A medium manganese steel with good impact abrasive wear resistance

Abstract

The present invention provides a medium manganese steel with good impact abrasive wear performance, wherein the element composition of the medium manganese steel based on mass percentage includes: C, Si, Mn, Al, Nb, Cr, Ni, V, P, S, Nb; and the medium manganese steel contains more residual austenite, and carbides of Nb or V exist near dislocation entanglement after the medium manganese steel is worn. The medium manganese steel has a TRIP effect due to more residual austenite during the impact wear process, and a large number of dislocations are generated, resulting in hardening of the surface; on the other hand, the medium manganese steel of the present invention also has good toughness. During the wear process, more residual austenite and fine microstructures make the material have a certain toughness to resist impact and shear force, thereby reducing wear and fatigue damage.

Description

Technical Field

[0001] The invention relates to the field of material processing, in particular to a medium manganese steel with good impact abrasive wear performance. Background Art

[0002] Manganese steel is a steel material containing a high concentration of manganese. Manganese steel can be made by adding manganese to steel, and the amount of manganese it contains is usually between 11% and 14%. Manganese steel has high strength, high wear resistance and excellent toughness, so it is widely used in the manufacture of heavy-duty machinery and high-strength structural parts, including: the manufacture of railway vehicles and locomotives, the manufacture of building structural parts, the manufacture of metallurgical equipment and chemical equipment, and the manufacture of ships and marine engineering equipment.

[0003] The medium manganese steel prepared in the prior art is affected by its materials and heat treatment process, thus determining its actual wear resistance and toughness after processing. Therefore, conventional medium manganese steel has limited wear resistance and toughness, while excellent wear resistance and toughness can further expand the application scope of the medium manganese steel material. In order to obtain a medium manganese steel material with better mechanical properties, the present invention provides a medium manganese steel with good impact abrasive wear performance. Summary of the invention

[0004] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a medium manganese steel with good impact abrasive wear performance to solve the problems raised in the above-mentioned background technology. The present invention hardens the surface during the impact wear process, further enhances the wear resistance, and makes the material have higher toughness to resist impact and shear force.

[0005] In order to achieve the above-mentioned purpose, the present invention is realized through the following technical scheme: a medium manganese steel with good impact abrasive wear performance, the element composition of the medium manganese steel based on mass percentage includes: C: 0.04~0.43wt.%, Si: 0.36~1.40wt.%, Mn: 3.80~9.93wt.%, Al: 0.86~3.53wt.%, Nb: 0.04~0.08wt.%, Cr: 0.90~1.36wt.%, Ni: 0.85~1.65%, V: 0.11~0.19 wt.%, P≤0.010%, S≤0.002%, 0.17 wt.%≤Nb+ V≤0.25 wt.%; and the medium manganese steel contains more residual austenite, and after the medium manganese steel is worn, carbides of Nb or V exist near the dislocation entanglement.

[0006] Furthermore, the element composition of the medium manganese steel based on mass percentage includes: C: 0.04wt.%, Si: 1.2wt.%, Mn: 5.80wt.%, Al: 2.6wt.%, Nb: 0.07wt.%, Cr: 1.2wt.%, Ni: 1.3%, V: 0.18 wt.%, P: 0.009%, S: 0.001%, Nb+V: 0.21 wt.%.

[0007] Furthermore, the element composition of the medium manganese steel based on mass percentage includes: C: 0.04wt.%, Si: 1.4wt.%, Mn: 6.10wt.%, Al: 3.5wt.%, Nb: 0.08wt.%, Cr: 1.3wt.%, Ni: 1.6%, V: 0.19 wt.%, P: 0.01%, S: 0.002%, Nb+V: 0.24 wt.%.

[0008] Further, the medium manganese steel is heat treated by the following process: S1, placing the material at 920°C for 15 minutes; S2, cooling it by water quenching until it reaches room temperature; S3, controlling the temperature to reach 680-750°C for annealing for 10 minutes; S4, salt quenching the material until the temperature reaches 145-196°C and keeping it for 15-20 seconds; S5, placing it in a 375-420°C salt bath furnace for insulation for 360 seconds; S6, then taking out the material and cooling the temperature to room temperature by air cooling.

[0009] Furthermore, the C is used to improve the stability of the retained austenite and obtain more retained austenite; the Si is a solid solution strengthening element and is used to improve the strength of the steel; and the Mn plays a role in solid solution strengthening and improves the hardenability and thermodynamic stability of austenite.

[0010] Furthermore, the Al plays a role in refining the grains and increasing the temperature of the two-phase region; the Nb is used to form carbonitrides and refine the microstructure.

[0011] Furthermore, the Cr is used to improve strength, hardness and wear resistance; the Ni is used to increase the strength of the steel while maintaining good plasticity and toughness; and the V is used to refine the grains and improve strength and toughness.

[0012] Beneficial effects of the present invention:

[0013] 1. In the process of impact wear, more residual austenite of the medium manganese steel with good impact abrasive wear performance undergoes TRIP effect and generates a large number of dislocations, resulting in surface hardening; on the other hand.

[0014] 2. The medium manganese steel of the present invention also has better toughness. During the wear process, more residual austenite and fine microstructures make the material have a certain toughness to resist impact and shear force, thereby reducing wear and fatigue damage.

[0015] 3. The mechanical properties of the medium manganese steel of the present invention are as follows: tensile strength: 1080~1750MPa; 20℃ V-notch impact absorption energy: 60~85J elongation: 22.8~46.5%, hardness 289~386HV 0.2 . The hardness after 120 minutes of impact abrasive wear is: 846~970 HV 0.2 ; Wear rate: 83~112mg. Therefore, this medium manganese steel has excellent mechanical properties and wear resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the heat treatment process of manganese steel in the present invention;

[0017] Figure 2 and Figure 3 All are SEM images near the worn surface. DETAILED DESCRIPTION

[0018] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0019] See also Figures 1 to 3 The present invention provides the following technical solution: a medium manganese steel with good impact abrasive wear performance, the element composition of the medium manganese steel based on mass percentage includes: C: 0.04~0.43wt.%, Si: 0.36~1.40wt.%, Mn: 3.80~9.93wt.%, Al: 0.86~3.53wt.%, Nb: 0.04~0.08wt.%, Cr: 0.90~1.36wt.%, Ni: 0.85~1.65%, V: 0.11~0.19 wt.%, P≤0.010%, S≤0.002%, 0.17 wt.%≤Nb+ V≤0.25wt.%.

[0020] The effects provided by each element are as follows

[0021] C: Mainly to ensure the strength of the matrix and a lower transformation temperature, and can improve the stability of retained austenite, obtain more retained austenite, and improve the comprehensive mechanical properties of steel.

[0022] Si: Silicon is a solid solution strengthening element that increases the strength of steel and facilitates the diffusion and distribution of carbon in steel.

[0023] Mn: Manganese can play a role in solid solution strengthening in steel, improving the hardenability and thermodynamic stability of austenite.

[0024] Al: Aluminum can refine grains, improve the stability of austenite, and improve the toughness of steel. The addition of aluminum increases the temperature of the two-phase region, which is beneficial to the design of heat treatment.

[0025] Nb: Niobium can form carbonitrides, refine the microstructure, and play a significant role in precipitation strengthening.

[0026] Cr: Chromium can significantly improve strength, hardness and wear resistance, improve the corrosion resistance of steel and improve the hardenability of steel.

[0027] Ni: can significantly improve the strength of steel while maintaining good plasticity and toughness.

[0028] V: Vanadium is the best precipitation strengthening element for ferrite, and it can refine the grains to a certain extent, improving strength and toughness; the carbides formed by vanadium and carbon can improve the resistance to hydrogen corrosion.

[0029] In this embodiment, the following specific component proportions are provided: C: 0.04wt.%, Si: 1.2wt.%, Mn: 5.80wt.%, Al: 2.6wt.%, Nb: 0.07wt.%, Cr: 1.2wt.%, Ni: 1.3%, V: 0.18 wt.%, P: 0.009%, S: 0.001%, Nb+ V: 0.21 wt.%.

[0030] This embodiment also provides the metallographic structure composition of the above-mentioned medium manganese steel: martensite: 23.3~32.1 vol.%, ferrite: 18.3~26.5 vol.%, and retained austenite 36.4~51.3 vol.%.

[0031] This embodiment also provides the following specific heat treatment method, the steps are as follows:

[0032] S1. Place the material at 920℃ and keep it warm for 15 minutes;

[0033] S2, cooling by water quenching until reaching room temperature;

[0034] S3, control the temperature to 680~750℃ for annealing for 10min;

[0035] S4, salt quench the material until the temperature reaches 145~196℃ and keep it warm for 15~20s;

[0036] S5, put it into a 375~420℃ salt bath furnace for insulation, and the insulation time is 360s;

[0037] S6. The material is then taken out and the temperature is lowered to room temperature by air cooling.

[0038] In this embodiment, the medium manganese steel prepared by the above method is tested and its mechanical properties are as follows: tensile strength: 1080~1750MPa; 20℃ V-notch impact absorption energy: 60~85J elongation: 22.8~46.5%, hardness 289~386HV 0.2 . Tensile strength: 1080~1750MPa; 20℃ V-notch impact absorption energy: 60~85J Elongation: 22.8~46.5%, hardness 289~386HV 0.2 .

[0039] Hardness after 120min impact abrasive wear: 846~970 HV 0.2 ; Wear rate: 83~112mg.

[0040] The principles of the high wear resistance of the medium manganese steel provided by the present invention include: 1. Due to the TRIP effect of more residual austenite during the impact wear process, a large number of dislocations are generated, resulting in surface hardening; 2. The medium manganese steel of the present invention also has good toughness. During the wear process, more residual austenite and fine microstructures make the material have a certain toughness to resist impact and shear force, thereby reducing wear and fatigue damage.

[0041] The attached Figure 2 and 3 The microstructure after wear shows that the structure is significantly refined near the wear surface, dislocations accumulate and interact with each other, which eventually leads to the refinement of the microstructure. In the TEM image, it can be found that Nb or V carbides exist near the dislocation entanglement, which indicates that Nb or V carbides are conducive to pinning dislocations during wear, forming dislocation walls, and ultimately leading to grain refinement. Grain refinement can also increase the hardness of the wear surface, thereby improving wear performance. In addition, grain refinement reduces stress concentration and delays the formation of stress-induced cracks on the surface because there are additional grains that can withstand the crack driving force in the fine grain area.

[0042] The basic principles and main features of the present invention and the advantages of the present invention are shown and described above. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention.

[0043] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A medium manganese steel with good impact abrasive wear resistance, characterized in that: The element composition of the medium manganese steel based on mass percentage includes: C: 0.04~0.43wt.%, Si: 0.36~1.40wt.%, Mn: 3.80~9.93wt.%, Al: 0.86~3.53wt.%, Nb: 0.04~0.08wt.%, Cr: 0.90~1.36wt.%, Ni: 0.85~1.65%, V: 0.11~0.19wt.%, P≤0.010%, S≤0.002%, 0.17 wt.%≤Nb+ V≤0.25 wt.%; and the medium manganese steel contains more residual austenite. After the medium manganese steel is worn, carbides of Nb or V exist near the dislocation entanglement. The 20°C V-notch impact absorption energy of the medium manganese steel is: 60~85J, and the hardness is 289~386HV 0.2 The medium manganese steel is heat treated by the following process: S1. Place the material at 920℃ and keep it warm for 15 minutes; S2. Cool it down by water quenching until it reaches room temperature; S3. Control the temperature to 680~750℃ and anneal it for 10 minutes; S4. Salt quench the material until the temperature reaches 145~196℃ and keep it warm for 15~20s; S5. Put it in a 375~420℃ salt bath furnace for insulation for 360s; S6. Then take out the material and cool it down to room temperature by air cooling.

2. The medium manganese steel with good impact abrasive wear resistance according to claim 1, characterized in that: The element composition of the medium manganese steel based on mass percentage includes: C: 0.04wt.%, Si: 1.2wt.%, Mn: 5.80wt.%, Al: 2.6wt.%, Nb: 0.07wt.%, Cr: 1.2wt.%, Ni: 1.3%, V: 0.18 wt.%, P: 0.009%, S: 0.001%, Nb+V: 0.21 wt.%.

3. The medium manganese steel with good impact abrasive wear resistance according to claim 1, characterized in that: The element composition of the medium manganese steel based on mass percentage includes: C: 0.04wt.%, Si: 1.4wt.%, Mn: 6.10wt.%, Al: 3.5wt.%, Nb: 0.08wt.%, Cr: 1.3wt.%, Ni: 1.6%, V: 0.19 wt.%, P: 0.01%, S: 0.002%, Nb+V: 0.24 wt.%.

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