.
  • Cu 0 to 0.10%
  • Cu is generally considered to be an element that improves the corrosion resistance of steel materials.
  • the present inventors have found that the corrosion resistance of the steel material is lowered if Cu is contained in a corrosive environment containing chloride as assumed in the present embodiment.
  • the lower the Cu content, the better, and the lower limit of the Cu content is 0%.
  • Cu content is made into 0.10% or less in consideration of the case of mixing as an impurity.
  • the Cu content is preferably 0.07% or less, more preferably 0.05% or less, still more preferably 0.03% or less, and 0.02% or less It is further preferred that The Cu content is particularly preferably 0.01% or less.
  • Ni 0 to 0.05%
  • Ni is considered to improve the corrosion resistance of steel as well as Cu.
  • the present inventors have found that the corrosion resistance of the steel material is lowered if Ni is contained in a corrosive environment containing chloride as assumed in the present embodiment. The lower the Ni content, the better, and the lower limit of the Ni content is 0%. On the other hand, even when it is mixed as an impurity, if the Ni content is 0.05% or less, the decrease in corrosion resistance is small, so the Ni content is made 0.05% or less.
  • the Ni content is preferably 0.03% or less, more preferably 0.02% or less, and still more preferably 0.01% or less.
  • Cr 0 to 0.10% Cr is generally considered to be an element that improves the corrosion resistance of steel materials.
  • the present inventors have found that the corrosion resistance of the steel material is deteriorated if Cr is contained in a corrosive environment containing chloride as assumed in the present embodiment.
  • the lower the Cr content, the better, and the lower limit of the content is 0%.
  • the Cr content is made 0.10% or less in consideration of the case of mixing as an impurity.
  • the Cr content is preferably 0.07% or less, more preferably less than 0.05%, still more preferably 0.03% or less, and 0.02% or less It is further preferred that The Cr content is particularly preferably 0.01% or less.
  • Sb 0 to 0.05% Since Sb is an element that improves the acid resistance, it may be contained as needed.
  • the content of Sb is not essential, and the lower limit of the content is 0%. Incidentally, even if Sb is contained in an amount of more than 0.05%, not only the effect is saturated but also deterioration of the toughness and the like of the steel material is caused. Therefore, the Sb content is made 0.05% or less.
  • the upper limit of the Sb content may be 0.04% or less or 0.03% or less. In order to obtain the above effects, the Sb content is preferably 0.005% or more, more preferably 0.010% or more, and still more preferably 0.015% or more. If it is not necessary to obtain the above effects, the upper limit of the Sb content may be 0.015%, 0.010% or 0.005%, as necessary.
  • B 0 to 0.0010%
  • B is an element that enhances the strength of the steel material by a small amount of addition, and may be contained as necessary.
  • the content of B is not essential, and the lower limit of the content is 0%.
  • the B content is made 0.0010% or less.
  • the B content is preferably 0.0003% or more, and more preferably 0.0005% or more. If it is not necessary to obtain the above effects, the upper limit of the B content may be 0.0005% or 0.0003%, as necessary.
  • Ca 0 to 0.0100% Ca is present in the form of an oxide in the steel material, and has the effect of suppressing the decrease in the pH of the interface in the corrosion reaction part to suppress corrosion, and may be contained as necessary.
  • the content of Ca is not essential, and the lower limit of the content is 0%. In addition, said effect will be saturated when Ca content exceeds 0.0100%. Therefore, the Ca content is 0.0100% or less.
  • the Ca content is preferably 0.0050% or less, more preferably 0.0040% or less. In order to obtain the above effects, the Ca content is preferably 0.0002% or more, and more preferably 0.0005% or more. If it is not necessary to obtain the above effects, the upper limit of the Ca content may be 0.0030%, 0.0005% or 0.0002% or less, as necessary.
  • Mg 0 to 0.0100% Like Ca, Mg has an effect of suppressing the corrosion of the steel material by suppressing the decrease in the pH of the interface in the corrosion reaction part, and therefore may be contained as necessary.
  • the content of Mg is not essential, and the lower limit of the content is 0%. When the Mg content exceeds 0.0100%, the above effect is saturated. Therefore, the Mg content is made 0.0100% or less.
  • the Mg content is preferably 0.0050% or less, more preferably 0.0040% or less. In order to obtain the above effects, the Mg content is preferably 0.0002% or more, more preferably 0.0005% or more. If it is not necessary to obtain the above effects, the upper limit of the Mg content may be set to 0.0030%, 0.0005% or 0.0002% as necessary.
  • REM 0 to 0.0100% Since REM (rare earth element) is an element which improves the weldability of steel materials, it may be contained as needed.
  • the content of REM is not essential, and the lower limit of the content is 0%.
  • the above effect is saturated when the REM content exceeds 0.0100%. Therefore, the REM content is 0.0100% or less.
  • the REM content is preferably 0.0050% or less, more preferably 0.0040% or less.
  • the REM content is preferably 0.0002% or more, more preferably 0.0005% or more. If it is not necessary to obtain the above effects, the upper limit of the Mg content may be set to 0.0030%, 0.0005% or 0.0002% as necessary.
  • REM is a generic term for 17 elements in which Y and Sc are combined with 15 elements of lanthanoid.
  • Y and Sc are combined with 15 elements of lanthanoid.
  • One or more of these 17 elements can be contained in the steel material, and the REM content means the total content of these elements.
  • the balance is Fe and impurities.
  • impurity is a component which is mixed due to various factors such as ore, scrap, etc. and various factors of the manufacturing process when manufacturing steel products industrially, and it is acceptable within a range which does not adversely affect the present embodiment. Means what is done.
  • (B) Sn ratio The ratio of Sn represented by [a / b] of the Sn concentration [a] of the grain boundary and the Sn concentration [b] in the crystal grain: 1.2 or less
  • the crystal grain The Sn ratio between the grain and the grain influences the low temperature toughness, fatigue properties and corrosion resistance of the steel.
  • the Sn ratio between the grain boundary and the inside of the grain is set to 1.2 or less.
  • the Sn ratio is preferably 1.1 or less, more preferably 1.05 or less.
  • the lower limit of the Sn ratio is not particularly required, but the lower limit may be 0.7, 0.8, 0.9 or 1.0.
  • the Sn ratio between the grain boundary and the inside of the grain is determined by the following method.
  • a cylindrical sample having a diameter of 3 mm and a length of 10 mm is prepared from a portion at a position of 1 / 4t of steel material (t represents plate thickness or thickness).
  • the sample is subjected to an impact rupture mechanism in an ultrahigh vacuum attached to an Auger spectrometer (Model 670i manufactured by ULVAC-PHI, Inc.), and the liquid nitrogen temperature (-150 ° C.) at a degree of vacuum (1.0 e -9 torr or less).
  • the fracture surface prepared by breaking in the atmosphere of is observed. Most of the fractures have a river pattern and most of the fractures on the boundary and dimples are observed.
  • the grain boundary and the grain interior of the fractured surface are judged by the macrofractography method, and the Auger spectrum is measured at 10 points each of the grain boundary and the grain.
  • C easy to be segregated to the grain boundaries is analyzed by Auger spectroscopy using a fracture surface determined by the macrofractography method, and the grain boundaries and the inside of the grains are determined.
  • the Sn ratio is calculated by measuring the ratio of the concentration (atomic%) of Sn in the crystal grain boundaries and the crystal grains.
  • the relative sensitivity coefficient is calibrated with Au.
  • the thickness (plate thickness) of the steel plate is preferably 10 to 40 mm.
  • the steel material may be a steel pipe or a shaped steel, and the thickness or thickness thereof may be about 3 to 50 mm.
  • the steel material according to the present embodiment can be manufactured, for example, by using the manufacturing method described below. Preparing a slab having the above-mentioned chemical composition, and heating the slab to 1000 to 1150 ° C .; A rough rolling step of rough rolling the slab; A finish rolling step of subjecting the slab to which rough rolling has been performed to finish rolling so that the finish temperature of the surface is 900 to 750 ° C., while setting the rolling reduction from 950 ° C. to 50% or more; A first accelerated cooling step of acceleratedly cooling the slab (steel material) subjected to finish rolling at a cooling rate of 5 to 10 ° C./s until the surface temperature becomes 630 ° C.
  • Accelerated cooling is interrupted for 30 to 120 seconds for the slab (steel material) after the first accelerated cooling step, and air cooling (hereinafter, accelerated cooling is interrupted and air cooling is referred to as "holding"), and the inside of the slab (steel material)
  • a recuperation step to recuperate the surface temperature to 650-700 ° C. by the heat from the A second accelerated cooling step of accelerated cooling the slab (steel material) after the recuperation step at a cooling rate of 10 to 60 ° C./s until the surface temperature becomes 550 ° C. or lower;
  • An air cooling step of performing air cooling after the second accelerated cooling step It is a manufacturing method of steel materials which have.
  • the heating temperature in the heating step is 1000 to 1150 ° C.
  • the heating temperature in the heating step is 1000 to 1150 ° C.
  • the heating temperature is 1150 ° C. or less, the coarsening of austenite grains is suppressed, and the coarsening of the structure after cooling transformation is also suppressed, so the low temperature toughness is excellent.
  • the heating temperature is 1000 ° C. or more, the alloying elements are sufficiently solutionized, deterioration of the inner quality of the steel is suppressed, and the finishing temperature of rolling is not excessively lowered, so improvement of low temperature toughness Can be expected.
  • the finishing temperature of the surface in the rolling process is 900 ° C. or less, the growth of recrystallized austenite grains is suppressed and the grain refinement is promoted. Further, when the finishing temperature is 750 ° C. or higher, the ferrite structure is less likely to be processed, so the low temperature toughness is improved. Therefore, the finishing temperature is set to 900 to 750.degree. Furthermore, when the rolling reduction from 950 ° C. is 50% or more, partial recrystallization of austenite is difficult to occur, the formation of mixed grain structure is suppressed, and low temperature toughness is improved. Therefore, the rolling reduction from 950 ° C. is 50% or more.
  • water cooling is performed under the following conditions.
  • ⁇ Accelerated cooling (second accelerated cooling process)> Thereafter, it is cooled at a cooling rate of 10 to 60 ° C./s to a temperature of 550 ° C. or less.
  • accelerated cooling under the above conditions, it is possible to suppress grain boundary segregation of Sn and to refine the structure of the steel.
  • the cooling rate is 10 ° C./s or more, the diffusion of Sn is suppressed, and grain boundary segregation is suppressed.
  • the cooling rate is 60 ° C./s or less, the increase in strength of the steel plate is suppressed, and the fatigue resistance is improved.
  • the tensile strength in the range of 400 to 650 MPa.
  • the tensile strength may be 480 to 580 MPa.
  • the grain boundary and the grain interior of the fractured surface were judged by the macrofractography method, and the Auger spectrum was measured at 10 points each of the grain boundary and the grain inside.
  • the fractured surface determined by the macrofractography method was analyzed by Cauger, which easily segregates to the grain boundaries by the Auger spectroscopy spectrum, and the grain boundaries and the inside of the grains were determined.
  • the Sn ratio was calculated by measuring the ratio of the concentration (atomic%) of Sn in the crystal grain boundaries and the crystal grains.
  • the relative sensitivity coefficient was calibrated with Au.
  • ⁇ Corrosion resistance test> From each steel plate, a test piece having a length of 60 mm, a width of 100 mm, and a thickness of 3 mm was cut out and subjected to the SAE J2334 test. In addition, two test pieces were extract
  • the SAE J2334 test is an accelerated deterioration test conducted under the conditions of wet and dry repetitively (wet ⁇ salt adhesion ⁇ dry) as one cycle (total 24 hours), a test simulating a severe corrosive environment where the amount of airborne salt exceeds 1 mdd. It is.
  • the SAE J2334 test was conducted under the following conditions as one cycle.
  • the corrosion pattern under the following conditions is similar to that of the atmospheric exposure test.
  • each test piece was subjected to shot blasting. And about a some test piece, after giving a shot blasting process, the anticorrosion base
  • inorganic zinc rich paint (“Shinto Zink # 2000” manufactured by Shinto Paint Co., Ltd.) and epoxy resin paint (“Neo Gosei # 2300 MC” manufactured by Shinto Paint Co., Ltd.) as mist coat .
  • an epoxy resin paint (“Neo Gosei # 2300 PS” manufactured by Shinto Paint Co., Ltd.) was spray coated to a film thickness of 120 ⁇ m.
  • an intermediate coating an intermediate coating for fluorine resin coating (“SINTAFLON # 100 inner coating” manufactured by Shinto Paint Co., Ltd.) was applied for 30 ⁇ m.
  • a fluorocarbon resin paint (“Sinto Freon # 100" manufactured by Shinto Paint Co., Ltd.) was spray coated to a film thickness of 25 ⁇ m.
  • a cruciform crease was formed on the anticorrosion film to expose a part of the steel material.
  • the amount of corrosion was determined for each of the test pieces that did not form the anticorrosive coating, because a uniform rust layer was formed over the entire surface after the test.
  • the "corrosion amount” was determined as the average reduction in plate thickness of the test piece when the rust layer on the surface was removed. Specifically, the thickness reduction amount was calculated using the weight reduction amount of the test piece before and after the test and the surface area of the test piece, and was used as the corrosion amount.
  • the acceptance criteria in the corrosion resistance test are as follows. An SAE J2334 test was carried out for 120 cycles using a test piece which did not form an anticorrosive film, and one having a corrosion amount of 0.60 mm or less was regarded as a pass. Moreover, 200 cycles of SAE J2334 test were performed using the test piece which has an anticorrosive film, and the thing whose peeling area in a buttocks was 20% or less and whose maximum corrosion depth was 0.40 mm or less was made a pass.
  • the low temperature toughness was evaluated by collecting impact test specimens from the thickness center portion in a direction perpendicular to the rolling direction, and determining absorbed energy (vE 0 ) at 0 ° C. by a V-notch test specimen of JIS Z 2242. The low temperature toughness passed the thing of 150 J or more in absorbed energy.
  • ⁇ Fatigue test> In the fatigue test, the stress amplitude was changed as a test condition, the relationship between the stress amplitude and the fatigue rupture life was represented by an SN diagram, and the fatigue limit was derived.
  • a load ratio (a value obtained by dividing the minimum load by the maximum load) was set to 0.1 using a test piece No. 2 defined in JIS Z 2275.
  • the fatigue rupture life was defined as the point at which the displacement at the maximum load (displacement of the cylinder of the actuator that applies a load to the test body) was increased by 1 mm compared to the start of the test.
  • the fatigue resistance was determined to pass one having a fatigue rupture life of 5.5 ⁇ 10 5 or more.
  • Test No. 1 to 10 are examples of the present disclosure which satisfy all the provisions of the present disclosure.
  • Table 3 in the SAE J2334 test, the amount of corrosion of the unpainted test piece is 0.60 mm or less, the peeled area at the ridge portion of the coated test piece is 20% or less, and the maximum corrosion depth is It was 0.40 mm or less.
  • the toughness test the Charpy absorbed energy at 0 ° C. was 150 J or more. Furthermore, in the fatigue test, the fatigue rupture life was 5.5 ⁇ 10 5 times or more.
  • test No. 1 which is a comparative example. Since 15 and 16 were less than the lower limit to which Sn content in steel materials is prescribed, it resulted in inferior corrosion resistance. In addition, test No. No. 17 exceeded the upper limit specified for the Sn content in the steel material, so the Sn ratio between the grain boundaries and the inside of the grains exceeded 1.2, resulting in poor low temperature toughness and fatigue resistance.
  • test No. 1 which is a comparative example.
  • the content of Mo, Cu, Ni, or Cr in the steel material exceeds the defined upper limit value, resulting in poor corrosion resistance.
  • the steel material according to the present disclosure is suitable for use as a material of large-scale structures such as offshore structures and bridges used in cold regions.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Heat Treatment Of Steel (AREA)

Abstract

L'invention concerne un matériau en acier présentant une composition chimique qui contient, en % en masse, de 0,01 à 0,20 % de C, de 0,01 à 1,00 % de Si, de 0,05 à 3,00 % de Mn, de 0 à 0,050 % de P, de 0 à 0,0100 % de S, de 0,05 à 0,25 % de Sn, de 0 à 0,100 % d'Al, de 0,0005 à 0,0100 % de N, de 0,0001 à 0,0100 % de O, de 0 à 0,050 % de Ti, de 0 à 0,050 % de Nb, de 0 à 0,050 % de V, de 0 à 0,050 % de W, de 0 à 0,050 % de Mo, de 0 à 0,10 % de Cu, de 0 à 0,05 % de Ni, de 0 à 0,10 % de Cr, de 0 à 0,05 % de Sb, de 0 à 0,0010 % de B, de 0 à 0,0100 % de Ca, de 0 à 0,0100 % de Mg et de 0 à 0,0100 % de REM, le reste étant constitué de Fe et d'impuretés. Ce matériau en acier est conçu de sorte que le rapport Sn, qui est exprimé par le rapport a/b entre la concentration en Sn (a) aux limites des grains cristallins et la concentration en Sn (b) dans les grains cristallins, soit inférieur ou égal à 1,2.
PCT/JP2017/044984 2017-12-14 2017-12-14 Matériau en acier Ceased WO2019116520A1 (fr)

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EP17925535.1A EP3524707B1 (fr) 2017-12-14 2017-12-14 Matériau en acier
PCT/JP2017/044984 WO2019116520A1 (fr) 2017-12-14 2017-12-14 Matériau en acier
AU2017433092A AU2017433092B2 (en) 2017-12-14 2017-12-14 Steel Material
KR1020197009199A KR102011250B1 (ko) 2017-12-14 2017-12-14 강재
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CN112391576A (zh) * 2019-08-13 2021-02-23 日本制铁株式会社 低合金耐热钢及钢管
WO2022185632A1 (fr) * 2021-03-03 2022-09-09 Ｊｆｅスチール株式会社 Acier en forme de h
JP2024044876A (ja) * 2022-09-21 2024-04-02 日本製鉄株式会社 バルブプレート及び塗膜付きバルブプレート

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JP7256373B2 (ja) * 2019-03-27 2023-04-12 日本製鉄株式会社 鋼材およびその製造方法
CN110643882A (zh) * 2019-09-12 2020-01-03 宁波天业精密铸造有限公司 一种高性能冲击钢材料及其铸造方法
WO2021095182A1 (fr) * 2019-11-13 2021-05-20 日本製鉄株式会社 Matériau d'acier
CN114599808B (zh) * 2019-11-13 2023-07-21 日本制铁株式会社 钢材
WO2021095183A1 (fr) * 2019-11-13 2021-05-20 日本製鉄株式会社 Matériau en acier
CN111945066A (zh) * 2020-08-04 2020-11-17 浙江晋椿精密工业股份有限公司 一种差速器行星轴用高强度磨光棒
CN111893387A (zh) * 2020-08-04 2020-11-06 浙江晋椿精密工业股份有限公司 一种车窗升降蜗杆用高光洁度磨光棒
CN114058975A (zh) * 2021-11-19 2022-02-18 鞍钢股份有限公司 高热输入焊接的耐低温抗腐蚀货油舱用钢及其制造方法

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CN112391576A (zh) * 2019-08-13 2021-02-23 日本制铁株式会社 低合金耐热钢及钢管
CN112391576B (zh) * 2019-08-13 2022-08-02 日本制铁株式会社 低合金耐热钢及钢管
WO2022185632A1 (fr) * 2021-03-03 2022-09-09 Ｊｆｅスチール株式会社 Acier en forme de h
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JP2024044876A (ja) * 2022-09-21 2024-04-02 日本製鉄株式会社 バルブプレート及び塗膜付きバルブプレート

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EP3524707B1 (fr) 2024-02-07
KR102011250B1 (ko) 2019-08-14
AU2017433092B2 (en) 2020-03-12
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CN110168123B (zh) 2020-08-25
CN110168123A (zh) 2019-08-23

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