CN109628841B

CN109628841B - Corrosion-resistant steel with yield strength of 350MPa for coal transportation open wagon and manufacturing method thereof

Info

Publication number: CN109628841B
Application number: CN201910110919.9A
Authority: CN
Inventors: 郭晓宏; 刘志伟; 张瑞琦; 孙傲; 高磊; 杨玉; 金星; 王洪海; 景鹤; 王鑫
Original assignee: Angang Steel Co Ltd
Current assignee: Angang Steel Co Ltd
Priority date: 2019-02-12
Filing date: 2019-02-12
Publication date: 2020-05-29
Anticipated expiration: 2039-02-12
Also published as: CN109628841A

Abstract

本发明公开屈服强度350MPa级运煤敞车用耐蚀钢及其制造方法。钢中含有C：0.021％～0.054％，Si：0.21％～0.29％，Mn：0.31％～0.44％，P≤0.018％，S≤0.006％，Als：0.015％～0.045％，Cr：0.31％～0.49％，Ni：0.11％～0.19％，Cu：0.21％～0.34％，Ti：0.008％～0.019％，Sb：0.031％～0.079％，Sn：0.021％～0.059％，Mo：0～0.19％，B：0～0.0019％，Ca：0.0008％～0.0030％，余量为铁和不可避免的杂质；135～170mm板坯加热至1228～1249℃，粗轧温度＞1100℃，精轧1000～1100℃开轧，830～895℃结束轧制，卷取温度580～650℃，钢板具有优异的耐硫酸和氯离子腐蚀性能。The invention discloses a corrosion-resistant steel for a coal-carrying gondola with a yield strength of 350 MPa and a manufacturing method thereof. Steel contains C: 0.021%～0.054%, Si: 0.21%～0.29%, Mn: 0.31%～0.44%, P≤0.018%, S≤0.006%, Als: 0.015%～0.045%, Cr: 0.31%～ 0.49%, Ni: 0.11% to 0.19%, Cu: 0.21% to 0.34%, Ti: 0.008% to 0.019%, Sb: 0.031% to 0.079%, Sn: 0.021% to 0.059%, Mo: 0 to 0.19%, B: 0～0.0019%, Ca: 0.0008%～0.0030%, the balance is iron and inevitable impurities; 135～170mm slabs are heated to 1228～1249℃, rough rolling temperature >1100℃, finishing rolling 1000～1100℃ Open rolling, finish rolling at 830-895 °C, and coiling temperature at 580-650 °C, the steel plate has excellent resistance to sulfuric acid and chloride ion corrosion.

Description

Corrosion-resistant steel with yield strength of 350MPa for coal transportation open wagon and manufacturing method thereof

Technical Field

The invention belongs to the field of steel for railway vehicles, and relates to corrosion-resistant steel suitable for being used in a corrosive environment containing an acidic medium and chloride ions and a manufacturing method thereof.

Background

Steel gondola cars are generally only subject to atmospheric corrosion, whereas coal gondola cars are subject to a rather harsh corrosive environment. Firstly, the coal contains sulfide which has stronger chemical corrosion effect on steel; moreover, because water is used for impact during coal mining, the coal contains water, and in addition, certain salts are added to reduce the freezing point in order to prevent freezing during coal transportation in winter, so that chloride ions with extremely high corrosivity are brought.

At present, the coal gondola car is made of aluminum alloy, stainless steel or traditional weathering steel. Although aluminum alloy and stainless steel have good corrosion resistance, the weldability and the formability have certain problems, and the cost is relatively high; the existing weathering steel for the railway freight car has good strength, weldability and formability, but the corrosion resistance of the existing weathering steel cannot meet the requirement; the weather-resistant steel of the new generation of high corrosion-resistant steel is obviously improved in atmospheric corrosion resistance, but is not suitable for a corrosion environment containing an acidic medium and chloride ions.

Chinese patent CN1664152A discloses a high-strength corrosion-resistant steel for railway vehicles and a preparation method thereof, wherein the high-strength corrosion-resistant steel manufactured by the method comprises the following chemical components: less than or equal to 0.10 percent of C, less than or equal to 2.0 percent of Si, less than or equal to 2.0 percent of Mn, less than or equal to 0.040 percent of P, less than or equal to 0.030 percent of S, Cr: 8.0% -12.0%, Ni: 0.2 to 0.5 percent; the invention improves the corrosion resistance of the steel by increasing the content of chromium in the steel. Although the strength of the disclosed steel plate basically reaches 350MPa, the atmospheric corrosion resistance is greatly improved compared with the traditional weathering steel. But the Cr content is 8.0-12.0%, the smelting difficulty is high for a conventional production line, the production is difficult, and the related steel plate is not suitable for a corrosion environment with coexisting sulfuric acid and chloride ions.

Chinese patent CN103074548B discloses a high corrosion resistant high strength Al-containing weathering steel and a manufacturing method thereof, the chemical components of the high corrosion resistant high strength Al-containing weathering steel manufactured by the method are C0.02-0.07%, Si 0.2-1.0%, Mn 0.2-2.2%, P is less than or equal to 0.01%, S is less than or equal to 0.006%, Cu 0.2-0.5%, Cr 0.5-3.5%, Ni 0.2-1.2%, Al 0.4-4.0%, N is less than or equal to 0.005%, one or more of Nb 0.01-0.06%, Ti 0.01-0.10%, V0.02-0.10% are selected and added, and the rest is Fe and inevitable impurities; and Al/Cr is 0.5 to 8.0. The yield strength of the steel plate is 350-500 MPa, the elongation is more than 20%, and the weather resistance is improved by more than one time compared with the performance requirement of the traditional high-strength weather-resistant steel. Although the strength level meets the requirement and the atmospheric corrosion resistance is also improved to a certain extent, the method is not suitable for the corrosion environment with coexisting sulfuric acid and chloride ions.

Chinese patent CN103397280A discloses a corrosion resistant steel and a preparation method thereof, wherein the corrosion resistant steel comprises 0.08-0.12% of C, 0.20-0.40% of Si, 0.36-0.65% of Mn, 0.70-1.10% of Cr, 0.25-0.45% of Cu, 0.08-0.10% of Sb, 0-0.035% of S and 0-0.035% of P. The method comprises the steps of mixing and smelting C, Si, Mn, Cr, Cu, S, P and Fe to obtain molten steel, putting rare earth into the bottom of a ladle, pouring a first volume of the molten steel, adding Sb, pouring a second volume of the molten steel, stirring to obtain a sample, and performing heat treatment to obtain the corrosion-resistant steel. Although excellent corrosion resistance can be obtained in a high-temperature and high-concentration sulfuric acid environment, the corrosion resistance in a corrosion environment in which sulfuric acid and chloride ions coexist is not mentioned, and thus the problems of the prior art cannot be solved.

Chinese patent CN 104294111A discloses a manufacturing method of an aluminum alloy plate for a coal transportation open wagon, and the plate related by the invention is the aluminum alloy plate, so that the cost is high, and the yield strength is only 220-240 MPa.

In the above-mentioned patents, there is no special steel plate suitable for the actual operation environment of the coal gondola car, or the cost is high, or the corrosion resistance, strength and toughness can not meet the use requirements.

Disclosure of Invention

Aiming at the technical problems in the production of steel for the prior open wagon for transporting coal, such as: the aluminum alloy and the stainless steel have high cost and poor welding and formability, and the corrosion resistance of the existing steel can not meet the requirement. The invention aims to provide corrosion-resistant steel with yield strength of 350MPa for a coal transportation open wagon and a manufacturing method thereof, in particular to corrosion-resistant steel with yield strength of 350MPa for the coal transportation open wagon with the thickness specification of 3.0-8.0 mm and the manufacturing method thereof, and aims to solve the problems in the prior art. The steel plate not only has good atmospheric corrosion resistance, but also has excellent corrosion resistance under the coexistence environment of sulfuric acid and chloride ions, and in addition, the steel plate also has high strength, excellent formability and low-temperature toughness, and is suitable for manufacturing coal trucks.

The specific technical scheme is as follows:

the invention provides corrosion-resistant steel for a 350 MPa-grade coal gondola car, which comprises the following chemical components in percentage by mass: c: 0.021% -0.054%, Si: 0.21-0.29%, Mn: 0.31-0.44%, P is less than or equal to 0.018%, S is less than or equal to 0.006%, Als: 0.015% -0.045%, Cr: 0.31% -0.49%, Ni: 0.11-0.19%, Cu: 0.21-0.34%, Ti: 0.008% -0.019%, Sb: 0.031% -0.079%, Sn: 0.021% -0.059%, Mo: 0-0.19%, B: 0-0.0019%, Ca: 0.0008 to 0.0030 percent, and the balance of Fe and inevitable elements.

C: is a main strengthening element in steel, can obviously improve the strength of the steel plate, but the high content of C is unfavorable for the weldability, the toughness and the plasticity of the steel plate. The low C design limits the formation of pearlite structure and other carbides, ensures that the microstructure of the steel is a homogeneous structure, avoids electrochemical corrosion caused by potential difference between heterogeneous phases, and improves the corrosion resistance of the steel, and the C content is controlled to be 0.021-0.054 percent.

Si: si has high solid solubility in steel and good solid solution strengthening effect, and can improve the corrosion resistance of the steel when coexisting with Cu, but the plasticity and the toughness of the steel are reduced and the welding performance is reduced when the content of Si is too high. The invention is mainly used as deoxidizing elements and not used as main strengthening elements, and the content of Si is controlled to be 0.21-0.29 percent.

Mn: the Mn content is controlled to be 0.31-0.44 percent.

P: the atmospheric corrosion resistance of the steel can be effectively improved, but phosphorus is easy to segregate, the cold brittleness of the steel is increased, and the weldability and the formability are not good. In order to ensure the requirements of welding performance and forming performance, the content of P is controlled to be not higher than 0.018 percent.

S: is a harmful element in steel, causes hot brittleness of the steel, reduces the ductility and toughness of the steel, and deteriorates welding performance, and the existence of S deteriorates atmospheric corrosion resistance of the steel, and the content of S is controlled to be not more than 0.006 percent in the invention.

And Als: is a common deoxidizer, 0.015 to 0.045 percent of aluminum is added into steel to refine grains.

Cr, Ni, Cu: the three elements are added into the steel simultaneously, so that the atmospheric corrosion resistance is improved. In the corrosion process of the steel plate, elements such as Cu, Cr, Ni and the like are enriched in the rust layer close to the matrix to form a compact and stable rust layer close to an amorphous state. Meanwhile, Ni can also obviously improve the low-temperature toughness of steel, so that the low-temperature toughness of the base material and a welding heat affected zone is greatly improved. The weight ratio of Ni/Cu is more than 1/2, and the wire-mesh fracture of the Cu-containing steel caused by hot brittleness can be effectively prevented. In the invention, the content of Cr is controlled to be 0.31-0.49%, the content of Ni is controlled to be 0.11-0.19%, and the content of Cu is controlled to be 0.21-0.34%.

Ti: the high-strength nitrogen-fixing element can form a high-temperature stable fine TiN precipitated phase during slab continuous casting, the fine TiN precipitated phase can effectively prevent austenite grains of a continuous casting billet from growing in the heating process, and meanwhile, the high-strength nitrogen-fixing element has an obvious effect of improving the toughness of a heat affected zone during steel welding, and the Ti content is controlled to be 0.008% -0.019%.

Sb and Sn: sb and Sn elements are often continuously enriched in steel as harmful elements, seriously affecting the quality of steel. In the invention, Sb and Sn are effective elements for improving corrosion resistance, and are enriched in a rust layer in a synergistic manner through the compound addition of Sb, Sn and Cr, and a compact oxide film which is higher than a matrix by several times and rich in elements such as Sb, Sn, Cr and the like is formed, so that the transmission of corrosive ions is obviously hindered, and the corrosion environment with coexisting sulfate radicals and chloride ions is more resistant. In order to ensure the desired corrosion resistance, the effect of the three elements must be exerted in common. Meanwhile, Ti and Sb attract each other, and when Ti is deviated to a grain boundary, Sb is dragged to the grain boundary, so that Sb is separated out in the form of fine second-phase particles instead of inclusions, and the particle size is 10-30 nm, so that the strength of the steel plate is improved. Sb is effective in resistance to sulfuric acid and acid corrosion containing chloride, and the higher the Sb amount is, the higher the sulfuric acid resistance is, but the hot workability and toughness of the steel plate and welded joint are lowered. The invention controls the content of Sb to be 0.031-0.079% and the content of Sn to be 0.021-0.059%.

Mo: MoO generation in aqueous solutions₄ ^2-The corrosion resistance of the antifreeze is improved by suppressing the penetration of chloride ions, but the corrosion resistance to sulfuric acid is sometimes deteriorated by containing a large amount of ions, the low-temperature toughness is also deteriorated, martensite is formed during welding, the brittleness of the welded joint is increased, and the effect of suppressing chloride ions is insignificant when a small amount is contained, and the increase in cost is considered. In the invention, the content of Mo is controlled to be not higher than 0.19 percent.

B: when a low-melting-point corrosion-resistant element containing Sb, Cu, and Sn is added, a certain amount of B can suppress deterioration of hot workability. The content range of B is controlled to be not higher than 0.0019 percent.

Ca: the sulfide is spheroidized, the transverse ductility of the steel plate can be further improved, and the cold-bending forming performance is improved. Since the Ca treatment is performed after refining to make the Ca content 0.0008% to spheroidize the sulfides, and the excessive Ca coarsens the sulfides to lower the ductility, the upper limit of the Ca content is limited to 0.0030% and the Ca content is controlled to 0.0008% to 0.0030%.

The invention also provides a manufacturing method of the corrosion-resistant hot-rolled coil plate for the 350 MPa-level coal transportation open wagon, which comprises the steps of slab smelting, continuous casting, heating, rolling, cooling and coiling, and the specific production method comprises the following steps:

(1) smelting and continuous casting process: the method comprises the steps of molten iron pretreatment, converter smelting, top blowing or top-bottom combined blowing, LF furnace desulfurization and calcium treatment to control the form of impurities and improve the ductility, toughness and cold bending performance of steel, and continuous casting adopts electromagnetic stirring and dynamic soft reduction to improve the quality of continuous casting slabs. In the converter process, a mode of adding antimony ingots after tapping is adopted, and argon is used for stirring, so that the alloy is completely melted and the components are uniform. The thickness of the continuous casting billet is 135-170 mm, the continuous casting billet is obviously thinner than the thick continuous casting billet which is mainly applied at present and is 200mm or more, the solidification cooling rate of the continuous casting billet is far greater than that of the traditional thick plate blank, and the secondary dendrite spacing is greatly reduced.

(2) The rolling process comprises the following steps: and heating the continuous casting plate blank to 1228-1249 ℃ by a heating furnace, wherein the heating steel burning atmosphere is a reducing atmosphere, and the air-fuel ratio is lower than 2.0. The high-temperature short-time steel burning technology is adopted, the furnace time of the hot material heating section and the soaking section is not more than 110min, so that the surface defects caused by the precipitation of low-melting-point elements Cu, Sb and Sn on the surface of strip steel are prevented, the small defects generated on the low-melting-point elements Cu, Sb and Sn on the surface of a plate blank can be fully oxidized, loose and easily-removed iron scales are formed, and the surface quality of the strip steel is improved. The rough rolling is carried out in the temperature range higher than 1100 ℃, and the strip steel is not allowed to swing. Finish rolling is started at 1000-1100 ℃, the start rolling temperature of the finish rolling is higher than 1100 ℃, crystal grains of a finished product are not easy to refine, and the fine grain strengthening effect is not good; the temperature of the tail part of the strip steel is reduced quickly below 1000 ℃, so that the load of a finish rolling machine frame is increased, and accidents are easily caused; and finishing rolling at 830-895 ℃, wherein the finishing temperature is regulated to be more than 830 ℃, so that the condition that the rolling mill is overloaded in a two-phase region can be avoided, a deformation temperature region with difficult plate shape control is avoided, and the longitudinal and transverse performance difference of the steel plate can be reduced. However, the finishing temperature is higher than 895 ℃, the grain refinement is insufficient, and the strengthening effect is influenced. The finishing temperature of the invention is preferably controlled to be 864-894 ℃. And after rolling, carrying out laminar cooling and coiling. The coiling temperature is set to be 580-650 ℃ and higher than 650 ℃, fine crystalline structures are not easy to obtain after coiling, and the strength and the toughness are not enough. When the temperature is lower than 580 ℃, excessive bainite transformation occurs, the elongation rate is reduced, and the forming performance is influenced. The coiling temperature of the invention is preferably controlled at 601-649 ℃, and the laminar flow adopts front section centralized cooling.

The corrosion-resistant steel for the coal-transporting gondola car produced by the method has the yield strength of more than 350MPa, the tensile strength of not less than 490MPa, the elongation of not less than 24 percent, the impact toughness of not less than 60J at minus 40 ℃, and qualified cold bending. According to TB/T2375-93, at 45 + -2 deg.C, 70% + -5% RH, 0.01mol/LNaHSO₃The corrosion rate relative to Q345B was less than 55% under the 72h test in solution. According to JB/T7901-1999 at room temperature, 20% H₂SO₄And the corrosion rate of the fully immersed tube in the + 3.5% NaCl solution for 24 hours is less than 4% relative to that of the Q345B.

Has the advantages that:

compared with the prior art, the invention has the following beneficial effects:

(1) a plurality of alloy elements are added simultaneously, particularly the synergistic effect of Cr, Cu, Sb and Sn, and the auxiliary effect of Ti, Mo, B and other elements, and the effects of high strength and corrosion resistance are achieved through the small-amount multi-element effect of the alloy elements.

(2) The thickness of the continuous casting plate blank is 135-170 mm, the short-flow continuous casting and rolling process is adopted, the high-temperature short-time fast burning process is adopted, the efficiency is high, and the energy is saved.

(3) The steel plate not only has good atmospheric corrosion resistance, but also has excellent medium corrosion resistance. Compared with the weather-resistant steel currently used, the corrosion-resistant steel plate for the 350 MPa-grade coal transporting open wagon produced by the invention has the advantages that the atmospheric corrosion resistance is equivalent to that of the weather-resistant steel, but the medium corrosion resistance is obviously improved, particularly the corrosion-resistant steel plate can resist the coexistence of sulfuric acid and chloride ions, the service life of the coal transporting open wagon in severe environment can be prolonged, and the vehicle maintenance cost is greatly reduced.

Detailed Description

The following examples are intended to illustrate the invention in detail, and are intended to be a general description of the invention, and not to limit the invention.

The chemical components of the steel of the invention are shown in table 1, the rolling process of the steel of the invention is shown in table 2, and the mechanical properties of the steel of the invention are shown in table 3. A sample of 50 multiplied by 5mm is cut out from the steel plate of the embodiment 1-10, a periodic infiltration test is carried out according to the test method by referring to the standard TB/T2375-93 periodic infiltration corrosion test method of weather-resistant steel for railways, the test time is 72h, and the results of the atmospheric corrosion resistance of the steel embodiment of the invention are shown in Table 4; a sample of 50X 25X 5mm was cut out from the steel sheets of examples 1 to 10, and the test method was carried out at 20% H according to JB/T7901-1999 "method for testing homogeneous Corrosion Total Corrosion in metallic Material laboratory")₂SO₄+ 3.5% NaCl immersion test for 24H, 20% H resistance for the inventive steel examples₂SO₄The results of the + 3.5% NaCl corrosion test are shown in Table 5.

TABLE 1 chemical composition in wt% of inventive Steel examples

TABLE 2 Rolling Process and mechanical Properties of steels according to examples of the invention

TABLE 3 mechanical Properties of steels of examples of the invention

TABLE 4 test results of atmospheric corrosion resistance of steels according to the examples of the present invention

Steel grade	Relative corrosion rate/%)
		Example 1	53
Example 2	52
		Example 3	55
Example 4	53
		Example 5	54
Example 6	50
		Example 7	51
Example 8	53
		Example 9	54
Example 10	54
		09CuPCrNi-A	52
Q345B	100

Note: plain carbon steel Q345B and high tensile weathering steel 09CuPCrNi-A are comparative samples.

TABLE 5 Steel of the examples of the invention resistant to 20% H₂SO₄+ 3.5% NaCl Corrosion test results

Steel grade	Relative corrosion rate/%)
		Example 1	3.14
Example 2	3.04
		Example 3	2.79
Example 4	3.18
		Example 5	2.48
Example 6	2.85
		Example 7	3.17
Example 8	3.28
		Example 9	2.95
Example 10	3.07
		09CuPCrNi-A	11.1
Q345B	100

As can be seen from tables 1-5, the corrosion-resistant steel for the coal gondola car produced by the technical scheme of the invention has the yield strength of more than 350MPa, the atmospheric corrosion resistance equivalent to that of the existing high-strength weathering steel 09CuPCrNi-A, and SO resistance₄ ^2-+Cl^-The corrosion effect is obviously superior to that of the existing high-strength weathering steel and plain carbon steel Q345B, not only has good atmospheric corrosion resistance, but also has excellent corrosion resistance in the coexistence environment of sulfuric acid and chloride ions, and meanwhile, the steel plate also has high strength, excellent formability and low-temperature toughness, and is suitable for manufacturing coal-transporting open trucks.

Claims

1. A method for manufacturing a corrosion-resistant steel for a 350MPa-grade coal-carrying gondola with a yield strength, wherein the chemical components in the steel are: C: 0.021% to 0.054%, Si: 0.21% to 0.29%, Mn: 0.31%～0.44%, P≤0.018%, S≤0.006%, Als: 0.015%～0.045%, Cr: 0.31%～0.49%, Ni: 0.11%～0.19%, Cu: 0.21%～0.34%, Ti: 0.008%~0.019%, Sb: 0.031%~0.079%, Sn: 0.021%~0.049%, Mo: 0~0.19%, B: 0.00081%~0.0019%, Ca: 0.0008%~0.0030%, the balance is iron and unavoidable impurities;

The production process of steel plate is: slab smelting, continuous casting, heating, rolling, cooling, coiling, among which:

(1) Smelting and continuous casting process: through molten iron pretreatment, converter smelting, LF furnace desulfurization treatment and calcium treatment; continuous casting adopts electromagnetic stirring or dynamic light pressing, and the converter process adopts the method of adding antimony ingots after tapping, using argon gas Stirring; the thickness of the continuous casting billet is 135-170mm;

(2) Rolling process: the continuous casting slab is heated to 1228-1249 ℃ by the heating furnace, the heating and burning atmosphere is a reducing atmosphere, and the air-fuel ratio is lower than 2.0; the heating time of the hot material heating section and soaking section is not more than 110min. ;

The rough rolling temperature is higher than 1101℃, the finishing rolling temperature is 1000～1100℃, and the finishing rolling temperature is 830～895℃. After the rolling is finished, laminar cooling and coiling are carried out, and the coiling temperature is controlled at 601～649 ℃, laminar flow adopts front-end centralized cooling.

2 . The method for producing corrosion-resistant steel for coal-carrying gondolas with a yield strength of 350 MPa according to claim 1 , wherein the thickness of the steel plate is 3.0-8.0 mm. 3 .

3 . The method for producing corrosion-resistant steel for a coal-carrying gondola with a yield strength of 350 MPa according to claim 1 , wherein the finishing rolling temperature is controlled at 864-894° C. 4 .