TW397724B - Casting mild steel strip - Google Patents

Abstract

To continuously cast metal strip, molten metal is introduced into the nip between a pair of parallel casting rolls (16) via a metal delivery nozzle (19) disposed above the nip to create a casting pool of molten metal supported on casting surfaces of the rolls immediately above the nip and the casting rolls are rotated to deliver a solidified metal strip (20) downwardly from the nip. The metal is silicon/manganese killed mild steel having a manganese content of not less than 0.20% and a silicon content of not less than 0.10% by weight and the total aluminum content of the steel is below 0.01% be weight.

Description

Printed by the Consumers' Cooperatives of the Central Bureau of Standards of the Ministry of Economic Affairs A7 B7 V. Invention Description (1)

& MMM The present invention relates to the casting of steel sheets and is particularly useful for the production of soft steel. It has been known to continuously cast metal cymbals in a twin roll casting machine. In this method, the molten metal is introduced into a pair of counter-rotating horizontal casting reels, and the casting rolls are cold moved to solidify the metal shell on the moving reed surface and gather the metal shells together in the rolling part between the rolls. , Production of solidified long products * The products are transported downwards from the rolling section between the two sides. The term "rolled part" is used herein to mean the area where the two rolls are closest to each other. The molten metal can be poured into the small container from the bucket, and the small container flows down through the metal transfer nozzle located above the rolling section, so the molten metal is guided into the rolling section between the two rolls, so that the support is generated in the pressing section. The molten metal casting pool on the regular casting surface above the rolling section extends along the length of the rolling section. The casting pond can be restrained from sliding between the side plates or between the dam and the roller end, thus blocking both ends of the casting pond to prevent sluicing. Twin-roll castings have been used with some success in non-ferrous metals, such as aluminum, that solidify quickly when cooled. However, this technique has problems when applied to cast ferrous metals. A special problem has caused iron-containing gold alloys, which are prone to produce solid inclusions, which block the extremely small metal flow channels required by the dual alloy casting machine. The use of silicon-manganese in the deoxidation of steel barrels has been implemented in the ingot production of the early Bessemer steelmaking process. Therefore, the reaction product, molten manganese silicate, and the residual manganese and silicon in solution in the steel The balance between oxygen and oxygen is well known. However, in the production of steel bars by flat-plate casting and subsequent development of cold rolling technology, the silicon / manganese degassing reaction (except below) is usually avoided, and the use of aluminum all-static steel was considered. In the production of steel bars by flat casting and subsequent hot rolling, often followed by cold rolling, sand / manganese full static steel produces unacceptable—4 a paper size applicable to China National Standard (C.NS) A4 specification (210 x 297 mm ) (Please read the notes on the back before filling out this page) Order A7 B7 printed by the Consumer Cooperatives of the Central Standards Bureau of the Ministry of Economic Affairs 5. Description of the invention (2) High proportion of hairline and other causes caused by the concentration of inclusions in the middle layer of the long product Flaws. The tendency to generate inclusions in a belt or layer by a flat-plate casting method can be reduced by using an aluminum all-static steel. Therefore, it is generally considered that silicon / manganese all-static steel cannot produce copper bars satisfactorily. Therefore, it was previously thought that the continuous casting of steel bars in a two-roller casting machine required the use of aluminum all-static steel. However, in the continuous casting of steel bars, the key point of 蔺 bond 傜 is to produce a finely controlled steel flow at a constant speed along the length of the 锟, and to achieve sufficiently fast and uniform cooling of the steel on the roll casting surface. This requires the molten steel to be restrained, and under the condition that solid inclusions tend to separate out and block the small flow channel, it flows through the minimum flow channel of the refractory material in the metal conveying system. This is a particularly serious problem when casting mild steels with significantly higher melting points and higher viscosities than higher alloy stainless steels, making it almost impossible to cast. After extensive and thorough strip casting research projects of various grades of steel in a continuous strip S casting machine, the inventors determined that aluminum completely static soft copper or a portion of completely static steel with an aluminum residue content of 0.01% or more was generally unsatisfactory. Casting is attributable to the accumulation of solid inclusions and blocking the small flow channels of the metal conveying system, which causes defects and discontinuities in the resulting long product. Unexpectedly, the inventors found that by maintaining the aluminum content below 0.01% by weight and by using silicon / manganese fully-static soft steel with careful selection of the silicon and manganese content ranges, it is easy to produce liquid deoxidation products at the casting temperature. Overcoming these problems. In addition, the inventors discovered that soft-selling long products can be cast without hairline and other common defects of silicon / manganese all-static steel. This is due to the fact that rapid solidification in a two-roller casting machine can avoid large inclusions; and the two-roller casting method causes the inclusions to be evenly distributed throughout the strip rather than concentrated in the middle layer. This paper size applies Chinese National Standard (CNS) A4 (210X297 mm) (please read the precautions on the back before filling out this page) Order-Printed by the Consumer Standards Cooperative of the Central Standards Bureau of the Ministry of Economic Affairs A7 B7 V. Invention Description ( 3)

Richards et al. US Patent No. 3,412,781 shows a method of continuous casting steel plate, in which the steel body composition is adjusted to contain 0.01 to 0.08% Shuo, 0.20 to 0.60% Manganese, 0 * 03 to 0.085 and not more than 0.015% aluminum . It has been found that it is not possible to cast such a combination steel in twin-roll strip casting to produce strips of acceptable quality.

Smith U.S. Patent No. 4,529,441 shows a method for continuous casting of electric furnace copper, in which silicon is added back to the melt in the range of 0.05 to 0.25%, and the melt composition is composed of up to 0.06% sulfur, up to 0.04% sulfur, and up to 0.15% phosphorus. Up to 1.0% and not more than 0.001% silicon. The example of the patent case found that the steel was treated with aluminum in a quiet manner. Special Example 1 uses 0.015% aluminum, Example 2 contains 0.012% aluminum and Example 3 contains 0.020% aluminum. It was found that aluminum with this content was harmful to the continuous strip casting of spades. According to the present invention, a method for continuously casting a certain metal sheet is provided according to the present invention. In the method, molten metal is introduced into a rolling section between a pair of parallel casting rods through a metal conveying nozzle located above the rolling section to generate support. The molten metal casting pool on the cast iron casting surface just above the rolling section, and the casting rotation rotates to convey the solid metal strip downward from the rolling section, where the metal is silicon / manganese fully static soft steel with manganese content not It is less than 0.20% and the silicon content is not less than 0.10% by weight. The ratio of manganese to silicon is in the range of 1.4: 1 to 2.8: 1 weight ratio and the total aluminum content of China Steel is less than 0.01% by weight. The invention also provides a method for continuously casting a certain metal. In this method, molten metal is introduced into a rolling section between a pair of parallel casting rods through a metal conveying nozzle located above the rolling section to generate support in the exact position. The paper size on the rolling section applies the Chinese National Standard (CNS) Α4 specification (210X297 mm) (please read & note on the back before filling this page)

A7 B7 V. Description of the invention (4) The square metal rod casts the molten metal casting pool of soil, and the casting reel is rotated to convey the solid metal strip from the rolling section downward, wherein the metal is silicon / manganese full static steel with The content of sulphur, manganese and sand is in the following range: 0.02-0.15% by weight of sulphur, 0.20-1.0% by weight of manganese, 0.10-0.5% by weight of silicon and the total aluminum content of its steel is less than 0.01% by weight. In order to obtain the best operation for the production of copper bars with a thickness of 1 mm to 4 mm, the preferred sulphur, silicon and silicon contents are within the following range: m 0.05-0.10% weight ratio. Manganese 0.40-0.80% weight ratio silicon 0.1-0 30% weight ratio diagram: > Brief description of the shed wants to explain the present invention more completely, the application of the present invention to continuous inlay steel sheets will be described with reference to the drawings, with the following attached: Figure 1 can be based on The continuous long obstacles to the operation of the present invention. The plan view of the casting machine. The second side is a side plan view of the long casting machine shown in FIG. 1. The third figure is a vertical sectional view taken along line 3-3 of FIG. 1. 4 圔 is the vertical section taken along line 1-4 of Figure 1; Figure 5 is the vertical section taken along line 5-5 of Figure 1; and Figure 6 illustrates the experimental casting using different composition steels Result 0 Too invented ^ Hanging furnace only -7-This paper size applies Chinese National Standard (CNS) A4 specification (210X297 mm) A7 _B7__ V. Description of the invention (5) The casting machine illustrated by example includes the factory floor 12 erected Main frame 11. The frame 11 supports a casting roller cart 13 that moves horizontally between the assembly station 14 and the bookmaking station 15. The cart 13 carries a pair of parallel casting rollers 16. During the casting operation, molten metal is supplied to the casting rollers from the bucket 17 via the funnel 18 and the conveying nozzle 19. The casting roller 16 is water-cooled, so the surface of the roller during the crushing movement of the metal shell is painted, and it is brought together in the intervening rolling part to produce a solid strip product 20 at the exit of the roller. This production line is fed to the standard coiler 21 and moved to the second coiler 22 afterwards. The container 23 is installed on the frame at the Elin casting station, and the molten metal can flow into the container through the flow chute on the funnel 24 minutes, or can be borrowed if there is a serious product molding failure or other serious functional errors during the casting operation. The emergency stop 25 on the side of the funnel exits the container. The roller cart 13B includes a frame 31 mounted on a rail 33 that extends along the main frame 11 by wheels 32. Therefore, the roller cart 13 is mounted on the rail 33 as a whole. The frame 31 carries a pair of roller frames 34. The rollers 16 are rotatably mounted in the frame. The roller frame 34 is installed on the frame 31 through the complementary pieces 35, 36. Therefore, the roller frame moves on the frame under the influence of the hydraulic cylinder units 37, 38 to adjust the rolling section between the casting rollers 16. , And when the cross bar needs to generate a fragile horizontal line (detailed later), the rollers can be separated from each other in a short time. A double-acting hydraulic pressure cylinder and cylinder unit 39, which is connected between the roller frame 40 and the main frame via an induction, can move the entire frame along the rail 33. Therefore, the induced roller frame is located between the main assembly station 14 and the casting station 15 Move between, and vice versa. The prayer roll 16 is relatively rotated by an electric motor mounted on the frame 31 and a transmission via a transmission shaft 41. Roller 16 has a column that stretches longitudinally and its surroundings ~ 8 ~ This paper size applies Chinese National Standard (CNS) A4 specification (210X297 mm) A7 __._ B7 _ ^ _ V. Description of the invention (6) Spaced water-cooled channels are formed The copper wall, the cold water supply in the water cooling channel is supplied by the water supply pipe of the roller transmission 剌 U1 through the end of the roller, and the water supply pipe is connected to the water supply hose 42 via the rotary gland 43. The rollers are typically about 500 mm in diameter and up to 1300 nun. 俥 produce ‘strips’ with a width of 1300 mm. The bucket 17 is entirely of conventional construction and is supported by a high-lift crane by a yoke 45, so it can be adjusted and positioned by a hot metal receiving station. The barrel is fitted with a plug rod 4S, and the wall rod is driven by the servo cylinder, so that the molten metal flows from the barrel through the outlet nozzle 47 and the refractory air inlet 48 into the funnel 18. The funnel 18 also has a conventional structure. Molded into a wide dish made of refractory magnesium oxide (MgO). The side of the funnel receives molten metal from a bucket and is provided with the aforementioned flow chute 24 and an emergency plug 25. The other side of the funnel is provided with a series of metal outlet holes 52 spaced apart longitudinally. The lower part of the funnel carries a mounting bracket 53 for mounting the funnel to the roller frame 31, and is provided with a drill hole to receive the indicator pin 54 on the frame, so that the bucket can be positioned correctly. Printed by the Consumer Cooperative of the Central Bureau of Standards of the Ministry of Economic Affairs. The transfer nozzle 19 is formed into a refractory material such as alumina graphite. The lower sharpness converges inwardly and downwardly, so it penetrates into the rolling section of the two casting rolls. The delivery nozzle is provided with a mounting bracket 50, so it is supported on the roller frame and its lower portion is formed with a side flange 55 protruding outward, which is positioned on the mounting bracket. The nozzle 19 may have a row of longitudinally spaced, roughly vertically extending runners to generate appropriate low-speed discharge metal throughout the rollers, and to convey molten metal into the rolling section between the two rollers without directly hitting the rollers with initial solidification. surface. In addition, the nozzle can have a single continuous slit opening to convey the low-speed molten metal curtain directly into the rolling section of the second roll conveyor and / or can be immersed in -9-This paper size applies to China National Standard (CNS) 8 4 ^ grid (210 X 297 mm) A7 B7 V. Description of the invention (7) Inside the molten metal pool. The molten metal pool is constrained by a pair of side sealing plates 56 between two 4 m. When the roller parking space is at 9 stations, the side sealing plates are maintained. The stepping end 57 of the roller is held. The side sealing plate 56 is a strong refractory material such as boron nitride, which has a fan-shaped side edge 81 to match the curvature of the stepping end 57 of the roller. The side plate can be installed on the plate base 82. The plate base can be driven by a pair The hydraulic oil cylinder αα early element 83 was moved at the casting station and the two side plates were adjusted to the chewing roller step f: rl > m. Therefore, a ± tss seal was formed in the molten metal pool formed on the casting roller during the casting operation. During the casting operation, the barrel plug 4 is driven to cause molten metal to be poured from the barrel into the funnel through the metal conveying nozzle, so that it flows to the casting roller. The clean head of the long product 20 is guided by the guide plate 96 To coiling machine 21 Jaw clamp 0 Baffle table 9 6 Suspended by the main frame pivot shaft 97 and formed on the clean head XUI m 9 The coil can be turned toward the coil by actuating the hydraulic cylinder ett = > early yuan 98 The machine swings 0. The baffle table 96 can hold the upper strip guide lap 99 driven by the piston cylinder αα early element 101, and the strip product 20 can be constrained between a pair of vertical side rollers 102. The coiler rotates after the jaw clamp of the coiler and the coiled product 20 and the baffle table are swung back to their inoperable position. Here, the pure product is suspended from the rack without products (taken directly to the coiler 21). Hang. The obtained steel sheet product 20 can then be sent to the coiler 22 to produce the final line for transportation from the casting machine. 0 In the operation of the aforementioned device, it was found that the aluminum completely static steel was caused by the liquid steel passing through the small holes of the hopper 18 and the conveying nozzle 19. Salt inclusions cause blocking problems and cannot produce satisfactory steel sheet products. This disturbs the uniform flow of the steel flow to the casting pond, and the results • There is a serious flaw in the production of the flail steel reed product or the produced product by the far Μ method. The combination of silicon and bell is a very effective deoxidizer and it has synergies. 10-This paper size is applicable to China National Standard (CNS) A4 (210X 297 mm). Printed by the Consumers' Cooperative of the Central Standards Bureau of the Ministry of Economic Affairs. A7 B7 5 Invention description (8). The inventors have discovered that a silicon / manganese fully-static steel used as an example of this type of copper bar casting machine can produce a steel reed casting machine with an acceptable oxygen content. Operate so that the resulting strips contain finely and uniformly distributed inclusions in the form of manganese silicate, even when the oxygen content is about 100-U0 ppm and the inclusion density is moderately high, which will not have a serious adverse effect on the mechanical properties of the steel sheet . The oxygen concentration of this pure aluminum static steel is unacceptable, which is attributed to the agglomeration of aluminate inclusions, which may cause plane defects in the strip. Silicate inclusions do not form clusters. In short, the casting of steel bars will constrain them to condense into excessive inclusions, which is detrimental to the mechanical properties of the steel sheet. In addition, inclusions do not hang out because the slab product is not completely rolled out. The concentration of silicon and manganese is selected according to the present invention to maintain the deoxidation products in a liquid state during the casting operation, thus eliminating the problem of blockage of restricted holes in the funnel and metal distribution nozzle. The concentrations of sulphur, manganese and silicon selected according to the present invention are those which can maintain the solidification process in the completely-fertile iron (δ) region. Ideally, the selected composition can obtain the maximum temperature difference between the liquid temperature and the solid temperature. It maintains a sufficiently thick porridge layer during the casting process. Due to this, the quality of the obtained casting rod can have a harmful effect on the casting pool that may interfere with the rapid curing process. Not sensitive. However, it must be kept tightly not too close to the Vostian iron plus ferrous iron zone on the equilibrium phase diagram, due to the difficulty in maintaining balance under the extremely fast cooling conditions of the pin casting machine, and care must be taken, Therefore, there will be no accidental solidification in the iron field with fertilized iron. Increasing the silicon content and reducing the carbon content can promote the formation of δ 'fat iron during the curing process, thus reducing the tendency to produce uneven copper bars with so-called "crocodile skin" defects. Such defects are usually due to the difference between the surface of the solidified shell and the cooling stick _ 11-This paper size applies the Chinese National Standard (CNS) A4 specification (210 X 297 mm) (Notes on the back of the cabinet I, please fill out this page)

A7 B7 Consumption cooperation by employees of the Central Bureau of Standards of the Ministry of Economic Affairs. Du V. Invention Description < 9) Local changes in cooling rate caused by contact (and subsequent changes in tritium structure) 0 If the content of tritium is too low, it may appear as U "Fishbone" flaws. This kind of flaw is a periodic thickness change that roughly extends across the width of the steel bar (or an angle with the width of the steel bar). It is believed that due to the concentration of the solidified shells, the concentration of The performance of the porridge section is caused. If the temperature range of the thick porridge layer is too narrow, the interference on the meniscus of the casting pool may have a significant effect on the thickness and viscosity of the thick porridge layer. The strength of the steel sheet subsequently affected the thickness of the steel sheet. The inventor used different grades of steel to illustrate the thorough operation of this type of steel sheet casting machine. It was determined that the steel sheet to be produced with a thickness in the range of about 1 mm to 4 nun 9 Best steel The composition is as follows: m 0. 05-0 .10% weight ratio manganese 0.50-0 .70% weight ratio silicon 0. 20-0 .30% weight ratio — aluminum is less than 0.008% weight ratio. Steel is preferably preheated to Temperature in the range of 1500 ° C to 1600 ° C for casting. Preferably the funnel is preheated to a temperature range of 1000 ° C to 1300 ° C > and the delivery nozzle is also preheated to a preheat range of 1000 ° c to 1300 ° c 〇The 6th example illustrates various experimental casting results using various silicon and manganese-containing soft steels and melting atmospheres. The 9 points in this figure indicate the successful casting of steels that produce good quality steel bars, while the cross indicates consistent problems and steels. Defective steel. Tests indicate that the steel that falls into Zone 6 圔 A will cause strips of steel strips due to poor deoxidation. -12-The paper size of this paper applies the Chinese National Standard (CNS) A4 specification (210X297 mm) Please read the notes on the back before ordering-A7 B7 V. Description of the invention (1〇) Manganese content is greater than 1 The 0% weight ratio steel that falls within the range of zone B will cause casting problems due to the deposition of MnO fume on the cast iron. The silicon content is greater than 0.5% by weight, so the steel falling into the C zone produces a steel sheet with poor forming characteristics. From Figure 6, it can be seen that the positive result band forms a line, and the most suitable manganese to sand ratio is 2: 1 weight ratio. In particular, the positive result bands roughly correspond to the range of 1.4: 1 to 2.8: 1 weight ratio of manganese to silicon ratio, and obviously the ratio is expected to be in this range to avoid casting problems. Please read the notice of t first, then print the page printed by the Consumer Cooperative of the Central Bureau of Standards of the Ministry of Economic Affairs-printed on a ruler-printed on paper

Claims (1)

Printed by the Consumer Cooperative of the Central Standards Bureau of the Ministry of Economic Affairs. 6. Application for a revision of the patent scope of the patent re-examination case with the scope of patent application No. 841 00269. Date of revision: December 87 1. A continuous casting of a soft steel sheet with a thickness of 1mm to 4mm Method comprising feeding molten soft steel through a conveying system with fine flow channels to a molten soft steel casting pool supported on a casting surface of a counter-rotating chill roll with a rolling section between rolls, and quenching And rotating the roll in the opposite direction to pass the soft steel from the molten casting pool through the rolling section, so that the soft steel is sent down from the rolling section in the form of solidified flakes, and is characterized by: maintaining a low aluminum content in the soft steel 0.01% by weight to avoid harmful clogging of fine flow channels, the content of which is lower than the effective amount of substantially statically treating the mild steel, and by the inclusion of at least 0.20% by weight manganese and at least 0.10% by weight silicon The weight ratio of manganese and sand in the static treatment of the soft steel is from 1.4 · 1 to 2.8: 1 respectively, and the total amount of the rubbed sand is sufficient without substantial formation of solid aluminum inclusions. Static processing of the soft steel, soft steel, respectively, which comprises: 〇_〇5 to 0 · 10% by weight of carbon; 0.4 to 0.8 wt% manganese; and • 0.10 to 0.30 wt% silicon. 2. If the method of claim 1 is applied, it is further characterized by preheating the mild steel to 1,500 to 1,600 ° C and preheating the funnel to 1,000 to 1,300 ° C 'and The metal delivery nozzle is preheated to a range of 1,000 to 1,300. 〇 and other steps, these steps combined with the control of the ratio of aluminum, silicon and manganese can be sufficient to reduce the formation of solid inclusions of the soft steel in the funnel and the conveying nozzle to avoid damage to the funnel and the conveying nozzle ' The mild steel flows evenly. -14- This paper size is in accordance with Chinese National Standard (CNS) 8-4 specifications (21〇 > < 297mm) (please fill in the notes on the back before filling this page), 1Τ Printed by the Consumer Cooperative of the Central Standards Bureau of the Ministry of Economic Affairs. 6. Application for a revision of the patent scope of the patent re-examination case with the scope of patent application No. 841 00269. Date of revision: December 87 1. A continuous casting of a soft steel sheet with a thickness of 1mm to 4mm Method comprising feeding molten soft steel through a conveying system with fine flow channels to a molten soft steel casting pool supported on a casting surface of a counter-rotating chill roll with a rolling section between rolls, and quenching And rotating the roll in the opposite direction to pass the soft steel from the molten casting pool through the rolling section, so that the soft steel is sent down from the rolling section in the form of solidified flakes, and is characterized by: maintaining a low aluminum content in the soft steel 0.01% by weight to avoid harmful clogging of fine flow channels, the content of which is lower than the effective amount of substantially statically treating the mild steel, and by the inclusion of at least 0.20% by weight manganese and at least 0.10% by weight silicon The weight ratio of manganese and sand in the static treatment of the soft steel is from 1.4 · 1 to 2.8: 1 respectively, and the total amount of the rubbed sand is sufficient without substantial formation of solid aluminum inclusions. Static processing of the soft steel, soft steel, respectively, which comprises: 〇_〇5 to 0 · 10% by weight of carbon; 0.4 to 0.8 wt% manganese; and • 0.10 to 0.30 wt% silicon. 2. If the method of claim 1 is applied, it is further characterized by preheating the mild steel to 1,500 to 1,600 ° C and preheating the funnel to 1,000 to 1,300 ° C 'and The metal delivery nozzle is preheated to a range of 1,000 to 1,300. 〇 and other steps, these steps combined with the control of the ratio of aluminum, silicon and manganese can be sufficient to reduce the formation of solid inclusions of the soft steel in the funnel and the conveying nozzle to avoid damage to the funnel and the conveying nozzle ' The mild steel flows evenly. -14- This paper size applies to China National Standard (CNS) 8-4 specifications (21〇 > < 297mm) (please fill out the notes on the back before filling this page), 1T staff of the Central Bureau of Standards, Ministry of Economic Affairs Printed by the Consumer Cooperative A8 B8 C8 _____D8 _ VI. Patent Application Range 3_ The method of applying for patent scope item 1 or 2 is further characterized by controlling the composition of the molten soft steel so that it contains: 0.05 to 0.10% by weight Carbon; 0.50 to 0.70% by weight manganese; 0.20 to 0.30% by weight silicon; and less than 0.008% by weight aluminum. 4. A method of continuously casting a completely static soft steel sheet with a thickness of 1 dirty 1 to 4 nun, by passing a soft steel that has been statically treated by at least one of its included static additives through a conveying system, The molten soft steel casting pool is supported on the casting surface of a counter-rotating chill roll with a rolling section between a pair of rolls. The conveying system includes at least one material leakage and a conveying nozzle, and has a sufficiently fine area to allow the In the flow path of clusters of solid inclusions in aluminum all-steel steel, by rotating the roll in the reverse direction, the soft steel self-casting pool is sent out from the rolling part in the form of solid strips through the roll to form a steel strip. It is characterized by: by maintaining the aluminum content in the all-quiet soft steel below 0.01% by weight and lowering the effective amount of the soft steel, the effective amount of the soft steel is avoided to prevent the harmful clogging of the fine flow channel, and by containing at least 0.2 in it The soft steel is treated with inclusions containing at least 0.1% by weight manganese and at least 0.10% by weight silicon. The weight ratios of manganese and silicon are 1.4: 1 to 2.8: 1, respectively, and the total amount of manganese and silicon is sufficient to prevent The amount of the fine channel blocked The inclusion bodies, the substantial net static treated mild steel, mild steel and controlling the composition of the melt, are that it comprises: from 0.05 to 0.10 wt% carbon; Meng 0.4 to 0.8 wt%; and 0.10 to 0.30 wt% government. -15 · This paper size is applicable to Chinese National Standard (CNS) A4 specification (210X297 mm) " (Please read the precautions on the back before filling this page) ---- I ......... .... Γ 'I ^ I