A high-performance low-carbon wear-resistant steel and a heat treatment method for improving the performance of the low-carbon wear-resistant steel

Abstract

The application discloses a kind of high-performance low-carbon wear-resistant steel and the heat treatment method for improving the performance of low-carbon wear-resistant steel, belongs to the technical field of wear-resistant material preparation.The heat treatment method for improving the performance of low-carbon wear-resistant steel includes the following steps: S1: low-carbon wear-resistant steel is heated to 530-570 DEG C and is kept warm, then pulse treatment is carried out;S2: the low-carbon wear-resistant steel after pulse treatment is heated to 900-940 DEG C and is kept warm, then pulse treatment is carried out, and water quenching is carried out after pulse ends;S3: the low-carbon wear-resistant steel after water quenching treatment is heated and kept warm, then pulse treatment is carried out, and finally water quenching treatment is carried out.The application fully considers the effect of fine-grain strengthening, precipitation strengthening and solid solution strengthening three synergistic strengthening mechanisms in composition design and heat treatment process, and also ensures that wear-resistant steel has sufficient toughness by the new heat treatment method of applying electric pulse, so that low-carbon wear-resistant steel has sufficient strength, hardness, can guarantee good wear resistance while having high toughness.

Description

Technical Field

[0001] The invention belongs to the technical field of wear-resistant material preparation, and particularly relates to a high-performance low-carbon wear-resistant steel and a heat treatment method for improving the performance of the low-carbon wear-resistant steel. Background Art

[0002] Wear-resistant steel plates are widely used in industries with particularly harsh working conditions, such as mining, construction, agriculture, cement production, ports, electricity, and metallurgy. Traditional wear-resistant steel mainly uses low-carbon martensitic wear-resistant steel, which is produced through quenching and low-temperature tempering processes. The traditional heat treatment production process is greatly restricted by the capacity of the quenching / tempering equipment, resulting in low production efficiency and great production difficulty. The uniformity of the surface and core of the steel plate is poor.

[0003] To improve the performance of wear-resistant steel castings, Chinese invention patent CN 104388821A discloses a TiC particle-reinforced, duplex-structured, high-plasticity wear-resistant steel plate and its manufacturing method. This patent discloses a TiC-reinforced wear-resistant steel with a retained austenite volume fraction of 6-12%, which exhibits better wear resistance than HB450. However, this wear-resistant steel exhibits a room-temperature impact energy of >20 J, which decreases with decreasing temperature, resulting in poor low-temperature impact performance. Chinese invention patent CN 114369763A discloses a retained austenite-toughened wear-resistant steel and its manufacturing method. The retained austenite volume fraction is 10% to 14%. The steel's wear resistance is enhanced by increasing the Ti content to form a large number of dispersed TiC particles, while Mn, Ni, and Cr are used to enhance austenite stability. However, this patent discloses a high carbon and alloying content, resulting in poor weldability. Chinese invention patent CN 109763072 B discloses a thick, high-wear-resistant steel plate and a method for manufacturing the same. The thick, high-wear-resistant steel plate has a microstructure consisting of martensite and retained austenite, with a volume fraction of retained austenite of 10-20%. Using an online quenching and partitioning process, the plate is produced to achieve a 95% high-performance wear-resistant steel with a thickness of 40-400 mm and a core hardness no less than that of the surface. However, this production method requires that the steel plate be immediately placed in a heat treatment furnace for partitioning after cooling to 150-250°C after rolling. This production connection is difficult to achieve or mass-produce in current production processes.

[0004] In summary, in view of the shortcomings of the existing heat treatment technology of duplex wear-resistant steel, a new heat treatment method is developed to improve the performance of alloy wear-resistant steel and adapt to increasingly complex wear conditions. Summary of the Invention

[0005] To address the shortcomings of the prior art, the present invention provides a high-performance low-carbon wear-resistant steel and a heat treatment method for improving the performance of low-carbon wear-resistant steel. Through a heat treatment process, the present invention precipitates multi-scale carbides, ferrite, and martensite in the alloyed wear-resistant steel, reducing dislocations and achieving high surface hardness, yield strength, and sufficient impact toughness.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A heat treatment method for improving the performance of low-carbon wear-resistant steel comprises the following steps:

[0008] S1: Heat the low carbon wear-resistant steel to 530-570℃ and keep it warm, then perform pulse treatment.

[0009] S2: The low carbon wear-resistant steel after pulse treatment is heated to 900-940℃ and kept warm, then pulse treated, and water quenched after the pulse is completed.

[0010] S3: The low carbon wear-resistant steel after water quenching is heated and kept warm, then pulse treated, and finally water quenched.

[0011] The mass percentages of the components in the low-carbon wear-resistant steel are C: 0.05% to 0.2%, Si: 0.2% to 0.4%, Mn: 0.8% to 2.2%, Gr: 0.5% to 1.5%, Ti: 0.05% to 0.15%, V: 0.1% to 0.2%, Ni: 0.3% to 0.8%, Mo: 0.2% to 0.6%, Nb: 0.05% to 0.12%, P<0.03%, S<0.02%, and the rest are Fe and unavoidable impurities.

[0012] As a preferred embodiment of the present invention, in the pulse treatment, the pulse width is 1-20 μs, the pulse interval is 10-100 μs, and the pulse current density is 50-500 A / mm 2 .

[0013] As a preferred embodiment of the present invention, in S1, the electric pulse is stopped when the pulse treatment temperature is above 570°C; in S2, the electric pulse is stopped when the pulse treatment temperature is above 940°C; in S3, the electric pulse is stopped when the pulse treatment temperature is above 850°C.

[0014] The pulse processing width, interval and current density in S1, S2 and S3 are the same.

[0015] As a preferred embodiment of the present invention, in S1, the heating rate is 50-70°C / h, and the holding time is 20-30 minutes.

[0016] As a preferred embodiment of the present invention, in S2, the heating temperature rise rate is 50-70°C / h, and the holding time is 30-50 minutes; the water temperature during water quenching is 20-35°C, the mass ratio of low-carbon wear-resistant steel to water is less than 1:8, and the water cooling time during water quenching is more than 30 minutes.

[0017] As a preferred embodiment of the present invention, in S2, the heating temperature is 810-850°C, the heating rate is 50-70°C / h, and the holding time is 50-70 minutes; the water temperature is 20-35°C, the mass ratio of the casting to water is less than 1:8, and the water cooling time during water quenching is not more than 60 minutes.

[0018] The present invention also claims protection for high-performance low-carbon wear-resistant steel prepared by the heat treatment method for improving the performance of low-carbon wear-resistant steel.

[0019] As a preferred embodiment of the present invention, the microstructure of the high-performance low-carbon wear-resistant steel includes martensite, ferrite, and multi-scale carbides.

[0020] As a preferred embodiment of the present invention, the volume percentage of ferrite in the microstructure of the high performance low carbon wear-resistant steel is 10%-20%.

[0021] Ferrite has good plasticity and toughness, but low strength and hardness. The present invention controls the ferrite content within 10%-20%, which can effectively improve the plasticity and toughness of the material and maintain the hardness and strength of the material.

[0022] As a preferred embodiment of the present invention, the multi-scale carbide includes micron-scale precipitation phase, submicron-scale precipitation phase, and nanoscale precipitation phase; the average size of the micron-scale precipitation phase is 2-10 μm, the average size of the submicron-scale precipitation phase is 200-500 nm, and the average size of the nanoscale precipitation phase is 30-80 nm.

[0023] Principle of the present invention:

[0024] The present invention adopts a new heat treatment process based on the characteristics of Ti-V-Nb alloy to precipitate second phase particles of different sizes in low carbon wear-resistant steel and reduce dislocations. The change in dislocation structure caused by applying pulse current varies depending on the characteristics of each phase. Defect sites, usually dislocation nuclei, are the nucleation sites of NbC precipitation phase in low carbon wear-resistant steel. Therefore, dislocation density or dislocation structure may be one of the important factors of NbC in current-induced precipitation hardening. The main existence state of Ti, V, and Nb in austenite is mainly related to the equilibrium solubility product. Since NbC has the smallest solubility product, it precipitates in austenite first; thereafter, a large number of TiC particles are precipitated with NbC as the particle and grow to form micron-scale and submicron-scale (Ti, Nb)C composite precipitation phases, and then VC is dispersed and precipitated during a lower temperature period to form a nanometer-scale second phase.

[0025] The new heat treatment process described in the present invention includes: staged solid solution treatment, staged electric pulse treatment, and two quenching treatments. The staged solid solution treatment can make the structure of low-carbon wear-resistant steel more uniform, refine the grain size to a certain extent, and improve the morphology, size, and distribution of the second phase. It also allows the majority of the primary second phase particles to be solid-dissolved in the austenite matrix, facilitating their precipitation in a more uniform form during subsequent heat treatment. Furthermore, the purpose of the first quenching is to obtain a fine and uniform martensitic structure after water quenching, thereby ensuring that the grains do not grow excessively during the second heating and holding period. The purpose of the second quenching is that the second phase particles precipitated in the early stage will not be completely dissolved into the matrix. In the subsequent quenching process, dispersed micron-sized precipitates will be precipitated as particles. At the same time, nano-sized VC particles will be precipitated due to the presence of V. The remaining small-sized austenite will form harder martensite at a higher cooling rate, so that the matrix structure of the wear-resistant steel forms a fine martensite structure and small ferrite islands are distributed between its grain boundaries, ensuring that the wear-resistant steel has good strength and toughness. At the same time, micron-sized, submicron-sized and nano-sized precipitation phases will be dispersed and precipitated to refine the grains.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) The method of the present invention fully considers the effects of the synergistic strengthening mechanism of fine grain strengthening, precipitation strengthening and solid solution strengthening in the composition design and heat treatment process. At the same time, the new heat treatment method of applying electric pulses ensures that the wear-resistant steel has sufficient toughness, so that the low-carbon wear-resistant steel has sufficient strength and hardness to ensure good wear resistance while having high toughness, and effectively prevents the wear-resistant steel from cracking and failure due to local stress concentration.

[0028] (2) The method of the present invention can promote the decomposition of austenite and the full dissolution of primary carbides by setting the isothermal treatment at 550±20℃, and promote the recrystallization of austenite at 920±10℃, which has the effect of refining the grains and generating ferrite to enhance the toughness and plasticity of low-carbon wear-resistant steel.

[0029] (3) The high-performance low-carbon wear-resistant steel prepared by the heat treatment for improving the performance of the low-carbon wear-resistant steel has a matrix structure of ferrite and ferrite, a uniform structure and a fine grain size, and a large number of nano-scale, submicron-scale and micron-scale precipitates dispersedly distributed. Therefore, the high-performance low-carbon wear-resistant steel has a high surface hardness and yield strength, while also ensuring sufficient impact toughness. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a flow chart of the heat treatment process of the present invention.

[0031] Figure 2This is the metallographic structure diagram of the low-carbon wear-resistant steel after heat treatment in Example 1.

[0032] Figure 3 This is an SEM image of the micron-, submicron-, and nanometer-scale precipitates in the low-carbon wear-resistant steel after heat treatment in Example 1. DETAILED DESCRIPTION

[0033] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0034] Example 1

[0035] The heat treatment method for improving the performance of low-carbon wear-resistant steel in this embodiment includes the following steps:

[0036] (1) According to the chemical composition of low carbon wear-resistant steel (mass percentage of C: 0.12%, Si: 0.2-0.4%, Mn: 1.84%, Gr: 0.87%, Ti: 0.98%, V: 0.15%, Ni: 0.42%, Mo: 0.36%, Nb: 0.10%, P < 0.03%, S < 0.02%, the rest is Fe and unavoidable impurities), the ingredients are prepared and then smelted to obtain a low carbon wear-resistant steel casting with a size of 100 mm × 50 mm × 50 mm.

[0037] (2) The low carbon wear-resistant steel casting was heated to 550°C in an open heating furnace at a heating rate of 70°C / h. After the holding time was 20 minutes, an AC pulse current was applied for pulse treatment. The pulse width was 1 μs, the pulse interval was 10 μs, and the pulse current density was 50 A / mm 2 .

[0038] (3) The wear-resistant steel after pulse treatment was heated to 920℃ and kept at this temperature for 30min at a heating rate of 70℃ / h. Then, an AC pulse current was applied for pulse treatment. The pulse width was 1μs, the pulse interval was 10μs, and the pulse current density was 50A / mm 2 , water quenching is carried out after the end; the water temperature before water quenching is 23°C, the mass ratio of wear-resistant steel castings and water is 1:8, the water temperature after water quenching is 31°C, and the water cooling time is 60min.

[0039] (4) The low-carbon wear-resistant steel casting after water quenching was heated to 830°C at a heating rate of 70°C / h, and the holding time was 70 min. Then an AC pulse current was applied with a pulse width of 1 μs, a pulse interval of 10 μs, and a pulse current density of 50 A / mm 2 .

[0040] (5) The wear-resistant steel casting after the pulse in step (4) is water quenched, the water temperature before water quenching is 25°C, the mass ratio of the wear-resistant steel casting to water is 1:8, the water temperature after the water quenching is 31°C, and the water cooling time is 60 minutes.

[0041] Example 2

[0042] The heat treatment method for improving the performance of low-carbon wear-resistant steel in this embodiment includes the following steps:

[0043] (1) According to the chemical composition of low carbon wear-resistant steel (mass percentage of C: 0.09%, Si: 0.28%, Mn: 1.98%, Gr: 1.32%, Ti: 0.10%, V: 0.18%, Ni: 0.63%, Mo: 0.45%, Nb: 0.09%, P < 0.03%, S < 0.02%, the rest is Fe and unavoidable impurities), the ingredients are prepared and then smelted to obtain a wear-resistant steel casting with a size of 150 mm × 40 mm × 40 mm.

[0044] (2) The low carbon wear-resistant steel casting was heated to 530°C in an open heating furnace at a heating rate of 70°C / h. After the holding time was 25 minutes, an AC pulse current was applied for pulse treatment. The pulse width was 10 μs, the pulse interval was 50 μs, and the pulse current density was 100 A / mm 2 .

[0045] (3) The wear-resistant steel after pulse treatment was heated to 920℃ and kept at this temperature for 40min at a heating rate of 70℃ / h. Then, an AC pulse current was applied for pulse treatment. The pulse width was 10μs, the pulse interval was 50μs, and the pulse current density was 100A / mm 2 , water quenching is carried out after the end; the water temperature before water quenching is 23°C, the mass ratio of wear-resistant steel castings and water is 1:9, the water temperature after water quenching is 31°C, and the water cooling time is 60min.

[0046] (4) The low-carbon wear-resistant steel casting after water quenching was heated to 810°C at a heating rate of 70°C / h, and the holding time was 70 min. Then an AC pulse current was applied with a pulse width of 10 μs, a pulse interval of 50 μs, and a pulse current density of 100 A / mm 2 .

[0047] (5) The wear-resistant steel casting after the pulse in step (4) is water quenched, the water temperature before water quenching is 23°C, the mass ratio of the wear-resistant steel casting to water is 1:9, the water temperature after water quenching is 31°C, and the water cooling time is 60 minutes.

[0048] Example 3

[0049] The heat treatment method for improving the performance of low-carbon wear-resistant steel in this embodiment includes the following steps:

[0050] (1) According to the chemical composition of low carbon wear-resistant steel (mass percentage of C: 0.16%, Si: 0.34%, Mn: 0.21%, Gr: 1.18%, Ti: 0.13%, V: 0.14%, Ni: 0.52%, Mo: 0.39%, Nb: 0.10%, P < 0.03%, S < 0.02%, the rest is Fe and unavoidable impurities), the ingredients are prepared and then smelted to obtain a wear-resistant steel casting with a size of 200 mm × 30 mm × 30 mm.

[0051] (2) The low carbon wear-resistant steel casting was heated to 570°C in an open heating furnace at a heating rate of 70°C / h. After holding for 30 minutes, an AC pulse current was applied for pulse treatment. The pulse width was 20 μs, the pulse interval was 100 μs, and the pulse current density was 500 A / mm 2 .

[0052] (3) The wear-resistant steel after pulse treatment was heated to 920℃ and kept at this temperature for 40min at a heating rate of 70℃ / h. Then, an AC pulse current was applied for pulse treatment. The pulse width was 20μs, the pulse interval was 100μs, and the pulse current density was 500A / mm 2 , water quenching is carried out after the end; the water temperature before water quenching is 24°C, the mass ratio of wear-resistant steel castings and water is 1:10, the water temperature after water quenching is 30°C, and the water cooling time is 60min.

[0053] (4) The low-carbon wear-resistant steel casting after water quenching was heated to 810°C at a heating rate of 70°C / h, and the holding time was 70 min. Then an AC pulse current was applied with a pulse width of 20 μs, a pulse interval of 100 μs, and a pulse current density of 500 A / mm 2 .

[0054] (5) The wear-resistant steel casting after the pulse in step (4) is water quenched, the water temperature before water quenching is 24°C, the mass ratio of the wear-resistant steel casting to water is 1:10, the water temperature after water quenching is 30°C, and the water cooling time is 60 minutes.

[0055] Comparative Example 1

[0056] The heat treatment method for improving the performance of low-carbon wear-resistant steel in this comparative example comprises the following steps:

[0057] (1) According to the chemical composition of low carbon wear-resistant steel (mass percentage of C: 0.12%, Si: 0.2-0.4%, Mn: 1.84%, Gr: 0.87%, Ti: 0.98%, V: 0.15%, Ni: 0.42%, Mo: 0.36%, Nb: 0.10%, P < 0.03%, S < 0.02%, the rest is Fe and unavoidable impurities), the ingredients are prepared and then smelted to obtain a wear-resistant steel casting with a size of 100 mm × 50 mm × 50 mm.

[0058] (2) The low-carbon wear-resistant steel casting was heated to 920°C in an open heating furnace at a heating rate of 70°C / h. The holding time was 70 minutes before water quenching. The water temperature before water quenching was 25°C, the mass ratio of the wear-resistant steel casting to water was 1:8, and the water temperature after water quenching was 34°C. The water cooling time was 60 minutes.

[0059] (3) The low-carbon wear-resistant steel casting after water quenching was heated to 830°C at a heating rate of 70°C / h, kept at this temperature for 70 min, and then water quenched. The water temperature before water quenching was 25°C, the mass ratio of the wear-resistant steel casting to water was 1:8, the water temperature after water quenching was 32°C, and the water cooling time was 60 min.

[0060] Comparative Example 2

[0061] The heat treatment method for improving the performance of low-carbon wear-resistant steel in this comparative example comprises the following steps:

[0062] (1) According to the chemical composition of low carbon wear-resistant steel (mass percentage of C: 0.12%, Si: 0.2-0.4%, Mn: 1.84%, Gr: 0.87%, Ti: 0.98%, V: 0.15%, Ni: 0.42%, Mo: 0.36%, Nb: 0.10%, P < 0.03%, S < 0.02%, the rest is Fe and unavoidable impurities), the ingredients are prepared and then smelted to obtain a low carbon wear-resistant steel casting with a size of 100 mm × 50 mm × 50 mm.

[0063] (2) The low carbon wear-resistant steel casting was heated to 550 °C in an open heating furnace with a heating rate of 70 °C / h and a holding time of 70 min.

[0064] (3) The wear-resistant steel after insulation was heated to 920℃ and kept at this temperature for 70min at a heating rate of 70℃ / h. After the end, water quenching was performed. The water temperature before water quenching was 25℃, the mass ratio of the wear-resistant steel casting to water was 1:8, the water temperature after water quenching was 34℃, and the water cooling time was 60min.

[0065] Comparative Example 3

[0066] The heat treatment method for improving the performance of low-carbon wear-resistant steel in this comparative example comprises the following steps:

[0067] (1) According to the chemical composition of low carbon wear-resistant steel (mass percentage of C: 0.12%, Si: 0.2-0.4%, Mn: 1.84%, Gr: 0.87%, Ti: 0.98%, V: 0.15%, Ni: 0.42%, Mo: 0.36%, Nb: 0.10%, P < 0.03%, S < 0.02%, the rest is Fe and unavoidable impurities), the ingredients are prepared and then smelted to obtain a low carbon wear-resistant steel casting with a size of 100 mm × 50 mm × 50 mm.

[0068] (2) The low carbon wear-resistant steel casting was heated to 550 °C in an open heating furnace with a heating rate of 70 °C / h and a holding time of 20 min.

[0069] (3) The wear-resistant steel after insulation was heated to 920℃, kept at this temperature for 30min, and heated at a rate of 70℃ / h, and then water quenched; the water temperature before water quenching was 23℃, the mass ratio of the wear-resistant steel casting to water was 1:8, the water temperature after water quenching was 31℃, and the water cooling time was 60min.

[0070] (4) The low-carbon wear-resistant steel casting after water quenching was heated to 830°C at a heating rate of 70°C / h and kept at this temperature for 70 min. Then, water quenching was performed. The water temperature before water quenching was 25°C, the mass ratio of the wear-resistant steel casting to water was 1:8, and the water temperature after water quenching was 31°C. The water cooling time was 60 min.

[0071] Comparative Example 4

[0072] The heat treatment method for improving the performance of low-carbon wear-resistant steel in this comparative example comprises the following steps:

[0073] (1) According to the chemical composition of low carbon wear-resistant steel (mass percentage of C: 0.12%, Si: 0.2-0.4%, Mn: 1.84%, Gr: 0.87%, Ti: 0.98%, V: 0.15%, Ni: 0.42%, Mo: 0.36%, Nb: 0.10%, P < 0.03%, S < 0.02%, the rest is Fe and unavoidable impurities), the ingredients are prepared and then smelted to obtain a low carbon wear-resistant steel casting with a size of 100 mm × 50 mm × 50 mm.

[0074] (2) The low carbon wear-resistant steel casting was heated to 550 °C in an open heating furnace with a heating rate of 70 °C / h and a holding time of 20 min.

[0075] (3) Heat the insulated wear-resistant steel to 920°C for 30 minutes at a heating rate of 70°C / h, then pass an AC pulse current for pulse treatment with a pulse width of 1 μs, a pulse interval of 10 μs, and a pulse current density of 50 A / mm 2, water quenching is carried out after the end; the water temperature before water quenching is 23°C, the mass ratio of wear-resistant steel castings and water is 1:8, the water temperature after water quenching is 31°C, and the water cooling time is 60min.

[0076] (4) The low-carbon wear-resistant steel casting after water quenching was heated to 830°C at a heating rate of 70°C / h, and the holding time was 70 min. Then an AC pulse current was applied with a pulse width of 1 μs, a pulse interval of 10 μs, and a pulse current density of 50 A / mm 2 .

[0077] (5) The wear-resistant steel casting after the pulse in step (4) is water quenched, the water temperature before water quenching is 25°C, the mass ratio of the wear-resistant steel casting to water is 1:8, the water temperature after the water quenching is 31°C, and the water cooling time is 60 minutes.

[0078] Comparative Example 5

[0079] The heat treatment method for improving the performance of low-carbon wear-resistant steel in this comparative example comprises the following steps:

[0080] (1) According to the chemical composition of low carbon wear-resistant steel (mass percentage of C: 0.12%, Si: 0.2-0.4%, Mn: 1.84%, Gr: 0.87%, Ti: 0.98%, V: 0.15%, Ni: 0.42%, Mo: 0.36%, Nb: 0.10%, P < 0.03%, S < 0.02%, the rest is Fe and unavoidable impurities), the ingredients are prepared and then smelted to obtain a low carbon wear-resistant steel casting with a size of 100 mm × 50 mm × 50 mm.

[0081] (2) The low carbon wear-resistant steel casting was heated to 550°C in an open heating furnace at a heating rate of 70°C / h. After the holding time was 20 minutes, an AC pulse current was applied for pulse treatment. The pulse width was 1 μs, the pulse interval was 10 μs, and the pulse current density was 50 A / mm 2 .

[0082] (3) The pulse-treated wear-resistant steel was heated to 920°C, kept at this temperature for 30 min, and heated at a rate of 70°C / h, and then water quenched. The water temperature before quenching was 23°C, the mass ratio of the wear-resistant steel casting to water was 1:8, and the water temperature after quenching was 31°C. The water cooling time was 60 min.

[0083] (4) The low-carbon wear-resistant steel casting after water quenching was heated to 830°C at a heating rate of 70°C / h, and the holding time was 70 min. Then an AC pulse current was applied with a pulse width of 1 μs, a pulse interval of 10 μs, and a pulse current density of 50 A / mm 2 .

[0084] (5) The wear-resistant steel casting after the pulse in step (4) is water quenched, the water temperature before water quenching is 25°C, the mass ratio of the wear-resistant steel casting to water is 1:8, the water temperature after the water quenching is 31°C, and the water cooling time is 60 minutes.

[0085] Comparative Example 6

[0086] The heat treatment method for improving the performance of low-carbon wear-resistant steel in this comparative example comprises the following steps:

[0087] (1) According to the chemical composition of low carbon wear-resistant steel (mass percentage of C: 0.12%, Si: 0.2-0.4%, Mn: 1.84%, Gr: 0.87%, Ti: 0.98%, V: 0.15%, Ni: 0.42%, Mo: 0.36%, Nb: 0.10%, P < 0.03%, S < 0.02%, the rest is Fe and unavoidable impurities), the ingredients are prepared and then smelted to obtain a low carbon wear-resistant steel casting with a size of 100 mm × 50 mm × 50 mm.

[0088] (2) The low carbon wear-resistant steel casting was heated to 550°C in an open heating furnace at a heating rate of 70°C / h. After the holding time was 20 minutes, an AC pulse current was applied for pulse treatment. The pulse width was 1 μs, the pulse interval was 10 μs, and the pulse current density was 50 A / mm 2 .

[0089] (3) The wear-resistant steel after pulse treatment was heated to 920℃ and kept at this temperature for 30min at a heating rate of 70℃ / h. Then, an AC pulse current was applied for pulse treatment. The pulse width was 1μs, the pulse interval was 10μs, and the pulse current density was 50A / mm 2 , water quenching is carried out after the end; the water temperature before water quenching is 23°C, the mass ratio of wear-resistant steel castings and water is 1:8, the water temperature after water quenching is 31°C, and the water cooling time is 60min.

[0090] (4) The low-carbon wear-resistant steel casting after water quenching was heated to 830°C at a heating rate of 70°C / h, and water quenched after holding for 70 min. The water temperature before water quenching was 25°C, the mass ratio of wear-resistant steel casting to water was 1:8, and the water temperature after water quenching was 31°C. The water cooling time was 60 min.

[0091] Comparative Example 7

[0092] The heat treatment method for improving the performance of low-carbon wear-resistant steel in this comparative example comprises the following steps:

[0093] (1) According to the chemical composition of low carbon wear-resistant steel (mass percentage of C: 0.12%, Si: 0.2-0.4%, Mn: 1.84%, Gr: 0.87%, Ti: 0.98%, V: 0.15%, Ni: 0.42%, Mo: 0.36%, Nb: 0.10%, P < 0.03%, S < 0.02%, the rest is Fe and unavoidable impurities), the ingredients are prepared and then smelted to obtain a low carbon wear-resistant steel casting with a size of 100 mm × 50 mm × 50 mm.

[0094] (2) The low carbon wear-resistant steel casting was heated to 550°C in an open heating furnace at a heating rate of 70°C / h. After the holding time was 20 minutes, an AC pulse current was applied for pulse treatment. The pulse width was 1 μs, the pulse interval was 10 μs, and the pulse current density was 50 A / mm 2 .

[0095] (3) The wear-resistant steel after pulse treatment was heated to 920℃ and kept at this temperature for 30min at a heating rate of 70℃ / h. Then, an AC pulse current was applied for pulse treatment. The pulse width was 1μs, the pulse interval was 10μs, and the pulse current density was 50A / mm 2 , the air is cooled to 31℃.

[0096] (4) The low-carbon wear-resistant steel casting after water quenching was heated to 830°C at a heating rate of 70°C / h, and the holding time was 70 min. Then an AC pulse current was applied with a pulse width of 1 μs, a pulse interval of 10 μs, and a pulse current density of 50 A / mm 2 .

[0097] (5) The wear-resistant steel casting after the pulse in step (4) is water quenched, the water temperature before water quenching is 25°C, the mass ratio of the wear-resistant steel casting to water is 1:8, the water temperature after the water quenching is 31°C, and the water cooling time is 60 minutes.

[0098] Comparative Example 8

[0099] The heat treatment method for improving the performance of low-carbon wear-resistant steel in this comparative example comprises the following steps:

[0100] (1) According to the chemical composition of low carbon wear-resistant steel (mass percentage of C: 0.12%, Si: 0.2-0.4%, Mn: 1.84%, Gr: 0.87%, Ti: 0.98%, V: 0.15%, Ni: 0.42%, Mo: 0.36%, Nb: 0.10%, P < 0.03%, S < 0.02%, the rest is Fe and unavoidable impurities), the ingredients are prepared and then smelted to obtain a low carbon wear-resistant steel casting with a size of 100 mm × 50 mm × 50 mm.

[0101] (2) The low carbon wear-resistant steel casting was heated to 550°C in an open heating furnace at a heating rate of 70°C / h. After the holding time was 20 minutes, an AC pulse current was applied for pulse treatment. The pulse width was 1 μs, the pulse interval was 10 μs, and the pulse current density was 50 A / mm 2 .

[0102] (3) The wear-resistant steel after pulse treatment was heated to 920℃ and kept at this temperature for 30min at a heating rate of 70℃ / h. Then, an AC pulse current was applied for pulse treatment. The pulse width was 1μs, the pulse interval was 10μs, and the pulse current density was 50A / mm 2 , water quenching is carried out after the end; the water temperature before water quenching is 23°C, the mass ratio of wear-resistant steel castings and water is 1:8, the water temperature after water quenching is 31°C, and the water cooling time is 60min.

[0103] (4) The low-carbon wear-resistant steel casting after water quenching was heated to 830°C at a heating rate of 70°C / h, and the holding time was 70 min. Then an AC pulse current was applied with a pulse width of 1 μs, a pulse interval of 10 μs, and a pulse current density of 50 A / mm 2 .

[0104] (5) Cooling the wear-resistant steel casting in air after the pulse in step (4) is completed.

[0105] Effect Examples

[0106] Figure 2 The metallographic structure of the low-carbon wear-resistant steel after heat treatment in Example 1 can be seen from the figure. The matrix structure of the high-performance low-carbon wear-resistant steel is composed of ferrite and martensite, of which the volume percentage of ferrite is about 16%. Its structure is relatively fine and uniform, with a grain size of about 10μm. From the fine grains, it can be inferred that fine grain strengthening has made a significant contribution to the improvement of yield strength. And from Figure 2 The figure also shows the presence of numerous discontinuous micron-sized precipitates within the matrix. These are primarily rectangular or square in shape, ranging in size from 2 to 10 μm. These micron-sized precipitates are primarily composed of TiC coated with NbC. Their distribution as hard particles on the matrix surface can significantly increase the surface hardness of the wear-resistant steel.

[0107] Figure 3This is an SEM image of the micron-, submicron-, and nanometer-scale precipitates in the low-carbon wear-resistant steel after heat treatment in Example 1. As can be seen from the figure, there are precipitates in multiple scales of micron, submicron, and nanometer in the steel. The number of micron-scale precipitates is relatively small, and their sizes range from a few microns to ten microns; the number of nanometer- and submicron-scale precipitates is relatively large, and their sizes range from tens to hundreds of nanometers; the micron-scale precipitates are square in shape and unevenly distributed, while the nanometer-scale precipitates are dispersed throughout the surface of the matrix, and their shapes are mostly irregular spheres, ellipsoids, and rods. The micron-scale precipitates can increase the surface hardness of the wear-resistant steel, while the nanometer- and submicron-scale precipitates can increase the strength of the wear-resistant steel by hindering dislocation movement.

[0108] Table 1 Microstructure and mechanical properties of low carbon wear-resistant steel prepared in Examples 1-3 and Comparative Examples 1-8

[0109]

[0110]

[0111] The microstructure data in Table 1 show that, at equivalent strength levels, the elongations of Examples 1-3 are all higher than those of Comparative Examples 1-8. The strength, elongation, room-temperature impact energy, and surface hardness of the Examples are significantly improved compared to the Comparative Examples, with the room-temperature impact energy being no less than 30 J. This comparison demonstrates that Examples 1-3 of the present invention exhibit excellent overall mechanical properties. The microstructures of Examples 1-3 are martensite and ferrite, with a ferrite volume fraction of 10-20%. The microstructure of Comparative Example 1 is also martensite and ferrite, while the microstructure of Comparative Example 2 is pure martensite. The main reason for the differences in ferrite volume fraction and average grain size in Examples 1-3 is the different heating temperatures during the second quenching. The higher the heating temperature, the more energy the steel block receives, the easier it is for the grains to grow, and the less ferrite is produced. The microstructure of Comparative Example 1 is similar to that of Example 1, but the average grain size is larger. This is primarily due to the lack of graded heat preservation during the heat treatment performed in Comparative Example 1. Consequently, the mechanical properties of Comparative Example 1 are lower than those of Examples 1-3. This is primarily due to the lack of graded heating and preservation, resulting in a less uniform microstructure than in Examples 1-3. Comparative Example 2 produces a pure martensitic structure because the lack of a second quench prevents the formation of a dual-phase structure of martensite and ferrite. Although the yield strength, tensile strength, and surface hardness of Comparative Example 2 are higher than those of Examples 1-3, its impact toughness is significantly reduced. This can lead to premature cracking and failure of the wear-resistant steel under conditions with high impact energy, as Comparative Example 2 exhibits a single martensitic structure with poor strength and toughness. According to Example 1 and Comparative Examples 3-6, Comparative Example 3 was not pulse treated, and its microstructure was 96% martensite + 4% ferrite with a particle size of 15 μm. This shows that the principle of the pulse treatment is to reduce dislocations and increase carbide precipitation, resulting in a wear-resistant complex phase steel with higher surface hardness and yield strength. However, the elongation and room temperature impact energy of the material obtained without pulse treatment in Comparative Example 3 were significantly reduced. Comparative Examples 4-6 lacked the first, second, and third pulse treatments, respectively. The microstructures of the high-performance low-carbon wear-resistant steels prepared all included martensite, ferrite, and multi-scale carbides, and the average particle size was 13-14 μm. The elongation and room temperature impact energy were significantly reduced, indicating that the principle of the first, second, and third pulse treatments on the material properties is that the pulse treatment eliminates some of the dislocations generated in the organization, increases the toughness of the material, increases the precipitation of carbides, and improves the elongation and room temperature impact energy of the material. According to Example 1 and Comparative Examples 7-8, Comparative Examples 7-8 respectively replace the first and second water quenching with air cooling, which can produce pearlite structure, so that the yield strength of the material is slightly improved, but the elongation of the material is significantly reduced, and the hardness and impact toughness of the material are reduced.

[0112] Table 2 Wear weight loss of low carbon wear-resistant steels prepared in Examples 1-3 and Comparative Examples 1-8 after different wear times

[0113]

[0114] Table 2 shows the wear weight loss of low-carbon wear-resistant steels prepared in Examples 1-3 and Comparative Examples 1-8 at different wear times under 2J impact energy. As can be seen from Table 2, the wear performance of Examples 1-3 is significantly improved compared to Comparative Examples 1-8, demonstrating excellent wear resistance. Comparative Example 1 exhibits poor wear resistance due to its uneven microstructure and low surface hardness. Furthermore, the lack of ferrite in the microstructure of Comparative Example 2 easily leads to stress concentration and premature fracture under impact wear conditions. Compared to the examples, the materials prepared in Comparative Examples 3-6 lack pulse treatment and exhibit inferior wear resistance. This is primarily because pulse treatment promotes carbide precipitation, reduces dislocations, improves room-temperature impact energy, and enhances wear resistance. In contrast to Example 1 and Comparative Examples 7-8, the first and second water quenches in Comparative Examples 7-8 were replaced with air cooling, producing pearlite. While this slightly improved the yield strength, the elongation was significantly reduced, and the hardness and impact toughness decreased, resulting in reduced wear resistance.

[0115] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A heat treatment method for improving the performance of low-carbon wear-resistant steel, characterized in that: The steps include: S1: Heat the low carbon wear-resistant steel to 530-570℃ and keep it warm, then perform pulse treatment. When the pulse treatment temperature is above 570℃, stop the electric pulse. S2: The low-carbon wear-resistant steel after pulse treatment is heated to 900-940°C and kept warm, and then pulse treated. When the pulse treatment temperature is above 940°C, the electric pulse is stopped, and water quenching is performed after the pulse is completed; S3: heating the low-carbon wear-resistant steel after water quenching to 810-850°C and keeping the temperature, then performing pulse treatment. When the pulse treatment temperature is above 850°C, stopping the electric pulse, and finally performing water quenching to obtain high-performance low-carbon wear-resistant steel; The mass percentages of the components in the low-carbon wear-resistant steel are C: 0.05% to 0.2%, Si: 0.2% to 0.4%, Mn: 0.8% to 2.2%, Gr: 0.5% to 1.5%, Ti: 0.05% to 0.15%, V: 0.1% to 0.2%, Ni: 0.3% to 0.8%, Mo: 0.2% to 0.6%, Nb: 0.05% to 0.12%, P < 0.03%, S < 0.02%, and the rest are Fe and unavoidable impurities; The microstructure of the high-performance low-carbon wear-resistant steel includes martensite, ferrite, and multi-scale carbides.

2. The heat treatment method for improving the performance of low-carbon wear-resistant steel according to claim 1, characterized in that: In the pulse treatment, the pulse width is 1-20 μs, the pulse interval is 10-100 μs, and the pulse current density is 50-500 A / mm 2 .

3. The heat treatment method for improving the performance of low-carbon wear-resistant steel according to claim 1, characterized in that: In the step S1, the heating rate is 50-70°C / h, and the holding time is 20-30 minutes.

4. The heat treatment method for improving the performance of low-carbon wear-resistant steel according to claim 1, characterized in that: In S2, the heating rate is 50-70°C / h, and the holding time is 30-50 minutes; the water temperature during the water quenching process is 20-35°C, the mass ratio of low-carbon wear-resistant steel to water is less than 1:8, and the water cooling time during the water quenching is more than 30 minutes.

5. High-performance low-carbon wear-resistant steel prepared by the heat treatment method for improving the performance of low-carbon wear-resistant steel according to any one of claims 1 to 4.

6. The high performance low carbon wear-resistant steel according to claim 5, characterized in that: The microstructure of the high-performance low-carbon wear-resistant steel includes martensite, ferrite, and multi-scale carbides.

7. The high performance low carbon wear-resistant steel according to claim 6, characterized in that: The volume percentage of ferrite in the microstructure of the high-performance low-carbon wear-resistant steel is 10%-20%.

8. The high performance low carbon wear-resistant steel according to claim 6, characterized in that: The multi-scale carbide includes a micron-scale precipitation phase, a submicron-scale precipitation phase, and a nanometer-scale precipitation phase; the average size of the micron-scale precipitation phase is 2-10 μm, the average size of the submicron-scale precipitation phase is 200-500 nm, and the average size of the nanometer-scale precipitation phase is 30-80 nm.

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