High-corrosion-resistance high-toughness weathering-resistant steel and preparation method thereof

Abstract

The invention provides high-corrosion-resistance high-toughness weathering steel and a preparation method thereof, and relates to the technical field of metallurgy. The high-corrosion-resistance high-toughness weathering-resistant steel comprises the following chemical components in percentage by weight: less than or equal to 0.06% of C, 0.25%-0.45% of Si, 0.30%-0.50% of Mn, less than or equal to 0.015% of P, less than or equal to 0.008% of S, 3.60%-3.90% of Cr, 0.30%-0.50% of Ni, 0.30%-0.40% of Cu and the balance of Fe. And the balance of Fe and inevitable impurities. The high-corrosion-resistance and high-toughness weathering resistant steel has the advantages of high corrosion resistance and high toughness, can meet the comprehensive requirements of various industries on atmospheric corrosion resistance and steel mechanical properties, and has wide popularization and application prospects.

Description

[Technical field]

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

[0002] With the development of modern society, steel production has provided possibilities for infrastructure construction and industrial development. Steel has become the most used metal material by humans. Steel is widely used in road facility support structures and bridges, ships, car bodies and other products. It has the advantages of high strength, good plasticity and strong toughness. However, due to long-term exposure to the atmosphere, steel is prone to corrosion, and the loss caused should not be underestimated. Compared with ordinary carbon steel, 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. In engineering applications, various structural parts are affected by the changing atmospheric environment. Corrosion leads to weakening of the cross section of the components and decrease of ductility, which reduces the durability of the structure and buries hidden dangers for safety. In order to meet the increasingly high mechanical performance requirements of structural parts and further extend the service life, it is urgent to develop new high-corrosion-resistant and high-toughness weathering steel. By improving the atmospheric corrosion resistance of steel, the service life of structural parts can be extended to meet the increasingly stringent requirements of materials in industries such as roads, bridges and vehicles.

[0003] Therefore, it is necessary to study a high corrosion-resistant and high-toughness weathering steel 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-corrosion-resistant and high-toughness weathering steel and a preparation method thereof. The high-corrosion-resistant and high-toughness weathering steel has the advantages of high corrosion resistance and high toughness, can meet the comprehensive requirements of various industries for atmospheric corrosion resistance and steel mechanical properties, and has broad prospects for promotion and application.

[0005] On the one hand, the present invention provides a high corrosion-resistant and high-toughness weathering steel, the chemical composition of which includes, by weight percentage, C≤0.06%, Si: 0.25%~0.45%, Mn: 0.30%~0.50%, P≤0.015%, S≤0.008%, Cr: 3.60~3.90%, Ni: 0.30~0.50%, Cu: 0.30~0.40%; 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 effective content of Cu+Ni+Cr in the chemical composition of the high corrosion-resistant and high-toughness weathering steel is ≥4.4%.

[0007] According to the above aspects and any possible implementation, there is further provided an implementation, wherein the structure of the weathering steel includes a composite phase structure of ferrite, pearlite and bainite.

[0008] According to the above aspects and any possible implementation, there is further provided an implementation, wherein the volume fraction of ferrite in the weathering steel is 25-30%.

[0009] According to the above aspects and any possible implementation, there is further provided an implementation, wherein the volume fraction of pearlite in the weathering steel is 40-45%.

[0010] According to the above aspects and any possible implementation, an implementation is further provided, wherein the volume fraction of bainite in the weathering steel is 35-45%.

[0011] According to the aspects described above and any possible implementation method, an implementation method is further provided, wherein the yield strength of the weathering steel is ≥430MPa, the tensile strength is ≥650MPa, the elongation after fracture is ≥20%, the atmospheric corrosion resistance index is ≥10.0; and the V-notch impact energy is ≥280J at -40°C.

[0012] According to the aspects described above and any possible implementation methods, a method for preparing high-corrosion-resistant, high-toughness and weathering-resistant steel is further provided. The preparation method smelts the raw materials into steel billets according to the chemical composition and proportion of any one of the high-corrosion-resistant, high-toughness and weathering-resistant steels, and obtains the finished product after two-stage rolling and controlled cooling processes.

[0013] According to the above aspects and any possible implementation, an implementation is further provided, in the two-stage rolling process, the heating temperature of the steel billet is 1180-1220° C., and the heat preservation time is 60 min-120 min, wherein;

[0014] The starting rolling temperature of the rough rolling is 1100-1140°C, the final rolling temperature is 1050-1090°C, and the rough rolling reduction is greater than 60%;

[0015] The starting rolling temperature of the finishing rolling is 880-920°C, and the final rolling temperature is 850-890°C.

[0016] According to the above aspects and any possible implementation, an implementation is further provided, in which in the controlled cooling process, after finishing rolling, water is sprayed to cool to a final cooling temperature of 650-700°C, and after final cooling, air cooling is used to cool to room temperature.

[0017] Compared with the prior art, the present invention can achieve the following technical effects:

[0018] The high corrosion-resistant and high-toughness weathering steel disclosed in the present invention has reduced S and P contents and increased Cr content on the basis of low carbon to improve atmospheric corrosion resistance. The yield strength is ≥430MPa, the tensile strength is ≥650MPa, and the atmospheric corrosion resistance index is ≥10.0. The atmospheric corrosion resistance is improved by more than 70% compared with carbon steel. The steel has the advantages of high corrosion resistance and high toughness, can meet the comprehensive requirements of various industries for atmospheric corrosion resistance and mechanical properties of steel, and has broad prospects for promotion and application.

[0019] 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

[0020] 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.

[0021] Figure 1 It is a flow chart of a method for preparing high corrosion-resistant and high-toughness weathering steel provided by an embodiment of the present invention. [Specific implementation method]

[0022] 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.

[0023] 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.

[0024] 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.

[0025] The invention provides a high corrosion resistance and high toughness weathering steel, the chemical composition of which includes C≤0.06%, Si: 0.25%-0.45%, Mn: 0.30%-0.50%, P≤0.015%, S≤0.008%, Cr: 3.60-3.90%, Ni: 0.30-0.50%, Cu: 0.30-0.40% by weight; the rest is Fe and inevitable impurities. The structure of the weathering steel includes ferrite, pearlite and bainite, the volume fraction of ferrite is 25-30%, the volume fraction of pearlite is 40-45%, and the volume fraction of bainite is 35-45%.

[0026] The yield strength of weathering steel is ≥430MPa, the tensile strength is ≥650MPa, the elongation after fracture is ≥20%, the atmospheric corrosion resistance index is ≥10.0, and the V-notch impact energy is ≥280J at -40℃.

[0027] Functions and contents of the chemical components of the present invention:

[0028] C is an important element for solid solution strengthening in steel. Increasing carbon content can improve strength, but while increasing C content improves steel strength, it also brings certain negative effects, such as reducing corrosion resistance and toughness of steel, deteriorating welding performance, and damaging ductility. The C content in steel should be controlled to ≤0.06%.

[0029] Si is a commonly used deoxidizing element in the steelmaking process, and it also has a great influence on the performance of steel. Si in steel can improve strength and hardenability, and refine internal grains, but when the Si content is high, it will reduce the toughness of the steel, so the Si content is controlled to 0.25% to 0.45%.

[0030] Mn can improve the hardenability of steel, improve hot working performance, and also improve the strength of steel. Since it can combine with S to form MnS, it can improve the adverse effects of S on steel. However, when the Mn content is high, it deteriorates the welding performance and reduces the plasticity index of steel, so the Mn content is controlled to 0.30% to 0.50%.

[0031] P element can make steel produce "cold brittleness" phenomenon, and steel becomes obviously brittle at low temperature. P element can improve strength and corrosion resistance, but will reduce impact toughness and plasticity. Therefore, the P content in steel is controlled to be ≤0.015%.

[0032] The S element can make steel "hot brittle" and reduce the toughness and atmospheric corrosion resistance of steel. At the same time, in order to improve the purity of molten steel, the S element is strictly controlled to ≤ 0.008%.

[0033] Cr can significantly improve the atmospheric corrosion resistance of steel, form an oxide film, promote the formation of spinel oxides, and improve the atmospheric corrosion resistance of steel. Chromium forms a passivation film on the surface of steel, significantly improving the corrosion resistance of steel; but when carbides containing chromium precipitate, the corrosion resistance of steel decreases. In addition, Cr increases the strength and hardness of steel and significantly increases the tough-brittle transition temperature of steel. Chromium is prone to form dendritic segregation, reducing the plasticity of steel. Therefore, the Cr content is controlled to be 3.60-3.90%.

[0034] The Ni element can improve the atmospheric corrosion resistance of steel, improve the strength and toughness of steel, and increase the self-corrosion potential of steel. Considering the scarcity and cost of the Ni element, the Ni content is controlled to be 0.30-0.50%.

[0035] The Cu element increases the strength of steel and can significantly improve the corrosion resistance of steel. When the content is high, the steel will become copper brittle during hot working. Therefore, the Cu content is controlled to be 0.30-0.40%.

[0036] like Figure 1 As shown, the present invention also discloses a preparation method of the above-mentioned high corrosion-resistant and high-toughness weathering steel. The specific preparation method includes smelting the raw materials into steel billets according to the chemical composition and proportion of the above-mentioned high corrosion-resistant and high-toughness weathering steel, and obtaining the finished product after two-stage rolling and controlled cooling processes in sequence.

[0037] In the two-stage rolling process, the heating temperature of the steel billet is 1180-1220°C and kept warm for 1-2 hours.

[0038] In the two-stage rolling process, the starting rolling temperature of rough rolling is 1100-1140°C, the final rolling temperature is 1050-1090°C, and the rough rolling reduction is greater than 60%; the starting rolling temperature of fine rolling is 880-920°C, and the final rolling temperature is 850-890°C.

[0039] In the controlled cooling process, after finishing rolling, water is sprayed to cool to the final cooling temperature of 650-700°C, and after final cooling, slow cooling is adopted to room temperature.

[0040] Example 1

[0041] High corrosion resistance and high toughness weathering steel, its chemical composition by weight percentage includes: C0.05%, Si0.27%, Mn0.44%, S0.003%, P0.014%, Cr3.61%, Ni0.31%, Cu0.32%; the rest is Fe and inevitable impurities. The raw materials are smelted into steel billets according to the above chemical composition and ratio; then two-stage rolling is carried out, the heating temperature is 1205℃, and the heat preservation is 70 minutes. The starting rolling temperature of rough rolling is 1136℃, the final rolling temperature is 1060℃, and the rough rolling reduction is 61%; the starting rolling temperature of finishing rolling is 905℃, and the final rolling temperature is 882℃. After finishing rolling, water spray cooling is carried out to the final cooling temperature of 675℃. The performance indicators of the finished weathering steel are tested, and its yield strength is 445MPa, the tensile strength is 665MPa, and the V-notch impact energy is 288J at -40℃.

[0042] The atmospheric corrosion resistance test was carried out, and carbon steel Q345B was used as the comparison steel. Three parallel samples were prepared for each group. The solution used was NaHSO3 solution with a concentration of (1±0.05)×10 -2 mol / L, pH value is between 4.4 and 4.8; the replenishing solution is NaHSO3 solution with a concentration of 2x10 -2 mol / L, 3L of replenishing solution is added every day. The solution temperature is 45±2℃ to simulate high temperature environment. The humidity is 70±5% to simulate high humidity environment. The baking lamp is turned on for 24 hours, and the highest surface temperature of the sample after baking is 70±10℃ to simulate strong radiation environment; to simulate the alternating dry and wet environment, 60±3min is set as a cycle, of which the immersion time is 12±1.5min, and a 72h cycle immersion corrosion test is carried out. The corrosion rate is obtained by calculating the corrosion weight loss per unit area of ​​the sample, and then the relative corrosion rate of the relative comparison steel is obtained. The test results are shown in Table 1.

[0043] Example 2

[0044] High corrosion resistance and high toughness weathering steel, its chemical composition by weight percentage includes: C0.04%, Si0.30%, Mn0.41%, S0.004%, P0.013%, Cr3.65%, Ni0.35%, Cu0.34%; the rest is Fe and inevitable impurities. The raw materials are smelted into steel billets according to the above chemical composition and ratio; then two-stage rolling is carried out, the heating temperature is 1192℃, and the heat preservation is 78 minutes. The starting rolling temperature of rough rolling is 1128℃, the final rolling temperature is 1075℃, and the rough rolling reduction is 63%; the starting rolling temperature of finishing rolling is 896℃, and the final rolling temperature is 873℃. After finishing rolling, water spray cooling is carried out to the final cooling temperature of 666℃. The performance indicators of the finished weathering steel are tested, and its yield strength is 462MPa, the tensile strength is 680MPa, and the V-notch impact energy is 293J at -40℃.

[0045] The atmospheric corrosion resistance test was carried out as described in Example 1.

[0046] Example 3

[0047] High corrosion resistance and high toughness weathering steel, its chemical composition by weight percentage includes: C0.06%, Si0.36%, Mn0.45%, S0.003%, P0.012%, Cr3.81%, Ni0.39%, Cu0.35%; the rest is Fe and inevitable impurities. The raw materials are smelted into steel billets according to the above chemical composition and ratio; then two-stage rolling is carried out, the heating temperature is 1187℃, and the heat preservation is 88 minutes. The starting rolling temperature of rough rolling is 1118℃, the final rolling temperature is 1055℃, and the rough rolling reduction is 62%; the starting rolling temperature of finishing rolling is 886℃, and the final rolling temperature is 854℃. After finishing rolling, water spray cooling is carried out to the final cooling temperature of 652℃. The performance indicators of the finished weathering steel are tested, and its yield strength is 440MPa, the tensile strength is 676MPa, and the V-notch impact energy is 285J at -40℃.

[0048] The atmospheric corrosion resistance test was carried out as described in Example 1.

[0049] The ingredients in the examples and comparative examples are tabulated.

[0050] Table 1 Test results of atmospheric corrosion resistance of steel in Example 1-3

[0051]

[0052] In summary, the high corrosion-resistant and high-toughness weathering steel prepared by the present invention has a yield strength of more than 430MPa, a tensile strength of more than 650MPa, an atmospheric corrosion resistance index ≥10.0, and a V-notch impact energy ≥280J at -40°C. The atmospheric corrosion resistance comparison test also shows that the atmospheric corrosion resistance weight loss rate of the invented steel is less than 30% of that of carbon steel Q345B, and the atmospheric corrosion resistance is improved by more than 70% relative to carbon steel Q345B, with excellent comprehensive performance, meeting the increasingly stringent use requirements of materials in industries such as roads, bridges and vehicles.

[0053] The above is a detailed introduction to a high corrosion-resistant and high-toughness weathering steel and its preparation method provided by 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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 corrosion-resistant and high-toughness weathering steel, characterized in that: The chemical composition of the high corrosion-resistant and high-toughness weathering steel includes, by weight percentage, C≤0.06%, Si: 0.25%~0.45%, Mn: 0.30%~0.50%, P≤0.015%, S≤0.008%, Cr: 3.60~3.90%, Ni: 0.30~0.50%, Cu: 0.30~0.40%; the rest is Fe and unavoidable impurities.

2. The high corrosion-resistant and high-toughness weathering steel according to claim 1 is characterized in that: In the chemical composition of the highly corrosion-resistant and highly tough weathering steel, the effective content of Cu+Ni+Cr is ≥4.4%.

3. The high corrosion-resistant and high-toughness weathering steel according to claim 1, characterized in that: The structure of the weathering steel includes a composite phase structure of ferrite, pearlite and bainite.

4. The high corrosion-resistant and high-toughness weathering steel according to claim 3 is characterized in that: The ferrite volume fraction of the weathering steel is 25-30%.

5. The high corrosion-resistant and high-toughness weathering steel according to claim 3 is characterized in that: The pearlite volume fraction of the weathering steel is 40-45%.

6. The high corrosion-resistant and high-toughness weathering steel according to claim 3, characterized in that: The volume fraction of bainite in the weathering steel is 35-45%.

7. The high corrosion-resistant and high-toughness weathering steel according to claim 1, characterized in that: The weathering steel has a yield strength of ≥430MPa, a tensile strength of ≥650MPa, an elongation after fracture of ≥20%, an atmospheric corrosion resistance index of ≥10.0, and a V-notch impact energy of ≥280J at -40°C.

8. A method for preparing high corrosion-resistant and high-toughness weathering steel, characterized in that: The preparation method smelts the raw materials into steel billets according to the chemical composition and proportion of the high corrosion-resistant and high-toughness weathering steel in any one of claims 1 to 7, and obtains the finished product through two-stage rolling and controlled cooling processes.

9. The preparation method according to claim 8, characterized in that: In the two-stage rolling process, the heating temperature of the steel billet is 1180-1220°C and the heat preservation time is 60min-120min, wherein; The starting rolling temperature of the rough rolling is 1100-1140°C, the final rolling temperature is 1050-1090°C, and the rough rolling reduction is greater than 60%; The starting rolling temperature of the finishing rolling is 880-920°C, and the final rolling temperature is 850-890°C.

10. The preparation method according to claim 8, characterized in that: In the controlled cooling process, after finishing rolling, water is sprayed to cool to a final cooling temperature of 650-700° C., and after final cooling, air cooling is adopted to cool to room temperature.

Images