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CN-122013070-A - Low-cost ultrahigh-strength martensitic steel material and preparation method and application thereof

CN122013070ACN 122013070 ACN122013070 ACN 122013070ACN-122013070-A

Abstract

The invention belongs to the technical field of powder metallurgy materials and intelligent manufacturing, and relates to a low-cost ultrahigh-strength martensitic steel material, a preparation method and application thereof, wherein the material comprises the following chemical elements of 1.0-5.0wt% of Cr, 9.0-14.0wt% of Ni, 5.0-12.9wt% of Co, 6.5-9.5wt% of Mo, trace amount of V-0.5wt% and the balance of Fe. The invention ensures excellent yield strength and simultaneously has excellent extensibility through systematic reconstruction of the composition of the material, and has market competitiveness in cost. The material is particularly suitable for preparing parts by a metal injection molding process, and the obtained steel structural member has the yield strength of 2000-2100 MPa and the elongation rate of more than 6 percent, or has the yield strength of 1800-2000 MPa and the elongation rate of more than 8 percent.

Inventors

  • HU WANYANG
  • FANG CHIQIANG
  • LUO XIANZHEN
  • Fei Risheng
  • CHEN XINGUO

Assignees

  • 湖州慧金材料科技有限公司

Dates

Publication Date
20260512
Application Date
20260211

Claims (10)

  1. 1. A low-cost ultra-high strength martensitic steel material is characterized by comprising the following chemical elements of 1.0-5.0wt% of Cr, 9.0-14.0wt% of Ni, 5.0-12.9wt% of Co, 6.5-9.5wt% of Mo, trace amount of V-0.5wt% and the balance of Fe and unavoidable impurity elements.
  2. 2. The low-cost ultrahigh-strength martensitic steel material according to claim 1, wherein the mass percentage of Cr, ni, co, mo, V elements is 1.0-3.0wt% of Cr, 12.0-14.0wt% of Ni, 5.0-9.0wt% of Co, 8.0-9.5wt% of Mo and trace amount of V-0.50wt%.
  3. 3. The low-cost ultrahigh-strength martensitic steel material according to claim 1, wherein the mass percentage of Cr, ni, co, mo, V elements is 1.0-3.0wt% of Cr, 12.0-14.0wt% of Ni, 9.0-12.9wt% of Co, 6.5-8.0wt% of Mo and trace amount of V-0.50wt%.
  4. 4. The low-cost ultrahigh-strength martensitic steel material according to claim 1, wherein the mass percentage of Cr, ni, co, mo, V elements is 3.0-5.0wt% of Cr, 9.0-12.0wt% of Ni, 5.0-9.0wt% of Co, 8.0-9.5wt% of Mo and trace amount of V-0.50wt%.
  5. 5. The low-cost ultrahigh-strength martensitic steel material according to claim 1, wherein the mass percentage of Cr, ni, co, mo, V elements is 3.0-5.0wt% of Cr, 9.0-12.0wt% of Ni, 9.0-12.9wt% of Co, 6.5-8.0wt% of Mo and trace amount of V-0.50wt%.
  6. 6. The low-cost ultrahigh-strength martensitic steel material according to claim 1, wherein the mass percentage of Cr, ni, co, mo, V elements is 1.0-5.0wt% of Cr, 9.0-14.0wt% of Ni, 5.0-12.9wt% of Co, 7.1-9.5wt% of Mo and trace amount of V-0.50wt%.
  7. 7. The low cost ultra high strength martensitic steel material according to claim 1, further comprising Nb and/or Cu, the mass percentage content of Nb or Cu not exceeding 0.2%.
  8. 8. A steel structure, characterized in that it is formed by a metal injection molding process using the low-cost ultra-high strength martensitic steel material according to any one of claims 1-7.
  9. 9. The steel structural member according to claim 8, wherein the elongation is 6% or more while the yield strength is 2000MPa to 2100MPa, or 8% or more while the yield strength is more than 1800MPa to 2000 MPa.
  10. 10. Use of a low cost high strength martensitic steel stock as claimed in any one of claims 1-7 or a steel structure as claimed in any one of claims 8-9 in 3C products, automotive products, aerospace products, medical products.

Description

Low-cost ultrahigh-strength martensitic steel material and preparation method and application thereof Technical Field The invention belongs to the technical field of powder metallurgy materials and intelligent manufacturing, relates to a metal material, and in particular relates to a low-cost ultrahigh-strength martensitic steel material, and a preparation method and application thereof. Background The metal injection molding (Metal Injection Molding, MIM) is a near net forming manufacturing method which integrates a plastic injection molding process and a powder metallurgy technology, and is widely applied to mass production of metal parts with complex geometric shapes. However, the sintered part prepared from MIM is limited by a sintering densification mechanism, and generally only can reach 96% -99.5% of theoretical density, internal pores are difficult to completely eliminate, and further densification and mechanical properties cannot be improved through subsequent cold/thermoplastic deformation (such as rolling, forging, etc.). Therefore, the traditional MIM material faces a significant performance bottleneck in ultra-high strength application scenarios. In recent years, in the field of 3C electronics (especially products such as folding screen smart phones, wearable devices, and lightweight notebook computers), higher demands are being made on the weight saving and high strength of structural members. For example, the key force bearing components such as the rotating shaft of the folding screen are required to have ultrahigh strength, good toughness and excellent fatigue resistance. In view of the high complexity of such component geometries, conventional machining processes are not only costly, low in material utilization, but also difficult to meet the precise dimensional control requirements, so MIM technology is becoming the dominant manufacturing route. However, 3C applications also have stringent requirements on the elongation and fracture toughness of the material. Because the inherent porous microstructure of the MIM sintered body is easy to become a source of crack initiation and propagation, the improvement of the plasticity and toughness of the material is obviously restricted. Existing studies indicate that when the elongation of MIM ultra-high strength steel exceeds 6%, further synergistic strength and plasticity becomes very challenging. The applicant performs systematic optimization aiming at the problem by earlier research (see Chinese invention patent application CN 118109759A) to develop a high-toughness martensitic steel material, wherein typical chemical components (mass percent) of the high-toughness martensitic steel material are 7.0-9.0 wt% of Cr, 7.0-9.0 wt% of Ni, 9.0-15.0 wt% of Co, 5.5-7.0 wt% of Mo, 0.05-0.5 wt% of Nb, less than or equal to 0.03 wt% of C, and the balance of Fe and unavoidable impurity elements. The component prepared by adopting the component system and through the MIM process can realize yield strength of >1900 MPa (under partial conditions of >2000 MPa) and elongation rate of >5%, and shows good strong plastic matching. Notably, all of the ultra-high strength steels for MIM currently disclosed (yield strength: 1800: MPa) generally rely on high levels of cobalt (Co) element to strengthen the matrix and stabilize the microstructure, wherein the Co content is generally not less than 13 wt%. However, cobalt is a strategically scarce metal, and market price fluctuations are severe and high for a long time, and continue to rise in recent years. Therefore, the cost of the MIM ultra-high strength steel raw material is high, and the large-scale application of the MIM ultra-high strength steel raw material in the cost sensitive fields such as consumer electronics and the like is severely restricted. Disclosure of Invention The invention aims to supplement the metal injection molding material in the prior art, and provides the metal injection molding material with yield strength of more than 1800MPa, elongation of more than 8 percent, and the yield strength can be changed in the range of 1800-2100 MPa according to different heat treatment processes, so that the corresponding good elongation and low cost can be obtained. In a first aspect of the present invention, a low cost ultra high strength martensitic steel material is provided. A low cost ultra high strength martensitic steel material comprising the following chemical elements: 1.0-5.0wt% of Cr, 9.0-14.0wt% of Ni, 5.0-12.9wt% of Co, 6.5-9.5wt% of Mo, trace amount of V-0.5wt% and the balance of Fe. The Cr element mainly provides corrosion resistance of the steel. Chromium and oxygen form a stable chromium oxide layer, which can prevent the martensitic steel surface from reacting with oxygen and water in the environment, thereby protecting the martensitic steel from corrosion. Chromium is also a ferritic element in the material, and too high chromium can reduce the strength of the material. Ni element is also a t