Chloride ion corrosion-resistant high-strength weather-resistant steel and preparation method thereof

Abstract

The invention provides chloride ion corrosion-resistant high-strength weather-resistant steel and a preparation method thereof, and relates to the technical field of ferrous metallurgy. The invention provides high-strength weather-resistant steel resistant to chloride ion corrosion. The high-strength weather-resistant steel comprises the following chemical components in percentage by weight: less than or equal to 0.10% of C, 0.30%-0.50% of Si, 0.80%-1.00% of Mn, less than or equal to 0.010% of P, less than or equal to 0.010% of S, 2.80%-3.00% of Ni, 0.20%-0.35% of Cu, 0.0030%-0.0050% of Nb and the balance of Fe. And the balance of Fe and inevitable impurities. The chloride ion corrosion resistance of the high-strength weather-resistant steel is doubled compared with that of traditional weather-resistant steel, and the high-strength weather-resistant steel has the advantages of being high in strength and corrosion resistance, especially chloride ion corrosion resistance, not only can meet the requirements of infrastructures for the mechanical property of steel, but also has excellent corrosion resistance of chloride ion corrosion resistance, and has wide application and popularization prospects.

Description

[Technical field]

[0001] The invention relates to the technical field of iron and steel metallurgy, and in particular to a high-strength weathering steel resistant to chloride ion corrosion and a preparation method thereof. [Background technology]

[0002] Compared with ordinary carbon steel, traditional weathering steel usually adds corrosion-resistant elements such as Cr, Ni, Mo and Cu to improve its corrosion resistance in the atmospheric environment. Weathering steel is widely used in various fields of national construction due to its good atmospheric corrosion resistance. However, in engineering applications such as marine engineering structures and some road facilities, due to the rich chloride ions in the marine atmospheric environment and road snow melting agents, traditional weathering steel does not show more obvious corrosion resistance than carbon steel. It is precisely because this type of equipment structure is used in such a harsh and complex corrosive environment that higher requirements are placed on the corrosion resistance of the material, especially the resistance to chloride ion corrosion.

[0003] Therefore, it is necessary to study a high-strength weathering steel resistant to chloride ion corrosion and a preparation method thereof to address the deficiencies of the prior art and to solve or alleviate one or more of the above problems. [Summary of the invention]

[0004] In view of this, the present invention provides a high-strength weathering steel resistant to chloride ion corrosion and a preparation method thereof. The chloride ion corrosion resistance of the high-strength weathering steel is doubled compared with that of traditional weathering steel. It has the advantages of high strength, high corrosion resistance, especially resistance to chloride ion corrosion. It can not only meet the requirements of infrastructure for the mechanical properties of steel, but also has excellent corrosion resistance to chloride ion corrosion, and has broad prospects for promotion and application.

[0005] On the one hand, the present invention provides a high-strength weathering steel resistant to chloride ion corrosion. The chemical composition of the high-strength weathering steel includes, by weight percentage, C≤0.10%, Si: 0.30%~0.50%, Mn: 0.80%~1.00%, P≤0.010%, S≤0.010%, Ni: 2.80~3.00%, Cu: 0.20~0.35%, Nb: 0.0030~0.0050%; the rest is Fe and unavoidable impurities.

[0006] According to the above aspects and any possible implementation, an implementation is further provided, in which the chemical composition of the high-strength weathering steel is 0.35%≥Cu+Nb≥0.3%.

[0007] According to the above aspects and any possible implementation, there is further provided an implementation, in which the structure of the weathering steel is granular bainite.

[0008] According to the aspects described above and any possible implementation method, an implementation method is further provided, wherein the specified plastic extension strength Rp0.2 of the weathering steel is ≥470MPa, the tensile strength is ≥760MPa, the elongation after fracture is ≥25%, the atmospheric corrosion resistance index is ≥11.0; and the V-notch impact energy is ≥55J at -40°C.

[0009] According to the aspects described above and any possible implementation methods, a method for preparing high-strength weather-resistant steel resistant to chloride ion corrosion is further provided. The preparation method smelts the raw materials into steel billets according to the chemical composition and proportion of the high-strength weather-resistant steel, and obtains the finished product after the processes of controlled rolling, controlled cooling, and curling.

[0010] According to the above aspects and any possible implementation, there is further provided an implementation, in which in the controlled rolling process, the heating temperature of the steel billet is 1170-1200° C. and the heating is kept for 60 minutes.

[0011] According to the above aspects and any possible implementation, there is further provided an implementation, wherein the controlled rolling process includes sequentially performing rough rolling and finish rolling.

[0012] According to the aspects and any possible implementation methods described above, an implementation method is further provided, in which the starting rolling temperature of the rough rolling in the controlled rolling process is 1100-1150°C, and the final rolling temperature is 1000-1050°C; the starting rolling temperature of the finishing rolling is 880-930°C, and the final rolling temperature is 800-830°C.

[0013] According to the above aspects and any possible implementation, an implementation is further provided, wherein in the controlled cooling process, water spray cooling is performed after the finish rolling is completed, and the cooling rate is 20-40°C / s.

[0014] According to the above aspects and any possible implementation, there is further provided an implementation, in which in the curling process, the curling temperature is 530-570°C.

[0015] Compared with the prior art, the present invention can achieve the following technical effects:

[0016] The high-strength weathering steel resistant to chloride ion corrosion disclosed in the present invention has an increased Ni element content, a small amount of ferroniobium is added, and a hot rolling process is adopted. The plastic elongation strength Rp0.2 is specified to be ≥470MPa, the tensile strength is ≥760Mpa, and the atmospheric corrosion resistance index is ≥11.0. The chloride ion corrosion resistance is doubled compared with traditional weathering steels. The steel has the advantages of high strength, high corrosion resistance, especially chloride ion corrosion resistance. The steel can not only meet the requirements of infrastructure for the mechanical properties of steel, but also has excellent corrosion resistance to chloride ion corrosion, and has broad application prospects.

[0017] Of course, any product implementing the present invention does not necessarily need to achieve all of the above-mentioned technical effects at the same time.

Brief Description of the Drawings

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 It is a flow chart of a method for preparing high-strength weathering steel provided in one embodiment of the present invention. [Specific implementation method]

[0020] In order to better understand the technical solution of the present invention, the embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0021] It should be clear that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms "a", "said" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0023] The invention provides a high-strength weathering steel resistant to chloride ion corrosion, wherein the chemical composition includes C≤0.10%, Si: 0.30%-0.50%, Mn: 0.80%-1.00%, P≤0.010%, S≤0.010%, Ni: 2.80-3.00%, Cu: 0.20-0.35%, Nb: 0.0030-0.0050% by weight; the rest is Fe and unavoidable impurities. The structure of the weathering steel is granular bainite. The specified plastic extension strength Rp0.2 of the weathering steel is ≥470MPa, the tensile strength is ≥760MPa, the elongation after fracture is ≥25%, the atmospheric corrosion resistance index is ≥11.0; the V-notch impact energy is ≥55J at -40°C.

[0024] Effects and contents of chemical components of the present invention: The increase of C element can improve the strength of steel, but it will also reduce the corrosion resistance, welding performance and toughness of steel. Therefore, the carbon content in the steel should be controlled, and the C content in the present invention is ≤0.10%.

[0025] Si is the most common alloying element in steel. Silicon is a good deoxidizer in the steel smelting process. It can deoxidize and remove impurities and purify molten steel. In addition, it can mainly refine the grains and improve the strength, hardenability and magnetism of steel. However, if the silicon content is too high, the toughness and welding performance of the steel will be reduced, so the content is controlled to be 0.30% to 0.50%.

[0026] Mn can improve the strength of steel: Since Mn is relatively cheap and can be infinitely dissolved in Fe, it has a relatively small effect on plasticity while improving the strength of steel. Mn improves the hardenability of steel and improves the hot working performance of steel. Mn can eliminate the influence of S (sulfur). The higher the Mn content, the better. The increase in manganese content will reduce the plasticity and welding performance of steel. Therefore, the content of Mn is controlled to be 0.80% to 1.00%.

[0027] Although the phosphorus element can increase the strength and weather resistance of steel, it causes a significant decrease in plasticity and impact toughness. Especially at low temperatures, it makes the steel significantly brittle, a phenomenon called "cold brittleness". Cold brittleness deteriorates the cold processing and weldability of steel. The higher the phosphorus content, the greater the cold brittleness. Therefore, the phosphorus content in steel is strictly controlled, and its content is P≤0.010%.

[0028] S is a harmful element in steel. When hot working steel, premature melting of FeS compounds causes cracking, a phenomenon called "hot brittleness". S reduces the ductility and toughness of steel and causes cracks during rolling. S is also detrimental to welding performance and reduces corrosion resistance. Therefore, the content of S is controlled to ≤0.010%.

[0029] The Ni element can improve the strength, toughness and corrosion resistance of steel. Adding the alloying element Ni to steel can shift its self-corrosion potential positively, thereby increasing its stability. Increasing the Ni element in the steel can enrich the Ni element in the rust layer, refine the rust layer grains, increase the density, and generate a rust layer with a protective function. Therefore, it is difficult for chloride ions to pass through the rust layer and contact the steel matrix, thereby reducing the corrosion rate of weathering steel. Due to the presence of Ni in the steel, the formation of nano-phase, superparamagnetic α-FeOOH in the inner rust layer is promoted, the density of the inner rust layer is increased, and the ability to resist chloride ion corrosion is improved. However, Ni will increase the brittleness of steel. Combined with cost control, the Ni content is 2.80-3.00%.

[0030] The prominent role of Cu in steel is to improve the atmospheric corrosion resistance of low alloy steel. Adding Cu can also improve the strength of steel. When the content is high, it is not conducive to hot deformation processing and causes copper brittleness during hot deformation processing. Therefore, the Cu content is controlled to 0.20-0.35%.

[0031] The Nb element is used to fix the carbon in the alloy steel, so that it forms stable carbides to reduce the harmful effects of carbon on the corrosion resistance of the alloy steel. In addition, trace amounts of Nb can refine the grain size of the steel structure and improve the plasticity, toughness and strength of the material; but if the niobium content is too high, the casting is prone to surface cracks and the welding performance is reduced. Therefore, the Nb content is controlled to 0.0030-0.0050%.

[0032] like Figure 1 As shown, the present invention also discloses a preparation method of the above-mentioned high-strength weather-resistant steel resistant to chloride ion corrosion. The specific production method includes smelting the raw materials into steel billets according to the chemical composition and proportion of the above-mentioned high-strength weather-resistant steel resistant to chloride ion corrosion, and obtaining the finished product after the steps of controlled rolling, controlled cooling, and curling in sequence.

[0033] In the controlled rolling process, the billet is heated to a temperature of 1170-1200°C and kept at that temperature for 60 minutes.

[0034] In the controlled rolling process, the starting rolling temperature of rough rolling is 1100-1150°C, and the final rolling temperature is 1000-1050°C; the starting rolling temperature of finish rolling is 880-930°C, and the final rolling temperature is 800-830°C.

[0035] In the controlled cooling process, water is sprayed for cooling after finishing rolling, and the cooling rate is 20-40℃ / s.

[0036] In the curling process, the curling temperature is 530 to 570°C.

[0037] Example 1

[0038] The chemical composition of high-strength weathering steel resistant to chloride ion corrosion includes, by weight percentage, C0.082%, Si0.41%, Mn0.91%, S0.006%, P0.006%, Ni2.95%, Cu0.28%, Nb0.0039%; the rest is Fe and unavoidable impurities. The raw materials are smelted into steel billets according to the above chemical composition and proportion; then controlled rolling is carried out, the heating temperature is 1198℃, and the temperature is kept for 60 minutes. The starting rolling temperature of rough rolling is 1126℃, and the final rolling temperature is 1030℃; the starting rolling temperature of finishing rolling is 925℃, and the final rolling temperature is 816℃. After finishing rolling, water spray cooling is carried out, and the cooling rate is 31℃ / s. The curling temperature is 556℃. The performance indicators of the finished weathering steel were tested, and the specified plastic extension strength Rp0.2 was 490MPa, the tensile strength was 778MPa, and the V-notch impact energy at -40℃ was 58J.

[0039] The chloride ion corrosion resistance test was carried out, and the traditional weathering steel Q450NR1 was used as the comparison steel. To simulate the high chloride ion environment, 2% NaCl solution was selected as the immersion solution, and 500ml of deionized water was added to each tank every day to supplement the evaporation of the solution water. The solution temperature was 45±2℃ to simulate the high temperature environment. The humidity was 70±5% to simulate the high humidity environment. The baking lamp was turned on for 24 hours, and the maximum surface temperature of the sample after baking was 70±10℃ to simulate the strong radiation environment; to simulate the dry-wet alternating environment, 60±3min was set as a cycle, of which the immersion time was 12±1.5min, and a 96h cycle immersion corrosion test was carried out. Three parallel samples were prepared for each group, and the corrosion rate was obtained by calculating the corrosion weight loss per unit area of ​​the sample, and then the relative corrosion rate of the relative comparison steel was obtained. The test results are shown in Table 1.

[0040] Example 2

[0041] The chemical composition of high-strength weathering steel resistant to chloride ion corrosion includes, by weight percentage: C0.09%, Si0.46%, Mn0.93%, S0.007%, P0.008%, Ni2.88%, Cu0.26%, Nb0.0033%; the rest is Fe and unavoidable impurities. The raw materials are smelted into steel billets according to the above chemical composition and proportion; then controlled rolling is carried out, the heating temperature is 1185℃, and the temperature is kept for 60 minutes. The starting rolling temperature of rough rolling is 1135℃, and the final rolling temperature is 1046℃; the starting rolling temperature of fine rolling is 906℃, and the final rolling temperature is 823℃. After fine rolling, water spray cooling is carried out, and the cooling rate is 36℃ / s. The curling temperature is 548℃. The performance indicators of the finished weathering steel were tested, and the specified plastic extension strength Rp0.2 was 502MPa, the tensile strength was 772MPa, and the V-notch impact energy was 60J at -40℃.

[0042] The chloride ion corrosion resistance test was carried out in the same manner as described in Example 1.

[0043] Example 3

[0044] The chemical composition of high-strength weathering steel resistant to chloride ion corrosion includes, by weight percentage: C0.07%, Si0.36%, Mn0.88%, S0.008%, P0.008%, Ni2.91%, Cu0.32%, Nb0.0045%; the rest is Fe and unavoidable impurities. The raw materials are smelted into steel billets according to the above chemical composition and proportion; then controlled rolling is carried out, the heating temperature is 1185℃, and the temperature is kept for 60 minutes. The starting rolling temperature of rough rolling is 1140℃, and the final rolling temperature is 1025℃; the starting rolling temperature of finishing rolling is 895℃, and the final rolling temperature is 820℃. After finishing rolling, water spray cooling is carried out, and the cooling rate is 25C / s. The coiling temperature is 536℃. The performance indicators of the finished weathering steel were tested, and the specified plastic extension strength Rp0.2 was 510MPa, the tensile strength was 785MPa, and the V-notch impact energy at -40℃ was 61J.

[0045] The chloride ion corrosion resistance test was carried out in the same manner as described in Example 1.

[0046] Table 1 Chloride ion corrosion resistance test results of steel in Example 1-3

[0047]

[0048] In summary, the high-strength weathering steel resistant to chloride ion corrosion prepared by the present invention has a plastic extension strength Rp0.2 of 470MPa or more, a tensile strength of 760MPa or more, an atmospheric corrosion resistance index ≥11.0, and a V-notch impact energy ≥55J at -40°C. The chloride ion corrosion resistance comparison test also shows that the chloride ion corrosion resistance of the invented steel is more than doubled compared with the traditional high-strength weathering steel Q450NR1, and the comprehensive performance is excellent, meeting the anti-corrosion requirements of chloride ion-rich environments such as marine atmosphere and road snow melting agents.

[0049] The above is a detailed introduction to a high-strength weathering steel resistant to chloride ion corrosion and a preparation method thereof provided in the embodiments of the present application. The description of the above embodiments is only used to help understand the method and its core idea of ​​the present application; at the same time, for those skilled in the art, according to the idea of ​​the present application, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

[0050] For example, certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that hardware manufacturers may use different nouns to refer to the same component. This specification and claims do not use differences in names as a way to distinguish components, but use differences in the functions of components as the criteria for distinction. As mentioned throughout the specification and claims, "including" and "comprising" are open-ended terms, so they should be interpreted as "including / including but not limited to". "Approximately" means that within an acceptable error range, those skilled in the art can solve the technical problem within a certain error range and basically achieve the technical effect. The subsequent description of the specification is a preferred embodiment of the present application, but the description is for the purpose of illustrating the general principles of the present application, and is not used to limit the scope of the present application. The scope of protection of the present application shall be determined by the definition of the attached claims.

[0051] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a product or system including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such a product or system. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the product or system including the elements.

[0052] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0053] The above description shows and describes several preferred embodiments of the present application, but as mentioned above, it should be understood that the present application is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the application concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art do not deviate from the spirit and scope of the present application, and should be within the scope of protection of the claims attached to the present application.

Claims

1. A high-strength weathering steel resistant to chloride ion corrosion, characterized in that: The chemical composition of the high-strength weathering steel includes, by weight percentage, C≤0.10%, Si: 0.30%~0.50%, Mn: 0.80%~1.00%, P≤0.010%, S≤0.010%, Ni: 2.80~3.00%, Cu: 0.20~0.35%, Nb: 0.0030~0.0050%; the rest is Fe and unavoidable impurities.

2. The high-strength weathering steel according to claim 1, characterized in that: In the chemical composition of the high-strength weathering steel, 0.35%≥Cu+Nb≥0.3%.

3. The high-strength weathering steel according to claim 1, characterized in that: The structure of the weathering steel is granular bainite.

4. The high-strength weathering steel according to claim 1, characterized in that: The specified plastic extension strength Rp0.2 of the weathering steel is ≥470MPa, the tensile strength is ≥760MPa, the elongation after fracture is ≥25%, the atmospheric corrosion resistance index is ≥11.0; and the V-notch impact energy is ≥55J at -40°C.

5. A method for preparing high-strength weathering steel resistant to chloride ion corrosion, characterized in that: The preparation method smelts the raw materials into steel billets according to the chemical composition and proportion of any one of the high-strength weathering steels in claims 1 to 3, and obtains the finished product after sequentially undergoing the processes of controlled rolling, controlled cooling, and curling.

6. The preparation method according to claim 5, characterized in that: In the controlled rolling process, the heating temperature of the steel billet is 1170-1200° C. and the temperature is kept for 60 minutes.

7. The preparation method according to claim 5, characterized in that: The controlled rolling process includes performing rough rolling and finish rolling in sequence.

8. The preparation method according to claim 7, characterized in that: In the controlled rolling process, the starting rolling temperature of the rough rolling is 1100-1150°C, and the final rolling temperature is 1000-1050°C; the starting rolling temperature of the finish rolling is 880-930°C, and the final rolling temperature is 800-830°C.

9. The preparation method according to claim 8, characterized in that: In the controlled cooling process, water is sprayed for cooling after finishing rolling, and the cooling rate is 20-40°C / s.

10. The preparation method according to claim 5, characterized in that: In the curling step, the curling temperature is 530 to 570°C.

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