High abrasion resistant martensitic stainless steel, method for manufacturing and use thereof

Abstract

The application discloses a kind of high abrasion-resistant martensitic stainless steel and its preparation method and application, belong to metal material technical field.Its chemical composition is as follows according to percentage by mass: C 0.60%~0.70%, N 0.10%~0.20%, Cr 15.0%~17.0%, Mo 0.8%~1.2%, Si 0.5%~0.9%, Mn 0.3%~0.6%, V 0.2%~0.5%, the rest is Fe and unavoidable impurities, wherein the total content of impurities phosphorus and sulfur is not more than 0.03%.Preparation method adopts the innovation heat treatment system of multistage quenching, deep cold and low temperature compound tempering.The application realizes the balance between high hardness, high strength and excellent abrasion resistance of steel through component design and heat treatment system optimization, is suitable for deep sea equipment long-term service, has remarkable engineering application prospect and economic benefit.

Description

Technical Field

[0001] This invention relates to the field of metallic materials technology, specifically to a highly wear-resistant martensitic stainless steel, its preparation method, and its applications. Background Technology

[0002] The extreme and complex nature of the ocean, especially the deep-sea environment, places near-stringent demands on engineering materials used in its service. Key components of deep-sea equipment, such as drilling system hoists, valves, mud pump flow parts, and the articulation mechanisms and thrusters of underwater robots, not only endure hydrostatic pressures of hundreds of atmospheres for extended periods but are also continuously exposed to low-temperature seawater rich in chloride ions. Even more challenging is the fact that these components often simultaneously experience erosion and abrasive wear caused by water flow, sediment, and suspended particles. This accelerated destructive effect caused by the synergistic effect of wear and corrosion is known as "abrasion," and its failure rate is far higher than the cumulative effect of wear or corrosion alone. Therefore, developing highly abrasion-resistant steels that combine high strength, high hardness, and excellent seawater corrosion resistance has become a key scientific and engineering challenge in the field of marine engineering materials, especially in deep-sea technology and equipment.

[0003] Currently, the main metallic materials used in marine environments include titanium alloys, stainless steel, and high-carbon tool steel. Titanium and its alloys possess excellent resistance to seawater corrosion, but their high cost, poor wear resistance, and difficult processing make them unsuitable for large-sized components or those subjected to strong impacts. While polymers and composite materials offer corrosion resistance, their mechanical strength and temperature resistance are far lower than metals, making them unsuitable for high-load components in deep seas. Austenitic stainless steels (such as 316L) and duplex stainless steels perform well in corrosion resistance, but their inherent low hardness and strength result in severely insufficient wear resistance. High-carbon, high-chromium tool steels or bearing steels, while possessing high hardness, suffer from "chromium-depleted zones" around carbides due to their high carbon content, making them highly susceptible to pitting corrosion and even perforation failure in chlorinated environments. This series of comparisons demonstrates that currently, no metallic material can simultaneously achieve both high hardness and high corrosion resistance, enabling long-term adaptation to the complex working conditions of the deep sea.

[0004] Therefore, the core technological bottleneck that has long been faced in this field is the lack of innovative and feasible high wear-resistant and corrosion-resistant martensitic stainless steel for deep-sea applications in terms of composition design, microstructure control and process feasibility. It is difficult to achieve high strength, high hardness and excellent seawater corrosion resistance at the same time, and it is impossible to achieve synergistic optimization of wear resistance and corrosion resistance. Summary of the Invention

[0005] To address the issue that existing deep-sea high-wear-resistant steels cannot simultaneously achieve high hardness, high strength, excellent seawater corrosion resistance, and wear resistance, this invention provides a high-wear-resistant martensitic stainless steel, its preparation method, and its applications.

[0006] In a first aspect, the present invention provides a highly wear-resistant martensitic stainless steel, the chemical composition of which, by mass percentage, comprises the following elements: C 0.60%~0.70%, N 0.10%~0.20%, Cr 15.0%~17.0%, Mo 0.8%~1.2%, Si 0.5%~0.9%, Mn 0.3%~0.6%, V 0.2%~0.5%, with the remainder being Fe and unavoidable impurity elements, wherein the total content of the impurity elements phosphorus and sulfur is not greater than 0.03%.

[0007] Furthermore, the highly wear-resistant martensitic stainless steel has a hardness > 59 HRC, tensile strength > 2000 MPa, yield strength > 1850 MPa, elongation > 5%, pitting potential > 0 mV vs SCE, and corrosion current density under static pure corrosion conditions < 7 × 10⁻⁶ mV. -7 A / cm 2 The wear rate during the abrasion process is reduced by more than 15% compared to 316L stainless steel.

[0008] Preferably, the chemical composition of the high wear-resistant martensitic stainless steel is composed of the following elements by mass percentage: C 0.64%~0.67%, N 0.15%~0.18%, Cr 16.3%~16.7%, Mo 0.9%~1.1%, Si 0.6%~0.8%, Mn 0.35%~0.45%, V 0.3%~0.4%, with the remainder being Fe and unavoidable impurity elements.

[0009] Furthermore, the highly wear-resistant martensitic stainless steel has a hardness > 59.5 HRC, tensile strength > 2100 MPa, yield strength > 1900 MPa, elongation > 5%, pitting potential > 10 mV vs SCE, and corrosion current density under static pure corrosion conditions < 5 × 10⁻⁶ mV. -7 A / cm 2 The wear rate during the abrasion process is reduced by more than 20% compared to 316L stainless steel.

[0010] A second aspect of the present invention provides a method for preparing highly wear-resistant martensitic stainless steel, comprising the following steps: S1 Smelting and casting: Take the alloying elements according to the chemical composition of any one of claims 1-4, smelt them, and cast them into alloy ingots; S2 Homogenization and Forging: The alloy ingot is subjected to solution treatment, followed by hot forging in the austenitic single-phase region; S3 multi-stage quenching treatment: The forging is heated and held in a stepped temperature range of 620℃~1060℃, and then cooled. S4 cryogenic treatment: Deep cryogenic treatment is performed after quenching; S5 Low-Temperature Composite Tempering: After cryogenic treatment, medium-temperature tempering and low-temperature tempering are performed sequentially.

[0011] Furthermore, in step S1, the remelting is carried out at least three times in a vacuum arc melting furnace; in step S2, the solution treatment temperature is 1150℃±10℃, the solution treatment time is 10~14 hours, the forging ratio is 8~9, and the final forging temperature is controlled within the range of 900℃~950℃.

[0012] Further, in step S3, the forgings are held at temperatures of 630℃±10℃, 850℃±10℃ and 1050℃±10℃ for 10~20 minutes each, and then oil-cooled.

[0013] Furthermore, in step S4, the cryogenic treatment is carried out in liquid nitrogen for a holding time of 1 to 8 hours.

[0014] Further, in step S5, the medium-temperature tempering is held at 500℃±10℃ for 1.5~2.5 hours; the low-temperature tempering is held at 125℃~180℃ for 0.5~1.5 hours.

[0015] A third aspect of the present invention provides the application of the above-described high wear-resistant martensitic stainless steel in deep-sea equipment.

[0016] Compared with the prior art, the present invention has at least the following beneficial effects: This invention is based on the design concept of C+N synergistic strengthening and V carbide dispersion strengthening. While maintaining high hardness, it effectively suppresses the formation of chromium-depleted zones caused by carbide precipitation in traditional high-carbon martensitic steel, thus achieving a balance between high strength, high hardness, and excellent seawater corrosion resistance, and realizing synergistic optimization of wear resistance and corrosion resistance. The preparation method adopts an innovative heat treatment system of multi-stage quenching, deep cryogenic treatment, and medium-low temperature composite tempering, which refines carbide dispersion, stabilizes the content of retained austenite, and improves the uniformity of the microstructure, thereby obtaining excellent mechanical-corrosion synergistic properties. Moreover, the preparation process parameters are all within the range achievable by conventional heat treatment equipment, making the process controllable, cost-effective, and possessing good industrial feasibility and promotional value. The high wear-resistant martensitic stainless steel of this invention exhibits excellent wear resistance and electrochemical stability in simulated deep-sea environments with high pressure, high chlorine, and particulate matter. It is suitable for long-term service in deep-sea equipment and can be widely used in key components such as deep-sea drilling and production equipment, seabed valve bodies, mud pump flow parts, underwater robot drive mechanisms, propeller shafts, and shearing cutters. It has significant engineering application prospects and economic benefits. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments recorded in the embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0018] Figure 1 This is a micrograph of the highly wear-resistant martensitic stainless steel in Example 1 of the present invention; Figure 2 The polarization curves of the high wear-resistant martensitic stainless steel and 316L in artificial seawater in Example 1 of this invention are shown. Figure 3 The images show the surface wear marks of the high wear-resistant martensitic stainless steel and other steels in artificial seawater after abrasion in Example 1 of the present invention; wherein, (a) 316L stainless steel, (b) M35, (c) GCr15, and (d) the high wear-resistant martensitic stainless steel of Example 1. Detailed Implementation

[0019] To better understand the above technical solutions, the technical solutions of the embodiments of this application will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments of this application and the specific features in the embodiments are detailed descriptions of the technical solutions of the embodiments of this application, rather than limitations on the technical solutions of this application. In the absence of conflict, the embodiments of this application and the technical features in the embodiments can be combined with each other.

[0020] In a first aspect, this invention provides a highly wear-resistant martensitic stainless steel, the chemical composition of which, by mass percentage, consists of the following elements: C 0.60%~0.70%, N 0.10%~0.20%, Cr 15.0%~17.0%, Mo 0.8%~1.2%, Si 0.5%~0.9%, Mn 0.3%~0.6%, V 0.2%~0.5%, with the remainder being Fe and unavoidable impurity elements, wherein the total content of the impurity elements phosphorus and sulfur is not greater than 0.03%.

[0021] The high wear-resistant martensitic stainless steel provided in this invention has a chemical composition design based on extensive experimental evaluation and performance optimization results. Through the synergistic effect of multiple strengthening mechanisms, it achieves a balance between high hardness, high strength and excellent wear resistance.

[0022] Carbon, as a fundamental element for martensitic strength formation, is controlled within a medium-to-high content range of 0.60% to 0.70%. This significantly improves the material's hardness and strength through solid solution strengthening and carbide precipitation strengthening, while avoiding the formation of continuous chromium-depleted zones and network carbides due to excessive carbon content, thus ensuring corrosion resistance. Nitrogen forms stable carbonitride phases in the presence of chromium and produces a significant solid solution strengthening effect. Its content is controlled within the range of 0.10% to 0.20%, effectively inhibiting the formation of chromium-depleted bands at grain boundaries, improving the stability of the passivation film, significantly enhancing the material's resistance to pitting corrosion in chloride-containing media, and improving microstructural stability. Chromium and molybdenum are key alloying elements for improving the corrosion resistance of the steel of this invention. Chromium can form a dense and stable passivation film on the steel surface, giving the material basic stainless properties; molybdenum can significantly enhance the passivation film's resistance to chloride ion damage, improving resistance to pitting and crevice corrosion in high-chlorine environments such as seawater. This invention controls the chromium content to 15.0%~17.0% and the molybdenum content to 0.8%~1.2%, ensuring corrosion resistance while also considering structural stability and processing performance. Vanadium in this invention primarily exerts a secondary hardening effect by forming dispersed, fine VC carbides, effectively improving the material's hardness and wear resistance, and inhibiting carbide coarsening. Silicon and manganese are mainly used to improve deoxidation during the smelting process and hot working performance, while also providing some solid solution strengthening, which is beneficial for obtaining a uniform and dense microstructure.

[0023] The high-wear-resistant martensitic stainless steel of this invention adopts a design concept of C+N synergistic strengthening and V carbide dispersion strengthening. While maintaining high hardness, it improves corrosion resistance and avoids the chromium-depleted zone failure problem of traditional high-carbon martensitic steel. This results in a high-wear-resistant martensitic stainless steel with a hardness >59 HRC, tensile strength >2000 MPa, yield strength >1850 MPa, elongation >5%, pitting potential >0 mV vs SCE; and corrosion current density <7×10⁻⁶ mV under static pure corrosion conditions. -7 A / cm 2 The wear rate during the abrasion process is reduced by more than 15% compared to 316L stainless steel, and the wear marks are shallow, fine and smooth, the passivation film is complete and dense, and it can quickly recover to the passivation state after the film is removed.

[0024] Preferably, the chemical composition of the high-wear-resistant martensitic stainless steel, by mass percentage, consists of the following elements: C 0.64%~0.67%, N 0.15%~0.18%, Cr 16.3%~16.7%, Mo 0.9%~1.1%, Si 0.6%~0.8%, Mn 0.35%~0.45%, V 0.3%~0.4%, with the remainder being Fe and unavoidable impurity elements, wherein the total content of the impurity elements phosphorus and sulfur is not greater than 0.03%. After optimizing the chemical composition, the resulting high-wear-resistant martensitic stainless steel exhibits a hardness > 59.5 HRC, tensile strength > 2100 MPa, yield strength > 1900 MPa, elongation > 5%, pitting potential > 10 mV vs SCE; and corrosion current density under static pure corrosion conditions < 5 × 10⁻⁶ mV. -7 A / cm 2 The wear rate during the abrasion process is reduced by more than 20% compared to 316L stainless steel, and the wear marks are shallow, fine and smooth, the passivation film is complete and dense, and it can quickly recover to the passive state after the film is removed.

[0025] A second aspect of this invention provides a method for preparing highly wear-resistant martensitic stainless steel, comprising the following steps: S1. Smelting and casting: Take the alloying elements according to the above chemical composition, smelt them, and cast them into alloy ingots; S2. Homogenization and forging: The alloy ingot is subjected to solution treatment, followed by hot forging in the austenitic single-phase region; S3. Multi-stage quenching treatment: The forging is heated and held in a stepped manner within the temperature range of 620℃~1060℃, and then cooled. S4. Cryogenic treatment: Deep cryogenic treatment is performed after quenching. S5, Medium and low temperature combined tempering: After cryogenic treatment, medium temperature tempering and low temperature tempering are performed in sequence.

[0026] This invention utilizes a compositional design approach combining C-N synergistic strengthening and V carbide dispersion strengthening, along with a heat treatment process involving multi-stage quenching, deep cryogenic treatment, and medium-low temperature composite tempering. This significantly improves seawater corrosion resistance and abrasion resistance while achieving high hardness and strength, effectively avoiding the grain boundary chromium-depleted regions and continuous network carbides commonly found in traditional high-carbon martensitic stainless steels. The material exhibits excellent mechanical-corrosion synergistic properties in high-pressure, high-chlorine, and particulate abrasion environments. Furthermore, the manufacturing process parameters are all within the achievable range of existing industrial equipment, demonstrating good process controllability and promising prospects for industrial applications. It is particularly suitable for critical engineering components such as deep-sea drilling and production equipment, subsea valve bodies, mud pump flow parts, and underwater robot transmission and connection components.

[0027] In some embodiments, in step S1, the remelting process is carried out at least three times in a vacuum arc melting furnace.

[0028] Specifically, the raw materials are first weighed according to the chemical composition ratio, and then remelted at least three times in a vacuum arc melting furnace to ensure uniform distribution of alloying elements and avoid segregation. During the melting process, the arc energy and melting time are strictly controlled to prevent element burn-off, and then the material is cast into steel ingots.

[0029] In some embodiments, in step S2, the solution treatment temperature is 1150℃±10℃, the solution treatment time is 10~14 hours, the hot forging ratio is 8~9, and the final forging temperature is controlled within the range of 900℃~950℃.

[0030] Specifically, the steel ingot is subjected to homogenization solution treatment at 1150℃±10℃ to eliminate as-cast segregation and homogenize the microstructure. Then, it is hot-forged in the austenitic single-phase region, with the forging ratio controlled at 8~9 and the final forging temperature controlled within the range of 900℃~950℃, to obtain a dense and uniform as-forged microstructure. During the forging process, the deformation rate and total deformation are strictly controlled to avoid cracking.

[0031] In some embodiments, in step S3, the forgings are held at temperatures of 630℃±10℃, 850℃±10℃ and 1050℃±10℃ for 10~20 minutes at each temperature, and then oil-cooled.

[0032] Specifically, in the heat treatment stage, the forged material is subjected to multi-stage quenching at temperatures of 630℃±10℃, 850℃±10℃ and 1050℃±10℃ for 10~20 minutes respectively, followed by oil cooling. The multi-stage quenching process promotes the full dissolution of carbides, refines the original austenite grains, and obtains a uniform martensitic matrix structure.

[0033] In some embodiments, in step S4, the cryogenic treatment is carried out in liquid nitrogen for a holding time of 1 to 8 hours, preferably 4 to 6 hours.

[0034] Specifically, the quenched material is then subjected to cryogenic treatment in liquid nitrogen (-196°C) to promote the further transformation of retained austenite into martensite, thereby improving the microstructure and dimensional stability. For martensitic stainless steel, a holding time of 4-6 hours is a beneficial window, at which point the retained austenite is fully transformed and carbides are dispersedly precipitated, achieving the best overall balance of strength, wear resistance, and toughness. Below 4 hours, the transformation is incomplete, with a large amount of retained austenite remaining, resulting in insufficient improvement in microstructure stability and hardness. Above 6 hours, although retained austenite can be further reduced and strength increased, impact toughness decreases significantly, and the performance gains tend to saturate.

[0035] In some embodiments, in step S5, the medium-temperature tempering is held at 500℃±10℃ for 1.5~2.5 hours, and the low-temperature tempering is held at 125℃~180℃ for 0.5~1.5 hours.

[0036] Specifically, after cryogenic treatment, the material is first subjected to medium-temperature tempering, followed by low-temperature tempering. The medium-temperature tempering is used to promote the growth of VC and M. 23 The dispersed precipitation of C6 carbides achieves a significant secondary hardening effect; low-temperature tempering is used to release internal stress and stabilize a small amount of residual austenite, further improving the stability of the microstructure and properties.

[0037] A third aspect of the present invention provides the application of the above-mentioned high wear-resistant martensitic stainless steel in deep-sea equipment, which is particularly suitable for key engineering components such as deep-sea drilling and production equipment, seabed valve bodies, mud pump flow parts, and underwater robot transmission and connection components.

[0038] Example 1: Highly wear-resistant martensitic stainless steel and its preparation method (a) High wear-resistant martensitic stainless steel (60C) This embodiment provides a typical high-wear-resistant martensitic stainless steel with the following chemical composition (mass percentage): C 0.60%, N 0.15%, Cr 16.5%, Mo 1.0%, Si 0.7%, Mn 0.4%, V 0.35%, Fe balance, and total impurities (P, S) ≤0.03%. This composition design is based on the C-N synergistic strengthening principle: C provides the basis for carbide precipitation strengthening, N enhances solid solution strength and inhibits the formation of chromium-depleted bands, Cr and Mo ensure the stability of the passivation film, and V promotes the formation of fine VC particles, achieving a balance between high hardness and corrosion resistance.

[0039] (II) Preparation method Includes the following steps: (1) Smelting and casting Each alloying element is accurately weighed according to the proportion, and the mixture is remelted at least three times in a vacuum arc melting furnace to ensure uniform composition, and finally cast into a 20 kg cylindrical steel ingot.

[0040] (2) Homogenization and forging The ingot was solution treated at 1150℃±10℃ for 12 hours and then air-cooled. It was then hot-forged in the austenitic single-phase region (1100~900℃) with a forging ratio controlled at 8~9 to obtain a slab with a cross section of 50 mm×100 mm.

[0041] (3) Multi-stage quenching The forgings were held at 630℃, 850℃ and 1050℃ for 15 min each, and then oil-cooled to achieve full dissolution of carbides, refinement of the original austenite grains and improvement of microstructure uniformity.

[0042] (4) Cryogenic treatment Immediately after quenching, the sample is placed in liquid nitrogen (-196℃) for 4 hours to promote the complete transformation of residual austenite to martensite, improve dimensional stability, and refine the lath structure.

[0043] (5) Low-temperature composite tempering First, heat at 500℃ for 2 hours (medium-temperature tempering) to promote the production of VC and M. 23 C6 is dispersed and precipitated, and then subjected to low-temperature tempering at 150℃ for 1 hour to stabilize a small amount of residual austenite and release internal stress.

[0044] (III) Microstructural characterization and performance testing Metallographic and transmission electron microscopy analysis revealed that the microstructure of the steel consisted of refined lath martensite plus diffusely distributed M... 23 C6 and VC carbides + approximately 12% retained austenite. The carbides are mainly distributed as submicron (0.1~0.8 μm) spherical or dispersed particles within the grain boundaries and martensite laths; no continuous network of chromium-depleted regions were observed. Figure 1 As shown.

[0045] Performance test results show that the steel has a hardness of 59.8 HRC, a tensile strength of 2185 MPa, a yield strength of approximately 1910 MPa, and an elongation of 6.5%. Potentiodynamic polarization testing in artificial seawater showed a pitting potential of approximately +47 mV (vs SCE), and a corrosion current density of 4.64 × 10⁻⁶ mV for the static pure corrosion process. -7 A / cm 2 It is significantly superior to traditional 440C steel, and its corrosion resistance is comparable to 316L stainless steel. Figure 2 As shown in Table 1, abrasion tests were conducted in artificial seawater using a simulated deep-sea high-pressure corrosion and wear device according to the ASTM G99-05 standard. The results compared 316L stainless steel, M35 tool steel, and GCr15 bearing steel. Figure 3 Photographs of surface wear marks on the highly wear-resistant martensitic stainless steel and other steels from Example 1 after abrasion in artificial seawater are shown. Under static pure corrosion conditions, the corrosion current density of the steel of this invention is 4.64 × 10⁻⁶. -7 A / cm 2 It is comparable to 316L and significantly better than M35 (1.60×10). -6 A / cm 2 ) and GCr15 (2.85×10 -6 A / cm 2 It exhibits excellent resistance to seawater corrosion. During the erosion process, the corrosion voltage of Example 1 shifted negatively by 0.27 V, which is greater than that of the comparative material, indicating that the passivation film is intact and dense, and normal rupture and repassivation occur under mechanical action. Its wear rate is 40.0 mm / y, which is comparable to GCr15 and better than 316L (47.8 mm / y); combined with the wear track morphology ( Figure 3 The steel of this invention exhibits shallow, fine, and smooth wear marks, while M35 shows spalling pits, and GCr15 has dense furrows. This demonstrates that the high-wear-resistant martensitic stainless steel of this invention, while achieving high hardness and strength, significantly improves pitting corrosion resistance and wear resistance, proving the rationality of the composition design and heat treatment path.

[0046] Table 1. Comparison of electrochemical properties and wear rates of 316L, M35, GCr15 and the steel of this invention in artificial seawater.

[0047] Example 2: Comparison of Heat Treatment Procedures To verify the effect of heat treatment regime on the comprehensive properties of the steel of the present invention, the high wear-resistant martensitic stainless steel of Example 1 was selected, and three different heat treatment routes were used for comparison. The remaining preparation steps were the same as those of Example 1. The comparison results are shown in Table 2.

[0048] Option A (conventional heat treatment): Quenching at 1050℃ + tempering at 200℃ for 2 hours; Option B (Cryogenic Composite): 1050℃ quenching + liquid nitrogen cryogenic (-196℃, 4 hours) + 200℃ tempering for 2 hours; Scheme C (process of Example 1): multi-stage quenching (630℃+850℃+1050℃) + deep cryogenic (-196℃, 4 hours) + medium temperature tempering (500℃×2 hours) + low temperature tempering (150℃×1 hour).

[0049] Table 2 Properties of high wear-resistant martensitic stainless steel with different heat treatment schemes

[0050] As shown in Table 2, the multi-stage quenching + deep cryogenic + medium-low temperature composite tempering process (Scheme C) proposed in Example 1 of this invention is significantly superior to conventional schemes in terms of hardness and strength, while having the lowest residual austenite content and the most stable microstructure. Electrochemical testing shows that the pitting potential of Scheme C is +47 mV, which, although lower than Scheme A (+120 mV) and Scheme B (+75 mV), still remains at a high level (>30 mV), indicating that the material still has good passivation film stability. Meanwhile, the wear loss volume of Scheme C (2.13 × 10⁻⁶ mV) is also significantly lower. 7 μm 3 The reduction of 25.3% compared to scheme A and 16.8% compared to scheme B indicates that its excellent wear and corrosion resistance mainly stems from increased hardness, refined microstructure, and carbide dispersion reinforcement, rather than simply relying on improved corrosion resistance.

[0051] Example 3 Comparison of alloy composition To further evaluate the effect of the content of key elements such as C, N, and V in the alloy system of this invention on the comprehensive mechanical properties and corrosion resistance, the content of each single element was adjusted based on Example 1 to design the following three alloy compositions, all of which were prepared using the preparation method described in Example 1.

[0052] The three test components are as follows: Option 1: C-0.65% (increase C content) C 0.65%, N 0.15%, Cr 16.5%, Mo 1.0%, Si 0.7%, Mn 0.4%, V 0.35%, Fe balance.

[0053] Option 2: N - 0.20% (increase N content) C 0.60%, N 0.20%, Cr 16.5%, Mo 1.0%, Si 0.7%, Mn 0.4%, V 0.35%, Fe balance.

[0054] Option 3: V-0.45% (increase V content) C 0.60%, N 0.15%, Cr 16.5%, Mo 1.0%, Si 0.7%, Mn 0.4%, V 0.45%, Fe balance.

[0055] Table 3. Properties of high wear-resistant martensitic stainless steel prepared by the method in Example 1 with different composition schemes.

[0056] Example 3 systematically evaluated the effects of key elements on the mechanical properties and corrosion resistance of the martensitic stainless steel of this invention by changing the C, N, and V contents. As shown in Table 3, increasing the C content to 0.65% (Scheme 1: C-0.65%) improves hardness and tensile strength. This is because the higher carbon content promotes martensitic solid solution strengthening and more complete precipitation of carbides after quenching. However, this scheme slightly reduces elongation and pitting potential to +15 mV, indicating an increased tendency for excessive C segregation and localized chromium depletion at grain boundaries, leading to a decrease in corrosion resistance. Increasing the nitrogen content to 0.20% (Scheme 2: N-0.20%) maintains high strength while improving elongation and pitting potential. This is because N has strong strengthening solid solution and nitride formation capabilities, effectively suppressing chromium-depleted grain boundary regions and improving the stability of the passivation film. Increasing the V content to 0.45% (Scheme 3: V-0.45%) results in a stronger secondary hardening effect, improving both hardness and strength. Simultaneously, due to the enhanced wear resistance caused by VC precipitation, its mechanical properties fall between those of high-C and high-N steels. Overall, Scheme 2 (high N) achieves the best balance between strength, plasticity, and corrosion resistance, with the highest pitting potential (+62 mV) and the largest elongation (6.8%). Scheme 3 (high V) exhibits the highest yield strength (2045 MPa), making it suitable for scenarios dominated by high-stress abrasion. These results further validate the effectiveness and scalability of the composition design in this invention for performance control.

[0057] Comparative Example 1 This comparative example uses the same preparation method as Example 1, the only difference being that the C content in the alloy composition is 0.85% (exceeding the range of 0.60%~0.70% of this invention), and the other components are the same as in Example 1.

[0058] Performance test results show that the comparative steel has a hardness of 60.5 HRC and a tensile strength of 2220 MPa, but its elongation is only 3.2%, it has no passivation range, and its corrosion current density under static pure corrosion conditions is 2.98 × 10⁻⁶. -6 A / cm 2 The wear rate during the abrasion process was 67.1 mm / y. Microscopic observation revealed continuous network carbides at the grain boundaries and obvious chromium-depleted areas. The results indicate that although excessive carbon content can further improve hardness and strength, it leads to a sharp decline in corrosion resistance, failing to meet the basic requirements for seawater corrosion resistance in deep-sea environments. This verifies the necessity of controlling the C content within the range of 0.60% to 0.70% in this invention.

[0059] It will be readily understood by those skilled in the art that the above-described advantageous methods can be freely combined and superimposed without conflict. The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application. The above are merely preferred embodiments of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this application, and these improvements and modifications should also be considered within the protection scope of this application.

Claims

1. A highly wear-resistant and corrosion-resistant martensitic stainless steel, characterized in that, Its chemical composition, by mass percentage, consists of the following elements: C 0.60%~0.70%, N 0.10%~0.20%, Cr 15.0%~17.0%, Mo 0.8%~1.2%, Si 0.5%~0.9%, Mn 0.3%~0.6%, V 0.2%~0.5%, with the remainder being Fe and unavoidable impurity elements, of which the total content of impurity elements phosphorus and sulfur is no more than 0.03%.

2. The high wear-resistant and corrosion-resistant martensitic stainless steel according to claim 1, characterized in that, The high-wear-resistant martensitic stainless steel has a hardness > 59 HRC, tensile strength > 2000 MPa, yield strength > 1850 MPa, elongation > 5%, pitting potential > 0 mV vs SCE, and corrosion current density under static pure corrosion conditions < 7 × 10⁻⁶ mV. -7 A / cm 2 The wear rate during the abrasion process is reduced by more than 15% compared to 316L stainless steel.

3. The high wear-resistant and corrosion-resistant martensitic stainless steel according to claim 1, characterized in that, The chemical composition of the high wear-resistant martensitic stainless steel, by mass percentage, consists of the following elements: C 0.64%~0.67%, N 0.15%~0.18%, Cr 16.3%~16.7%, Mo 0.9%~1.1%, Si 0.6%~0.8%, Mn 0.35%~0.45%, V 0.3%~0.4%, with the remainder being Fe and unavoidable impurity elements.

4. The high wear-resistant and corrosion-resistant martensitic stainless steel according to claim 3, characterized in that, The high wear-resistant martensitic stainless steel has a hardness > 59.5 HRC, tensile strength > 2100 MPa, yield strength > 1900 MPa, elongation > 5%, pitting potential > 10 mV vs SCE, and corrosion current density under static pure corrosion conditions < 5 × 10⁻⁶ mV. -7 A / cm 2 The wear rate during the abrasion process is reduced by more than 20% compared to 316L stainless steel.

5. A method for preparing highly wear-resistant martensitic stainless steel, characterized in that, Includes the following steps: S1 Smelting and casting: Take the alloying elements according to the chemical composition of any one of claims 1-4, smelt them, and cast them into alloy ingots; S2 Homogenization and Forging: The alloy ingot is subjected to solution treatment, followed by hot forging in the austenitic single-phase region; S3 multi-stage quenching treatment: The forging is heated and held in a stepped temperature range of 620℃~1060℃, and then cooled. S4 cryogenic treatment: Deep cryogenic treatment is performed after quenching; S5 Low-Temperature Composite Tempering: After cryogenic treatment, medium-temperature tempering and low-temperature tempering are performed sequentially.

6. The preparation method according to claim 5, characterized in that, In step S1, the remelting process is carried out at least three times in a vacuum arc melting furnace; in step S2, the solution treatment temperature is 1150℃±10℃, the solution treatment time is 10~14 hours, the forging ratio is 8~9, and the final forging temperature is controlled within the range of 900℃~950℃.

7. The preparation method according to claim 5, characterized in that, In step S3, the forgings are held at temperatures of 630℃±10℃, 850℃±10℃ and 1050℃±10℃ for 10-20 minutes each, and then oil-cooled.

8. The preparation method according to claim 5, characterized in that, In step S4, the cryogenic treatment is carried out in liquid nitrogen for 1 to 8 hours.

9. The preparation method according to claim 5, characterized in that, In step S5, the medium-temperature tempering is held at 500℃±10℃ for 1.5~2.5 hours; the low-temperature tempering is held at 125℃~180℃ for 0.5~1.5 hours.

10. The application of the high wear-resistant martensitic stainless steel according to any one of claims 1-4 or the high wear-resistant martensitic stainless steel prepared by the preparation method according to any one of claims 5-9 in deep-sea equipment.

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