Corrosion-resistant steel for sulfuric acid transport tankers and method for manufacturing the same

Abstract

The application discloses a kind of corrosion-resistant steel for sulfuric acid transport tank truck and manufacturing method thereof, the corrosion-resistant steel includes the following weight percentage chemical components: C:0.11~0.13%;Si:0.70~0.90%;Mn:0.70~1.10%;P:≤0.010%;S:0.005~0.015%;Cr:0.60~0.80%;Cu:0.22~0.35%;Alt:≤0.005%;Ti:0.025~0.045%;Mo≤0.20%;Sb:0.11~0.15%, the balance is Fe and inevitable inclusion;The steel plate has the advantages of high strength, high toughness, low yield ratio, high acid resistance and the like, and is mainly used in the field of sulfuric acid transport tank truck.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of corrosion-resistant steel, and particularly relates to a corrosion-resistant steel for a sulfuric acid transport tank car and a manufacturing method thereof. BACKGROUND

[0002] Sulfuric acid is a common industrial raw material and is widely used in industries such as storage batteries, explosives and pigments. It has strong corrosive and oxidizing properties. Its storage and transportation usually use special materials. At present, most sulfuric acid transport tank cars are made of stainless steel, which has high manufacturing cost. The corrosion rates of ordinary acid-resistant steel under different temperature and different concentration of sulfuric acid conditions are significantly different. For example, the corrosion rate of 40-50% concentration sulfuric acid under a service temperature of 50-70℃ is relatively fast, which can reach more than 20 times of the corrosion rate under the condition of 20℃ and 20% sulfuric acid. When the concentration reaches more than 95%, the corrosion rate is significantly reduced, which is less than 1 mm / a under the condition of 40℃.

[0003] If a low-alloy steel plate with relatively low price and excellent sulfuric acid corrosion resistance under multiple temperature and multiple concentration sulfuric acid service conditions can be manufactured for sulfuric acid transport tank cars, it will have better economic efficiency and use value. At the same time, in view of the high-risk characteristics of sulfuric acid transport tank cars, it should also have a higher strength reserve and a low yield ratio. The low yield ratio can delay the fracture under accidental load and improve the safety factor. However, how to design and develop a corrosion-resistant steel with excellent acid resistance and high strength and low yield ratio for sulfuric acid transport tank cars is a technical difficulty.

[0004] Chinese patent CN 115011876A discloses a high-temperature sulfuric acid dew point corrosion-resistant steel and a manufacturing method thereof. The chemical composition of the steel includes C: 0.052-0.087%, Si: 0.21-0.63%, Mn: 0.34-1.04%, P≤0.015%, S:≤0.006%, Cr: 0.43-1.23%, Ni: 0.22-0.43%, Cu: 0.17-0.27%, Sb: 0.06-0.13%, Ti: 0.013%-0.043%, Sn: 0.04-0.11%, Nb: 0.012-0.024%, Alt: 0.024-0.054%, N: 0.008-0.014%, and Ca: 0.0034%-0.0041%. The cast blank is heated at 1183-1203℃, slowly heated below 1081℃, and the heating rate is 8.2-9.2℃ / min; high-temperature fast burning above 1081℃, and the heating rate is 14.2-15.2℃ / min, and the total time in the furnace is 202-212min, and the soaking time is 47-57min. Under the conditions of medium temperature 70℃, sulfuric acid concentration 50%, and full immersion for 24h, the average corrosion rate of the steel is (6.34-7.83) mg / cm 2h. The relative corrosion rate of Q235B is 17.74% to 21.91%, and the average corrosion rate is (13.76-16.81) mg / cm under the conditions of high temperature 130 DEG C, sulfuric acid concentration 80%, and full immersion for 24 hours 2 h. The relative corrosion rate of Q235B is 19.62% to 23.97%, and it can be seen that the corrosion rate is high, and the corrosion level in dilute sulfuric acid is not disclosed, and the composition design is also a low-carbon high-ductility ratio acid-resistant steel. SUMMARY

[0005] To solve the above technical problems, the application provides a kind of corrosion-resistant steel for sulfuric acid transport tank car and a manufacturing method thereof.The steel plate has the advantages of high strength, high toughness, low yield ratio, high acid resistance and the like, and is mainly used in the field of sulfuric acid transport tank car.

[0006] The technical scheme adopted by the application is as follows:

[0007] A kind of corrosion-resistant steel for sulfuric acid transport tank car, the corrosion-resistant steel includes the following weight percentage of chemical components: C: 0.11-0.13%; Si: 0.70-0.90%; Mn: 0.70-1.10%; P: ≤0.010%; S: 0.005-0.015%; Cr: 0.60-0.80%; Cu: 0.22-0.35%; Alt: ≤0.005%; Ti: 0.025-0.045%; Mo ≤0.20%; Sb: 0.11-0.15%, the balance is Fe and unavoidable inclusions.

[0008] The corrosion-resistant steel also contains Ni with a weight percentage of 0.08-0.10%, and the edge crack sensitivity coefficient A=(C+Cu+Sb) / Ni≤7, when A≤7, the edge quality is good.

[0009] Further, the weight percentage of Mo is preferably 0.01-0.20.

[0010] The metallographic structure of the corrosion-resistant steel is ferrite and pearlite structure.

[0011] The R eL of the corrosion-resistant steel is ≥420 MPa, and the R m of the corrosion-resistant steel is ≥600-750 MPa, A≥25%, and the yield ratio is less than 0.75; the relative Q345B corrosion rates in 20 DEG C, 20% H2SO4; 70 DEG C, 50% H2SO4; 40 DEG C, 98% H2SO4 are respectively ≤2%, ≤20%, and ≤80% after immersion for 24 hours.

[0012] The application further provides a manufacturing method of the corrosion-resistant steel for the sulfuric acid transport tank car, which comprises the following steps: obtaining a casting blank through continuous casting, heating, controlled rolling, controlled cooling, coiling and finishing.

[0013] Further, when the casting blank width is 2000-2150mm, the casting blank pulling speed is 0.95-1.00m / min; when the casting blank width is 1500-2000mm, the casting blank pulling speed is 1-1.25m / min; when the casting blank width is 950-1500mm, the casting blank pulling speed is 1.25-1.30m / min; the casting blank is avoided to be hoisted at 600-800℃, and the casting blank straightening temperature is greater than or equal to 850℃.

[0014] In the heating step, when the steel does not contain Ni, the temperature at the end of the first heating section is controlled to be less than or equal to 1040℃, the temperature at the end of the second heating section is controlled to be 1160-1200℃, the sum of the time of the second heating section and the soaking section is controlled to be less than or equal to 110min, and the casting blank discharge temperature is controlled to be 1170-1210℃, and the low-temperature fast burning process is strictly implemented; when the steel contains Ni, the discharge temperature is controlled to be 1190-1230℃.

[0015] In the controlled rolling step, the rough rolling opening rolling temperature is 1020-1080℃; for the hot-rolled plate with a thickness of 3mm≤thickness<8mm, the final rolling temperature is 840-880℃; for the hot-rolled plate with a thickness of 8mm≤thickness<12mm, the final rolling temperature is 820-860℃; for the hot-rolled plate with a thickness of 12mm≤thickness≤16mm, the final rolling temperature is 800-840℃; and the laminar cooling is carried out after rolling.

[0016] If edge cracks occur during rolling, when the edge cracks are less than 8mm away from the edge, the rolling is widened by 5-10mm; when the edge cracks are 8-15mm away from the edge, the rolling is widened by 10-15mm (not including 10mm).

[0017] In the coiling step, for the hot-rolled plate with a thickness of 3mm≤thickness<8mm, the coiling temperature is 600-640℃; for the hot-rolled plate with a thickness of 8mm≤thickness<12mm, the coiling temperature is 570-610℃; for the hot-rolled plate with a thickness of 12mm≤thickness≤16mm, the coiling temperature is 540-580℃.

[0018] In the finishing step, for the steel strip with a thickness of less than or equal to 6mm, the flattening force is 300-400t, and the bending roll force is 25-35KN.

[0019] The components of the corrosion-resistant steel for the sulfuric acid transport tank car provided by the application have the following functions and controls:

[0020] C: one of the main strengthening elements, the low content of C affects the strength of the steel, especially the tensile strength, the higher content of C is beneficial to obtain low yield ratio, but the excessive content of C reduces the plasticity and toughness of the steel plate and the weldability, and also deteriorates the sulfuric acid corrosion resistance of the steel plate. The cylinder of the transport tanker needs to be punched into shape, therefore, based on the good forming property and corrosion resistance, the content of C is controlled to be less than or equal to 0.13%. Meanwhile, based on the safety consideration of low yield ratio, the content of C is preferably 0.11-0.13%.

[0021] Si: the appropriate amount of silicon plays the role of deoxidization and solid solution strengthening to improve the strength, and can be used in combination with Cu and P to improve the sulfuric acid corrosion resistance of the steel. In the present application, a higher content of Si is added to replace Al for deoxidization. In addition, Si forms a thin film of SiO2 in the oxidation atmosphere to improve the sulfuric acid oxidation resistance, especially the acid resistance under the condition of high temperature and high concentration of sulfuric acid. However, the excessive content of Si will produce iron oxide scale strips which are difficult to remove, and such pressure defects are difficult to remove in the shot blasting or electrophoresis process, therefore, the content of Si is controlled in the range of 0.70-0.90% in the present application.

[0022] S: generally, S is a harmful impurity element, easy to form inclusions and segregation defects, thus reducing the plasticity and toughness and being not conducive to processing. However, the higher content of S forms a dense Cu2S passivation film in the high concentration sulfuric acid solution under the cooperation of Cu, which adheres to the surface of the steel plate and hinders the further corrosion in the sulfuric acid environment. Therefore, the content of S is not limited to the ultra-low level in the present application, and the content of S is controlled to be 0.005-0.015%.

[0023] Cr: by inhibiting the reduction reaction of Fe 3+ to Fe 2+ OOH, the generation amount of FeOOH is increased, part of Fe 3+ in α-FeOOH is replaced to form nanoscale oxide α-FexCr(1-x)OOH, so that the rust layer obtains cation selectivity and effectively prevents the further erosion of SO4 2- . Meanwhile, Cr has a certain self-passivation tendency in the steel, which improves the electrode potential of the solid solution. Therefore, a higher content of Cr is adopted to improve the acid resistance, and the content of Cr is controlled to be 0.6-0.8%.

[0024] Ni: the appropriate addition of Ni improves the low temperature toughness of the steel plate, the high content of Ni has good corrosion resistance to acid and alkali, but the effect of Ni on the sulfuric acid corrosion resistance of the low alloy steel is limited, and the cost of Ni is very high, that is, the cost of 10 yuan per ton of steel is increased by 0.01% of Ni per ton of steel. In the present application, the content of Ni is controlled to be less than or equal to 0.10%, and the addition of 0.08-0.10% of Ni can form Cu-Ni high temperature phase to inhibit the occurrence of copper brittleness, or Ni can not be added, but the low temperature fast firing process needs to be adopted to avoid the copper brittleness sensitive temperature zone.

[0025] Cu: On the surface of the steel, a corrosion rust layer rich in oxides is formed, and a thin copper-rich layer is also formed, and a dense thin copper oxide intermediate layer is formed between the corrosion rust layer and the copper-rich layer, thus forming a dense double-layer structure corrosion product layer, effectively isolating the steel matrix from direct contact with the corrosion medium. However, a higher content will cause copper brittleness. Therefore, the Cu content is controlled at 0.22-0.35%.

[0026] Sb: a necessary element for improving acid resistance, forming an Sb2O3 inner film and an Sb2O5 outer film on the surface of the steel during the initial stage of sulfuric acid corrosion. The film has good stability and density, effectively blocking the path of the corrosion medium to the steel matrix. The present application not only resists dilute sulfuric acid corrosion, but also resists 50-98% high concentration concentrated sulfuric acid corrosion. Therefore, the antimony content is designed to be in a relatively high range compared to ordinary acid-resistant corrosion steel, but antimony is a low-melting-point phase (melting point only 630°C), which is easy to liquefy at high temperatures and accumulate at austenite grain boundaries to form cracks, so the Sb content should also not be too high. In summary, the Sb content is controlled at 0.11-0.15%.

[0027] Mo: 1) solid solution strengthening effect on ferrite, improving carbide stability, improving strength, especially hot strength; 2) improving resistance to sulfuric acid at higher service temperatures, preventing pitting tendency. The present application is used for sulfuric acid transport tank cars, so it needs to overcome the high temperature working condition of 100-200°C under sulfuric acid soaking; 3) increase quenching property, the present application has a large thickness span (3-16 mm), in order to ensure the uniformity of F+P type organization in thickness, it is appropriate to add Mo. In summary, Mo is added, but Mo≤0.20%.

[0028] Alt: Al2O3 inclusions are easy to undergo oxidation-reduction reaction with dilute sulfuric acid to generate Al2(SO4)3 and water, further diluting concentrated sulfuric acid, and Al2O3 inclusions in steel become the source of acid corrosion pitting, accelerating corrosion. Therefore, in order to reduce sulfuric acid corrosion, especially to reduce corrosion in a dilute sulfuric acid soaking environment, Al is not used, and Alt≤0.005%.

[0029] Ti: Adding an appropriate amount of Ti can improve the electrode potential of ferrite, which is beneficial to improve acid corrosion resistance, and the bonding force of Ti and C is much greater than that of Cr and C, so Ti is used to eliminate the depletion of Cr at the grain boundary and improve the intergranular corrosion resistance. In the present application, a high content of Cr is added, so an appropriate amount of Ti is also added to eliminate the depletion of Cr. At the same time, Ti is a strong carbonitride forming element, which significantly improves the strength of acid-resistant steel, and when the Ti content is low, it can also inhibit the coarsening of austenite grains in the coarse grain zone. In summary, the Ti content is strictly controlled at 0.025%-0.045%.

[0030] The application provides a manufacturing method of corrosion-resistant steel for sulfuric acid transport tankers, wherein antimony block alloy is added in the LF refining process, and the total weak stirring time before and after feeding calcium wire is greater than or equal to 11 minutes. The steel belongs to a high crack sensitivity steel, and the high temperature plasticity in the range of 600-850 DEG C shows a phenomenon of first increasing and then decreasing. In the low plasticity valley region of 600 DEG C and 800 DEG C, the application avoids hoisting the cast blank in the low plasticity region of 600 DEG C and 800 DEG C. A high straightening temperature greater than or equal to 850 DEG C is used to reduce the crack risk of the cast blank. If edge cracks occur in the rolling process, when the edge crack is less than 8 mm from the edge, the rolling is widened by 5-10 mm; when the edge crack is 8-15 mm from the edge, the rolling is widened by 10 mm to 15 mm.

[0031] The application adopts "controlling S + medium Si + no Al + medium Sb + Mo-Ti micro-alloying", and through the passivation film formed by Cu2S and Sb2O3 and the intergranular corrosion resistance and pitting resistance of Mo-Ti, the sulfuric acid corrosion resistance is excellent, especially the innovative design of "medium Si + no Al" makes the steel have good acid corrosion resistance in both dilute sulfuric acid and concentrated sulfuric acid service conditions. In the aspect of steelmaking and continuous casting, high straightening temperature + drawing speed-width gradient matching is adopted to reduce the edge crack risk of the Sb-Cu type low melting point element corrosion-resistant steel. In the aspect of controlled rolling and controlled cooling, the final rolling / coiling-thickness gradient matching system is adopted to achieve the purpose of excellent performance stability of different thicknesses. In addition, combined with the design of 0.11-0.13% C, a 420 MPa grade high-strength corrosion-resistant steel with low yield ratio for manufacturing sulfuric acid transport tankers is obtained.

[0032] Compared with the prior art, the application has the following beneficial effects:

[0033] The corrosion-resistant steel provided by the application has high strength and low yield ratio, R eL ≥420 MPa, R m ≥600-750 MPa, A≥25%, and the yield ratio is less than 0.75.

[0034] The corrosion-resistant steel provided by the application has high sulfuric acid corrosion resistance: 20 DEG C, 20% H2SO4 immersion for 24 h, the corrosion rate is less than or equal to 0.17 mg / (cm 2 *h), the relative corrosion rate of Q345B is less than or equal to 2%; 70 DEG C, 50% H2SO4 immersion for 24 h, the corrosion rate is less than or equal to 2.8 mg / (cm 2 *h), the relative corrosion rate of Q345B is less than or equal to 20%; 40 DEG C, 98% H2SO4 immersion for 24 h, the corrosion rate is less than or equal to 0.055 mg / (cm 2 *h), and the relative corrosion rate of Q345B is less than or equal to 80%. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 It is a metallographic structure diagram of the corrosion-resistant steel in Example 1.

[0036] Figure 2 The image shows the metallographic structure of the corrosion-resistant steel in Example 3;

[0037] Figure 3 The image shows the surface morphology of the rust layer of the corrosion-resistant steel in Example 1 after immersion in 50% H2SO4 at 70°C for 24 hours. The rust layer contains Cu, S, Sb, etc., which are enriched and form a dense passivation film of Cu2S and Sb2O3, which prevents further corrosion in the sulfuric acid service environment.

[0038] Figure 4 To compare the edge quality of the corrosion-resistant steel in Example 5, a defect similar to "serrated edge" exists;

[0039] Figure 5 The corrosion-resistant steel in Comparative Example 10 was found to have cracks due to the use of inappropriate casting speed and straightening temperature.

[0040] Figure 6 The diagram shows a comparison of the plate shape between Comparative Example 11 and Example 3. Comparative Example 11 shows a clear double wave shape, while Example 3 shows a good plate shape. Detailed Implementation

[0041] This invention provides a corrosion-resistant steel for sulfuric acid transport tank trucks. The main chemical composition and weight percentage (wt%) of the corrosion-resistant steel are as follows: C: 0.11-0.13%; Si: 0.70-0.90%; Mn: 0.70-1.10%; P: ≤0.010%; S: 0.005-0.015%; Cr: 0.60-0.80%; Ni: ≤0.10%; Cu: 0.22-0.35%; Alt: ≤0.005%; Ti: 0.025-0.045%; Mo ≤0.20%; Sb: 0.11-0.15%, with the balance being Fe and unavoidable inclusions.

[0042] When Ni is added, the weight percentage of Ni is 0.08-0.10%, and the edge crack sensitivity coefficient A = (C+Cu+Sb) / Ni ≤ 7.

[0043] The manufacturing method of the corrosion-resistant steel for sulfuric acid transport tank trucks includes the following steps: molten iron pretreatment → converter smelting → LF refining → continuous casting → slab heating → controlled rolling → controlled cooling → coiling → finishing.

[0044] 1) Smelting, refining, and continuous casting processes

[0045] Antimony block alloy is added during the LF refining process, and the total weak stirring time before and after the calcium feeding line is ≥11 min.

[0046] The steel of the present application shows the phenomenon of first increasing and then decreasing in high temperature plasticity in the range of 600-850℃. In the low plasticity valley region of 600-800℃, the present application avoids lifting the casting blank in the low plasticity region of 600-800℃. And the high straightening temperature of >850℃ is used to reduce the risk of casting blank crack. When the casting blank width is 2000-2150mm, the casting blank pulling speed is 0.95-1.00m / min; when the casting blank width is 1500-2000mm, the casting blank pulling speed is 1-1.25m / min; and when the casting blank width is 950-1500mm, the casting blank pulling speed is 1.25-1.30m / min.

[0047] 2) Slab heating, controlled rolling and controlled cooling process

[0048] The present application adopts casting blank landing inspection and cleaning before rolling. In the slab heating process, ① for the case without adding Ni: the temperature at the end of the first heating section is controlled to be ≤1040℃; the temperature at the end of the second heating section is controlled to be 1160-1200℃; the sum of the time of the second heating section and the soaking section is controlled to be ≤110min, and the casting blank discharge temperature is controlled to be 1170-1210℃; ② if Ni alloy is added, 0.08-0.10% is preferably added, and in this case, the discharge temperature is controlled to be 1190-1230℃.

[0049] The steel billet is rolled into hot-rolled plates with a thickness of 3-16mm through two stages of rough rolling and finish rolling. The rough rolling opening temperature is 1020-1080℃, and the finish rolling adopts large reduction, when H≥12mm, the intermediate blank thickness is 58-60mm; the finish rolling final rolling temperature and coiling temperature are set according to the thickness gradient, when 3≤H<8mm, the final rolling temperature is 840-880℃; when 8≤H<12, the final rolling temperature is 820-860℃; when 12≤H≤16, the final rolling temperature is 800-840, and after rolling, laminar cooling is carried out, when H<8mm, the coiling temperature is 600-640℃; when 8≤H<12, the coiling temperature is 570-610℃; when 12≤H≤16, the coiling temperature is 540-580℃.

[0050] If edge crack occurs during rolling, when the edge crack is less than 8mm from the edge, the rolling is widened by 5-10mm; when the edge crack is 8-15mm from the edge, the rolling is widened by 10-15mm (not including 10mm).

[0051] 3) Finishing

[0052] For steel strips with a thickness of ≤6mm, large rolling force is used for flattening, the flattening force is 300-400t, and the bending roll force is 25-35KN.

[0053] The present application will be described in detail below in combination with examples.

[0054] The chemical composition and weight percentage of the steel in each embodiment and comparative example are shown in Table 1, with the balance being iron and inevitable impurities. Comparative Example 5 only added 0.05% Ni, the edge crack sensitivity coefficient A value was 10.8, and the low-temperature fast heating process was not performed, and the quality of the hot curling portion was poor.

[0055] Table 1 Chemical composition of the examples and comparative examples

[0056]

[0057] The main rolling process parameters of the steel in each embodiment and comparative example are shown in Table 2, the mechanical properties are shown in Table 3, and the sulfuric acid corrosion resistance is shown in Table 4.

[0058] Although the mechanical properties of Comparative Example 8 and Comparative Example 9 can also have the high strength and plasticity advantage in the present application, since the finish rolling / coiling-thickness gradient matching system is not implemented, the mechanical property indicators of different thicknesses differ greatly, the yield strength R eL of Comparative Example 8 and Comparative Example 9 differ by 83 MPa, the tensile strength R m differs by 80 MPa, and it is difficult to achieve stability control of the mechanical properties of different thicknesses.

[0059] Table 2 Main process parameters of the rolling process of the examples and comparative examples

[0060]

[0061] Table 3 Mechanical properties and corrosion properties of the examples and comparative examples

[0062]

[0063]

[0064] Table 4 Corrosion properties of the examples and comparative examples

[0065]

[0066]

[0067] The above detailed description of the reference embodiments of the corrosion-resistant steel for sulfuric acid transport tank cars and the manufacturing method thereof is illustrative rather than limiting, and several embodiments can be listed within the defined range, so changes and modifications that do not deviate from the overall concept of the present application should be within the scope of protection of the present application.

Claims

1. A corrosion resistant steel for a sulfuric acid transport tank car, characterized by, The corrosion-resistant steel comprises the following chemical components in percentage by weight: C: 0.11-0.13%; Si: 0.70-0.90%; Mn: 0.70-1.10%; P: ≤0.010%; S: 0.005-0.015%; Cr: 0.60-0.80%; Cu: 0.22-0.35%; Alt: ≤0.005%; Ti: 0.025-0.045%; Mo ≤0.20%; Sb: 0.11-0.15%, and the balance being Fe and inevitable inclusions; The manufacturing method of the corrosion-resistant steel for sulfuric acid transport tank car comprises the following steps: heating, controlled rolling, controlled cooling, coiling, and finishing. In the heating step, the temperature at the end of the first heating section is controlled to be ≤1040℃, the temperature at the end of the second heating section is controlled to be 1160-1200℃, the sum of the time of the second heating section and the soaking section is controlled to be ≤110min, and the casting blank discharge temperature is controlled to be 1170-1210℃. In the controlled rolling step, the rough rolling open rolling temperature is 1020-1080℃; for the hot-rolled plate with a thickness of 3mm≤thickness<8mm, the finish rolling temperature is 840-880℃; for the hot-rolled plate with a thickness of 8mm≤thickness<12mm, the finish rolling temperature is 820-860℃; for the hot-rolled plate with a thickness of 12mm≤thickness≤16mm, the finish rolling temperature is 800-840℃; and after rolling, laminar cooling is performed. In the coiling step, for the hot-rolled plate with a thickness of 3mm≤thickness<8mm, the coiling temperature is 600-640℃; for the hot-rolled plate with a thickness of 8mm≤thickness<12mm, the coiling temperature is 570-610℃; and for the hot-rolled plate with a thickness of 12mm≤thickness≤16mm, the coiling temperature is 540-580℃.

2. The corrosion resistant steel for sulfuric acid transport tank cars defined in claim 1, characterized by, The corrosion-resistant steel further comprises Ni in a percentage by weight of 0.08-0.10%, and A=(C+Cu+Sb) / Ni≤7.

3. The corrosion resistant steel for sulfuric acid transport tank cars according to claim 1 or 2, characterized in that, The metallographic structure of the corrosion-resistant steel is ferrite and pearlite structure.

4. The corrosion resistant steel for sulfuric acid transport tank cars according to claim 1 or 2, characterized by, R eL ≥ 420 MPa, R m 600~750 MPa, A≥25%, yield ratio less than 0.75; relative corrosion rate of Q345B respectively ≤2%, ≤20%, ≤80% after 24h immersion in 20℃, 20% H2SO4; 70℃, 50% H2SO4; 40℃, 98% H2SO4 respectively.

5. The method of producing a corrosion-resistant steel for sulfuric acid transport tank cars according to any one of claims 1 to 4, characterized by, The manufacturing method comprises the following steps: heating, controlled rolling, controlled cooling, coiling, and finishing.

6. The production method according to claim 5, wherein When the casting blank width is 2000-2150mm, the casting blank pulling speed is 0.95-1.00m / min; when the casting blank width is 1500-2000mm, the casting blank pulling speed is 1-1.25m / min; and when the casting blank width is 950-1500mm, the casting blank pulling speed is 1.25-1.30m / min; the casting blank is avoided to be hoisted at 600 and 800℃, and the casting blank straightening temperature is ≥850℃.

7. The production method according to claim 5, wherein In the heating step, when the steel contains Ni, the discharge temperature is controlled to be 1190-1230℃.

8. The production method according to claim 5, wherein In the finishing step, for the steel strip with a thickness of ≤6mm, the flattening force is 300-400t, and the bending roll force is 25-35KN.

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