A high-strength stress-corrosion-resistant steel for mine round-link chains and a method for manufacturing the same

Abstract

The application discloses a kind of high-strength mining round-link chain steel resistant to stress corrosion and a preparation method thereof, and belongs to the technical field of round-link chain steel, solve the problem that the strength, toughness, stress corrosion resistance of round-link chain steel in prior art cannot be effectively improved simultaneously.The components of the high-strength mining round-link chain steel resistant to stress corrosion include, by mass percentage: C: 0.22% to 0.27%, Si: 0.10% to 0.17%, Mn: 0.48% to 0.62%, P: ≤0.015%, S: ≤0.005%, Cr: 0.41% to 0.66%, Ni: 0.88% to 1.23%, Mo: 0.41% to 0.58%, Cu: 0.40% to 0.60%, V: 0.18% to 0.36%, W: 0.21% to 0.45%, and the balance is Fe and unavoidable impurities.The high-strength mining round-link chain steel resistant to stress corrosion has high strength, good plasticity and toughness, and excellent stress corrosion resistance.

Description

Technical Field

[0001] This invention relates to the field of steel for circular link chains, and in particular to a high-strength mining circular link chain steel resistant to stress corrosion and its preparation method. Background Technology

[0002] Mining round link chains are the drive chains on scraper conveyors and loaders used in coal mining. They are both critical and vulnerable components. A breakage or failure causing equipment downtime will affect the entire production line and severely impact the coal mining efficiency of the longwall face. With the improvement in the overall performance of materials used in other components of coal mining faces and the trend towards heavier materials, the limitations of round link chain materials restrict the improvement of equipment production capacity and are a significant bottleneck restricting the overall lifespan of scraper conveyors.

[0003] Mining circular link chains are primarily used underground, where corrosive media such as coal dust, rock dust, humid air, and dissolved salts are abundant. The environment is extremely complex and harsh, with both oxygen-rich areas and corrosive gases generated during mining. Although circular link chains require high strength, toughness, fatigue performance, and wear resistance, their failure mode is often not simply fatigue fracture or plastic deformation fracture, but rather sudden, deformation-free corrosive brittle fracture occurring well below their yield strength. Therefore, while ensuring comprehensive mechanical properties, special attention must be paid to the impact of corrosive environments on circular link chains.

[0004] Mining circular link chains are subjected to periodic tensile loads during service, with the stress distribution being most concentrated at the shoulder and top of the chain links. For high-strength steel, local stress concentration in a corrosive environment can easily lead to stress corrosion cracking. Once stress corrosion occurs, the cracks propagate rapidly in a short time, significantly reducing the service life of the material. Affected by underground corrosive media and wear, the surface of the circular link chain is damaged after a period of time: (1) pitting and other surface defects are generated, and the bottom of the pit forms a closed battery, causing a local pH value to decrease. If the conditions for cathodic hydrogen evolution reaction are met, the generated hydrogen atoms diffuse into the metal inside the crack tip; (2) after plastic deformation, the fresh metal without oxide film protection is re-exposed to the corrosive environment, and the local electrochemical action causes the metal to dissolve as an anode, and the crack tip continues to expand. These often become the precursors to stress corrosion cracking. For circular link chains, cracking occurs under the coupling effect of tensile load and corrosive media. Therefore, improving the stress corrosion resistance of mining circular link chains can effectively extend their service life underground. However, current research on invention patents for high-strength circular link chains for mining focuses on improving the corrosion resistance or overall wear and corrosion resistance of steel. There is very little research on the stress corrosion cracking resistance of circular link chains. Therefore, how to improve the stress corrosion resistance of circular link chains while ensuring high strength and high toughness has become an urgent problem to be solved. Summary of the Invention

[0005] In view of the above, the present invention aims to provide a high-strength mining circular link chain steel with stress corrosion resistance and its preparation method, in order to solve the problem that the strength, toughness and stress corrosion resistance of existing circular link chain steel cannot be effectively improved at the same time.

[0006] The objective of this invention is mainly achieved through the following technical solutions:

[0007] This invention provides a high-strength mining round link chain steel resistant to stress corrosion. The composition of the high-strength mining round link chain steel resistant to stress corrosion includes, by mass percentage: C: 0.22%–0.27%, Si: 0.10%–0.17%, Mn: 0.48%–0.62%, P: ≤0.015%, S: ≤0.005%, Cr: 0.41%–0.66%, Ni: 0.88%–1.23%, Mo: 0.41%–0.58%, Cu: 0.40%–0.60%, V: 0.18%–0.36%, W: 0.21%–0.45%, with the balance being Fe and unavoidable impurities.

[0008] Furthermore, the composition of the high-strength mining round link chain steel resistant to stress corrosion includes, by mass percentage: C: 0.22%–0.26%, Si: 0.10%–0.16%, Mn: 0.48%–0.61%, P: ≤0.015%, S: ≤0.005%, Cr: 0.41%–0.61%, Ni: 0.88%–1.20%, Mo: 0.41%–0.55%, Cu: 0.41%–0.60%, V: 0.18%–0.32%, W: 0.21%–0.42%, with the balance being Fe and unavoidable impurities.

[0009] Furthermore, the microstructure of high-strength mining circular link steel resistant to stress corrosion includes lath martensite and nanoscale precipitates.

[0010] Furthermore, in the microstructure of high-strength mining circular link chain steel resistant to stress corrosion, the nanoscale precipitates mainly include (V,Mo,W)C composite nanoscale precipitates.

[0011] Furthermore, the stress intensity factor K of high-strength mining round link chain steel resistant to stress corrosion cracking... ISCC ≥85MPa√m.

[0012] This invention also provides a method for preparing high-strength mining round link chain steel resistant to stress corrosion, the method comprising the following steps:

[0013] Step 1: Smelting and casting into billets;

[0014] Step 2: Roll the billet into a bar stock;

[0015] Step 3: Anneal and straighten the bar stock and then perform heat treatment to obtain high-strength mining round link chain steel resistant to stress corrosion. The heat treatment includes normalizing, quenching and tempering.

[0016] Furthermore, in step 3, the holding temperature for normalizing is 890–930℃.

[0017] Furthermore, in step 3, the quenching is carried out by heating the entire furnace to 860-890℃ and holding for 40-120 minutes.

[0018] Furthermore, in step 3, the quenching is performed using electromagnetic induction heating, heating the bar stock to 900-920℃, holding it at that temperature for 3-10 seconds, and then water cooling it to room temperature.

[0019] Furthermore, in step 3, the tempering holding temperature is 610–640℃.

[0020] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0021] The high-strength mining round link chain steel of the present invention, with its resistance to stress corrosion, achieves high strength, excellent toughness and plasticity, and superior resistance to stress corrosion by precisely controlling the content of elements such as C, Si, Ni, Mn, Cr, Mo, and Cu, and by adding vanadium and tungsten to improve the strength of the steel and refine the grain size.

[0022] The high-strength mining circular link chain steel of the present invention has a low content of expensive elements such as Mo, resulting in low cost.

[0023] The method for preparing high-strength mining circular link chain steel with stress corrosion resistance of the present invention adopts a normalizing + quenching + tempering process and precisely controls the parameters of each step to finally obtain a microstructure containing a large number of nano-sized precipitates. These fine precipitates act as strong hydrogen traps to effectively improve the steel's resistance to stress corrosion cracking and are very beneficial to improving the steel's comprehensive mechanical properties.

[0024] The method for preparing high-strength mining round link chain steel resistant to stress corrosion of the present invention utilizes electromagnetic induction heating to significantly shorten the holding time, combined with high-temperature tempering, to obtain high-strength mining round link chain steel with high strength, excellent toughness and plasticity, and superior resistance to stress corrosion. The preparation method of the present invention is simple and feasible, and has the prospect of large-scale application.

[0025] The high-strength mining round link chain steel of this invention exhibits high strength, good ductility and toughness, and excellent resistance to stress corrosion. Its yield strength is ≥1170MPa, tensile strength is ≥1210MPa, reduction of area is ≥60%, elongation after fracture is ≥14%, and room temperature impact toughness is A. kv2 High-strength mining round link chain steel with ≥100J, Vickers hardness ≥390HV, and resistance to stress corrosion cracking exhibits an ISCC (loss of elongation after fracture) ≤26.5% and an ISCC (loss of reduction of area) ≤41.5% in Walpole corrosion inhibitor (hydrochloric acid + sodium acetate + deionized water, pH approximately 3.7, room temperature). The stress intensity factor K for resistance to stress corrosion cracking is also high. ISCC ≥85MPa√m.

[0026] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of what is particularly pointed out in the written description and the accompanying drawings. Attached Figure Description

[0027] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0028] Figure 1 Here is a microscopic tissue SEM image from Example 1;

[0029] Figure 2 Here are the SEM images of the microstructure from Example 6;

[0030] Figure 3 TEM images of the matrix tissue in Example 1;

[0031] Figure 4 TEM image of the precipitated phase in Example 1;

[0032] Figure 5 The slow strain rate stretching curve of Example 1;

[0033] Figure 6 The crack propagation rate curve is shown for the wedge-opening loading (WOL) pre-cracked specimen of Example 1. Detailed Implementation

[0034] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of the present invention and, together with the embodiments of the present invention, serve to illustrate the principles of the present invention.

[0035] This invention provides a high-strength mining round link chain steel resistant to stress corrosion. The composition of the above-mentioned high-strength mining round link chain steel, by mass percentage, includes: C: 0.22%~0.27%, Si: 0.10%~0.17%, Mn: 0.48%~0.62%, P: ≤0.015%, S: ≤0.005%, Cr: 0.41%~0.66%, Ni: 0.88%~1.23%, Mo: 0.41%~0.58%, Cu: 0.40%~0.60%, V: 0.18%~0.36%, W: 0.21%~0.45%, with the balance being Fe and unavoidable impurities.

[0036] The following provides a detailed explanation of the function and dosage selection of the components contained in this invention.

[0037] Carbon: Carbon is the main element for increasing strength. Adding an appropriate amount of carbon can not only ensure the strength of steel, but also significantly improve its hardenability. However, the carbon content should not exceed 0.27%, otherwise the toughness and plasticity will be greatly reduced. Taking all factors into consideration, this invention controls the carbon content to be 0.22% to 0.27%.

[0038] Silicon: One of the deoxidizing elements in steel, and also a non-carbide-forming element, possesses strong solid solution strengthening properties. Silicon can effectively inhibit cementite precipitation, refine the size of cementite, and ensure its more uniform distribution, reducing carbon atom consumption. This allows the material to maintain high strength while mitigating temper brittleness. However, excessive Si will deteriorate the steel's toughness and weldability. Considering the above, the silicon content of the steel in this invention ranges from 0.10% to 0.17%.

[0039] Manganese: Manganese has a certain solid solution strengthening effect and can significantly improve the hardenability of steel. It has little impact on tempering stability and has a strong affinity for oxygen atoms, thus playing a deoxidizing role in the smelting process, which helps in subsequent desulfurization processes and improves the hot working performance of the material. However, the manganese content should not be too high, otherwise it may cause coarsening of steel grains and may also cause segregation within the material. The manganese content of the steel in this invention ranges from 0.48% to 0.62%.

[0040] Chromium: effectively improves the hardenability, corrosion resistance, oxidation resistance and wear resistance of steel, and can also effectively strengthen the matrix and improve the strength of materials. It forms a variety of carbides with carbon atoms. Its pinning effect can inhibit grain growth at the weld joint. However, a high Cr content is not good for welding performance. In this invention, it should be controlled at 0.41% to 0.66%.

[0041] Nickel: Nickel can improve the hardenability and corrosion resistance of steel, increase the density of the internal rust layer, ensure that the toughness does not decrease significantly after the strength is increased, and lower the brittle transition temperature of steel. However, its price is high. To ensure that the material itself has a certain degree of corrosion resistance, the content should be controlled between 0.88% and 1.23%.

[0042] Molybdenum (Mo) significantly improves the hardenability of steel, reduces temper brittleness, enhances impact toughness, strengthens grain boundary bonding, and improves the steel's resistance to delayed fracture. When added together with microalloying elements, Mo also improves the high-temperature dimensional stability of microalloyed precipitates and reduces their coarsening rate, which is beneficial for improving precipitation strengthening. However, excessive Mo content is not advisable, as its distribution on grain boundaries increases material brittleness, and it is also expensive. Therefore, the molybdenum content in the steel of this invention is controlled at 0.41%–0.58%.

[0043] Copper: Improves the hardenability and atmospheric corrosion resistance of steel, but copper-containing steel is prone to hot brittleness due to selective surface oxidation. Therefore, the copper content should be controlled within 0.40% to 0.60%.

[0044] Vanadium: The VC particles precipitated from the martensitic or ferrite matrix are finely dispersed and have a significant precipitation strengthening effect. Simultaneously, the formed VC particles can act as irreversible hydrogen traps to improve the steel's resistance to hydrogen embrittlement. In this invention, the V content in the steel is controlled between 0.18% and 0.36%. If the content is too high, the precipitation strengthening effect is not significantly improved, and the cost is also higher.

[0045] Tungsten: Similar to molybdenum, it increases tempering stability, improves hardenability and hardness, reduces the overheating sensitivity of steel, and can form carbides to enhance wear resistance. It also mitigates carbide aggregation during tempering at higher temperatures. This invention employs a design concept that substitutes molybdenum for tungsten, reducing material costs while ensuring the strength and toughness of the steel and increasing corrosion resistance and resistance to hydrogen embrittlement. The tungsten content in this invention is controlled at 0.21%–0.45%.

[0046] Phosphorus and sulfur: Impurity elements in steel that significantly reduce plasticity, toughness and weldability. Their contents should be controlled within 0.015% and 0.005% respectively.

[0047] Specifically, in order to further improve the overall performance of the aforementioned high-strength mining round link chain steel resistant to stress corrosion, the composition of the aforementioned high-strength mining round link chain steel resistant to stress corrosion includes, by mass percentage: C: 0.22%–0.26%, Si: 0.10%–0.16%, Mn: 0.48%–0.61%, P: ≤0.015%, S: ≤0.005%, Cr: 0.41%–0.61%, Ni: 0.88%–1.20%, Mo: 0.41%–0.55%, Cu: 0.41%–0.60%, V: 0.18%–0.32%, W: 0.21%–0.42%, with the balance being Fe and unavoidable impurities.

[0048] Specifically, the microstructure of the aforementioned high-strength mining circular link chain steel resistant to stress corrosion includes lath martensite and nanoscale precipitates.

[0049] Specifically, in the microstructure of the aforementioned high-strength mining circular link chain steel resistant to stress corrosion, the mass percentage of nanoscale precipitates is approximately 0.3% to 1%.

[0050] Specifically, in the microstructure of the aforementioned high-strength mining circular link chain steel with superior stress corrosion resistance, the nanoscale precipitates mainly include (V,Mo,W)C composite nanoscale precipitates.

[0051] Specifically, in the microstructure of the aforementioned high-strength mining circular link chain steel resistant to stress corrosion, the average lath spacing of the lath martensite is 120–200 nm.

[0052] Specifically, in the microstructure of the aforementioned high-strength mining circular link chain steel resistant to stress corrosion, the size of the nanoscale precipitates is approximately >0 to 25 nm.

[0053] On the other hand, the present invention also provides a method for preparing the above-mentioned high-strength mining round link chain steel resistant to stress corrosion, comprising the following steps:

[0054] Step 1: Smelting and casting into billets;

[0055] Step 2: Roll the billet into a bar stock;

[0056] Step 3: Anneal and straighten the bar stock and then perform heat treatment to obtain high-strength mining round link chain steel resistant to stress corrosion. The heat treatment includes normalizing, quenching and tempering.

[0057] Specifically, the steps of step 1 above include: preparing smelting raw materials according to chemical composition, raw material pretreatment, converter (or electric furnace) smelting, LF refining, RH refining, continuous casting, and slag removal and slow cooling after continuous casting to obtain billets.

[0058] Specifically, in step 3 above, the holding temperature for normalizing is controlled at 890–930℃, the holding time is 1–4 hours, and after being taken out of the furnace, it is air-cooled to room temperature.

[0059] Specifically, in step 3 above, quenching can be performed using a conventional heating furnace or electromagnetic induction heating. A conventional box-type high-temperature heat treatment furnace can be used.

[0060] Specifically, in step 3 above, quenching is performed using a traditional heating furnace. The specific steps include: placing the bar stock into the heating furnace, heating it to 860-890℃ and holding it for 40-120 minutes, and then water-cooling it to room temperature after removing it from the furnace.

[0061] Preferably, in step 3 above, the quenching is performed using electromagnetic induction heating. The specific steps include: heating the bar stock to 900-920°C using electromagnetic induction heating, holding it at that temperature for 3-10 seconds, and then water cooling it to room temperature.

[0062] Specifically, in step 3 above, considering that excessively high tempering holding temperatures would lead to severe softening of the matrix, making it difficult to maintain the required strength, while excessively low temperatures would result in precipitation behavior failing to meet thermodynamic requirements and thus reducing the quantity of precipitates; excessively long holding times would cause the precipitates to grow and coarsen, while excessively short holding times would prevent the precipitates from settling. Therefore, the tempering holding temperature is controlled at 610–640℃, the holding time at 1.5–3.5 h, and the precipitates are air-cooled to room temperature after being removed from the furnace.

[0063] Specifically, the aforementioned high-strength mining round link chain steel with stress corrosion resistance exhibits high strength, good ductility and toughness, and excellent resistance to stress corrosion. Its yield strength is ≥1170MPa, for example, 1173~1260MPa; tensile strength is ≥1210MPa, for example, 1213~1390MPa; reduction of area is ≥60%, for example, 62%~65%; elongation after fracture is ≥14%, for example, 14%~17%; and room temperature impact toughness A… kv2 ≥100J, e.g., 102~140J; Vickers hardness ≥390HV, e.g., 390~420HV. The stress corrosion cracking sensitivity (ISCC) of high-strength mining round link chain steel resistant to stress corrosion cracking in Walpole corrosion inhibitor (hydrochloric acid + sodium acetate + deionized water, pH approximately 3.7, room temperature) is ≤26.5%, e.g., 23%~26.2%; ISCC (reduction of area) ≤41.5%, e.g., 40%~41.3%; stress intensity factor K for stress corrosion cracking resistance. ISCC ≥85MPa√m, for example 87~93MPa√m.

[0064] The high-strength mining round link chain steel of the present invention, with its resistance to stress corrosion, achieves high strength, excellent toughness and plasticity, and superior resistance to stress corrosion by precisely controlling the content of elements such as C, Si, Ni, Mn, Cr, Mo, and Cu, and by adding vanadium and tungsten to improve the strength of the steel and refine the grain size.

[0065] The high-strength mining circular link chain steel of the present invention has a low content of expensive elements such as Mo, resulting in low cost.

[0066] The method for preparing high-strength mining circular link chain steel with stress corrosion resistance of the present invention adopts a normalizing + quenching + tempering process and precisely controls the parameters of each step to finally obtain a microstructure containing a large number of nano-sized precipitates. These fine precipitates act as strong hydrogen traps to effectively improve the steel's resistance to stress corrosion cracking and are very beneficial to improving the steel's comprehensive mechanical properties.

[0067] The method for preparing high-strength mining round link chain steel resistant to stress corrosion of the present invention utilizes electromagnetic induction heating to significantly shorten the holding time, combined with high-temperature tempering, to obtain high-strength mining round link chain steel with high strength, excellent toughness and plasticity, and superior resistance to stress corrosion. The preparation method of the present invention is simple and feasible, and has the prospect of large-scale application.

[0068] The high-strength mining round link chain steel of this invention exhibits high strength, good ductility and toughness, and excellent resistance to stress corrosion. Its yield strength is ≥1170MPa, tensile strength is ≥1210MPa, reduction of area is ≥60%, elongation after fracture is ≥14%, and room temperature impact toughness is A. kv2 High-strength mining round link chain steel with ≥100J, Vickers hardness ≥390HV, and resistance to stress corrosion cracking exhibits an ISCC (loss of elongation after fracture) ≤26.5% and an ISCC (loss of reduction of area) ≤41.5% in Walpole corrosion inhibitor (hydrochloric acid + sodium acetate + deionized water, pH approximately 3.7, room temperature). The stress intensity factor K for resistance to stress corrosion cracking is also high. ISCC ≥85MPa√m.

[0069] The advantages of precise control of the composition and process parameters of the steel of the present invention will be demonstrated below with specific embodiments and comparative examples.

[0070] Examples 1-7 of the present invention (referred to as A1-A7 in the table) provide a high-strength mining round link chain steel resistant to stress corrosion and its preparation method. The chemical composition of the steel in Examples 1-7 is shown in Table 1.

[0071] The methods for preparing the steel in Examples 1-5 include:

[0072] According to the above chemical composition, the smelting raw materials are pretreated, smelted in a converter, refined in LF, refined in RH and continuously cast into slabs. After slag removal and slow cooling, the continuously cast slabs are heated in a heating furnace and rolled into round bars with a diameter of 48mm. Then, they are annealed and straightened.

[0073] Cut the round bar wire into suitable lengths and place the whole section into a heating furnace for heat treatment: normalizing temperature 890~930℃, hold for 1~4h and then air cool; quenching temperature 860~890℃, hold for 40~120min and then water cool; tempering temperature 610~640℃, hold for 1.5~3h and then air cool.

[0074] The steel preparation methods in Examples 6-7 include:

[0075] According to the above chemical composition, the smelting raw materials are pretreated, smelted in a converter, refined in LF, refined in RH and continuously cast into slabs. After slag removal and slow cooling, the continuously cast slabs are heated in a heating furnace and rolled into round bars with a diameter of 48mm. Then, they are annealed and straightened.

[0076] Cut the round bar wire into suitable lengths and place the whole section into a heating furnace for normalizing treatment: normalizing temperature 890~930℃, hold for 1~4h and then air cool; electromagnetic induction heating quenching temperature 900~920℃, hold for 5s and then cool immediately; place the whole section into a heating furnace for tempering treatment: tempering temperature 610~640℃, hold for 1.5~3h and then air cool.

[0077] The specific process parameters for the heat treatment of Examples 1-7 are shown in Table 2; the microstructure of the high-strength mining round link chain steel resistant to stress corrosion is shown in Table 3; and the test results of the mechanical properties of the high-strength mining round link chain steel resistant to stress corrosion are shown in Table 4.

[0078] Figure 1 Here are the microscopic tissue SEM images from Example 1; Figure 2 Here are the SEM images of the microstructure from Example 6; Figure 3 TEM images of the matrix tissue in Example 1; Figure 4 TEM image of the precipitated phase in Example 1; Figure 5 The slow strain rate stretching curve of Example 1; Figure 6 The crack propagation rate curve is shown for the wedge-opening loading (WOL) pre-cracked specimen of Example 1.

[0079] The inventors conducted extensive experimental research during the research process, and some poorly performing solutions are now presented as comparative examples.

[0080] Comparative Example 1

[0081] This comparative example provides a steel for mining circular link chains and its preparation method. The composition is shown in Table 1, and the specific process parameters of the preparation method are shown in Table 2.

[0082] The composition of this comparative example is not within the scope of this application, and some process parameters of the preparation method do not meet the requirements. Therefore, the grain size in the microstructure of this comparative example is large, and the stress corrosion resistance is poor.

[0083] Comparative Example 2

[0084] This comparative example provides a steel for mining circular link chains and its preparation method. The composition is shown in Table 1, and the specific process parameters of the preparation method are shown in Table 2.

[0085] The composition of this comparative example is not within the scope of this application. The microstructure of this comparative example has a small number of nano-precipitates and poor resistance to stress corrosion.

[0086] Comparative Example 3

[0087] This comparative example provides a steel for mining circular link chains and its preparation method. The composition is shown in Table 1, and the specific process parameters of the preparation method are shown in Table 2.

[0088] The composition of this comparative example is not within the scope of this application. The precipitated phase in the microstructure of this comparative example is large in size and has poor resistance to stress corrosion.

[0089] The steel used for the circular link chains in the embodiments and comparative examples (B1-B3) of the present invention were all prepared into samples that met the requirements of national standards after heat treatment for testing.

[0090] The steel used for the circular link chains in the embodiments and comparative examples of this invention underwent slow strain rate tensile tests and wedge-open loading (WOL) pre-cracked specimen stress corrosion tests according to the requirements of GB / T15970 and GB / T12445 standards. Test samples were prepared according to the standard requirements. The slow strain rate tensile test environment was compared between air and Walpole corrosion inhibitor (hydrochloric acid + sodium acetate + deionized water, pH approximately 3.7, room temperature), with a tensile rate of 1×10⁻⁶. -6 s -1 The specimen surface was smooth. Changes in the length and necking diameter of the specimen before and after fracture were measured to calculate the elongation A and reduction of area Z. After the test, the stress corrosion susceptibility index was calculated using the formula ISCC = (Ia - Is) / Ia, where Ia is the experimental parameter in air and Is is the experimental parameter in Walpole corrosion inhibitor. The stress corrosion test environment for the wedge-shaped opening loading (WOL) pre-cracked specimens was Walpole corrosion inhibitor (hydrochloric acid + sodium acetate + deionized water, pH approximately 3.7, temperature 35±0.5℃). The stress intensity factor was calculated based on the measured crack length and other relevant parameters, following the specific calculation method specified in GB / T12445 standard.

[0091] Table 1 Chemical composition, wt%

[0092]

[0093]

[0094] Table 2 Specific Process Parameters

[0095]

[0096] Table 3 Microstructure of Steel

[0097]

[0098]

[0099] Table 4 Mechanical Properties of Steel

[0100]

[0101] Table 5 Results of slow strain rate tensile tests and wedge-opening loading (WOL) pre-cracked specimen stress corrosion tests

[0102]

[0103]

[0104] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-strength steel for mining circular link chains resistant to stress corrosion, characterized in that, The high-strength mining round link chain steel with stress corrosion resistance comprises, by mass percentage: C: 0.22%–0.27%, Si: 0.10%–0.17%, Mn: 0.48%–0.62%, P: ≤0.015%, S: ≤0.005%, Cr: 0.41%–0.53%, Ni: 0.88%–1.23%, Mo: 0.41%–0.58%, Cu: 0.40%–0.60%, V: 0.18%–0.36%, W: 0.21%–0.45%, with the balance being Fe and unavoidable impurities; The microstructure of the high-strength mining circular link chain steel with stress corrosion resistance includes lath martensite and nanoscale precipitates; the nanoscale precipitates mainly include (V,Mo,W)C composite nanoscale precipitates; the mass percentage of nanoscale precipitates is about 0.3%~1%, and the average lath spacing of the lath martensite is 120~200nm. The high-strength mining round link chain steel with stress corrosion resistance has a yield strength ≥1170MPa, tensile strength ≥1210MPa, reduction of area ≥60%, elongation after fracture ≥14%, and room temperature impact toughness A. kv2 ≥100J, stress intensity factor K for resistance to stress corrosion cracking ISCC ≥85 MPa√m.

2. The high-strength mining round link chain steel resistant to stress corrosion according to claim 1, characterized in that, The high-strength mining round link chain steel with stress corrosion resistance comprises, by mass percentage: C: 0.22%–0.26%, Si: 0.10%–0.16%, Mn: 0.48%–0.61%, P: ≤0.015%, S: ≤0.005%, Cr: 0.41%–0.53%, Ni: 0.88%–1.20%, Mo: 0.41%–0.55%, Cu: 0.41%–0.60%, V: 0.18%–0.32%, W: 0.21%–0.42%, with the balance being Fe and unavoidable impurities.

3. The high-strength mining round link chain steel resistant to stress corrosion according to claim 1, characterized in that, The stress intensity factor K of the high-strength mining round link chain steel resistant to stress corrosion cracking ISCC It is 87~93 MPa√m.

4. A method for preparing high-strength mining circular link chain steel resistant to stress corrosion, characterized in that, The preparation method is used to prepare the high-strength mining round link chain steel with stress corrosion resistance as described in any one of claims 1 to 3, and the preparation method includes the following steps: Step 1: Smelting and casting into billets; Step 2: Roll the billet into a bar stock; Step 3: Anneal and straighten the bar stock and then perform heat treatment to obtain high-strength mining round link chain steel resistant to stress corrosion. The heat treatment includes normalizing, quenching and tempering.

5. The preparation method according to claim 4, characterized in that, In step 3, the holding temperature for normalizing is 890–930°C.

6. The preparation method according to claim 4, characterized in that, In step 3, the quenching is carried out by heating the entire furnace, raising the temperature to 860-890℃ and holding it for 40-120 minutes.

7. The preparation method according to claim 4, characterized in that, In step 3, quenching is performed using electromagnetic induction heating, heating the bar stock to 900-920°C, holding it at that temperature for 3-10 seconds, and then water cooling it to room temperature.

8. The preparation method according to any one of claims 4 to 7, characterized in that, In step 3, the tempering holding temperature is 610–640°C.

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