Search

CN-122013055-A - High-performance high-speed tool steel and heat treatment method thereof

CN122013055ACN 122013055 ACN122013055 ACN 122013055ACN-122013055-A

Abstract

The invention discloses high-performance high-speed tool steel and a heat treatment method thereof, wherein the high-performance high-speed tool steel comprises the following chemical components, by mass, 0.85% -0.95% of C, 0.8% -1.2% of Si, 3.8% -4.5% of Cr, 4.5% -5.5% of Mo, 5.5% -6.5% of W, 2.5% -3.0% of V, 0.1% -0.3% of Nb, 2.0% or less of Co, 0.015% or less of P, 0.015% or less of S, the balance of Fe and unavoidable impurities, the average grain size of carbide in the high-speed tool steel is smaller than 0.5 mu M, and the consumption of expensive cobalt is reduced to an extremely low level (2.0%) on the premise of maintaining even improving performance through the unique silicon-increasing cobalt alloy design, so that the raw material cost can be reduced by 15% -30% compared with the traditional high-speed cobalt steel (such as M42), and the high-speed tool steel has strong market competitiveness.

Inventors

  • LOU JIANAN
  • CHEN YU
  • LOU LAIYONG
  • Lou Laizhe
  • LOU AIYAN
  • YU GUANGHAO
  • WU ZHANYONG
  • YU GUANGYUAN

Assignees

  • 浙江鑫哲模具有限公司

Dates

Publication Date
20260512
Application Date
20260414

Claims (10)

  1. 1. A high-performance high-speed tool steel is characterized by comprising the following chemical components, by mass, 0.85% -0.95% of C, 0.8% -1.2% of Si, 3.8% -4.5% of Cr, 4.5% -5.5% of Mo, 5.5% -6.5% of W, 2.5% -3.0% of V, 0.1% -0.3% of Nb, less than or equal to 2.0% of Co, less than or equal to 0.015% of P, less than or equal to 0.015% of S, the balance of Fe and unavoidable impurities; The average grain size of carbide in the high-speed tool steel is less than 0.5 mu m.
  2. 2. The high-performance high-speed tool steel according to claim 1, wherein the mass percentage of Co is 0% -1.5%.
  3. 3. The high performance high speed tool steel of claim 1, wherein C is 0.88% -0.94%, si is 0.9% -1.1%, nb is 0.15% -0.25%.
  4. 4. A high performance high speed tool steel according to any one of claims 1-3, characterized in that the method of manufacturing the high performance high speed tool steel comprises the steps of: s1, spray forming, namely atomizing molten steel which is smelted and meets the component requirements by inert gas, and depositing atomized liquid drops on a water-cooled substrate to form a preformed billet; s2, performing hot isostatic pressing densification, namely performing hot isostatic pressing treatment on the preformed billet at the temperature of 1050-1150 ℃ and the pressure of 120-150 MPa, and preserving heat and pressure for 2-4 hours; S3, large deformation hot working, namely heating the densified blank to 1000-1120 ℃ and performing thermomechanical working with true strain being more than or equal to 1.0.
  5. 5. The high performance high speed tool steel of claim 1, wherein the thermo-mechanical working in S3 is multi-directional forging or high reduction rolling.
  6. 6. A method for heat treatment of high performance high speed tool steel according to any one of claims 1 to 5, comprising the sequential steps of: A. austenitizing, namely heating a workpiece to 1190-1210 ℃ and preserving heat; B. Carrying out ultrahigh-pressure gas quenching, namely carrying out forced cooling on a workpiece by inert gas with the pressure of 6-10 bar; C. cryogenic treatment, namely placing the quenched workpiece in an environment of-150 ℃ to-196 ℃ and preserving heat for 2-4 hours; D. And (3) carrying out composite cycle tempering, namely carrying out three tempering on the work piece subjected to the deep cooling treatment, wherein the first tempering temperature and the second tempering temperature are 555-565 ℃, the third tempering is carried out in a nitrocarburizing atmosphere of 565-575 ℃, and the work piece is cooled after heat preservation for 3-4 hours.
  7. 7. The heat treatment method according to claim 6, wherein the temperature of the first tempering and the second tempering in the step D is 560 ℃ and the temperature of the third tempering is 570 ℃ after heat preservation for 1 hour and air cooling.
  8. 8. The heat treatment method according to claim 6, wherein the inert gas in B is high purity nitrogen or nitrogen-helium mixture.
  9. 9. The heat treatment method according to claim 6, wherein the nitrocarburizing atmosphere used for the third tempering in D is composed of ammonia gas, carbon-containing gas and trace carbon dioxide.
  10. 10. A high performance tool article produced from the high performance high speed tool steel of any one of claims 1-5, and treated by the heat treatment method of any one of claims 6-9.

Description

High-performance high-speed tool steel and heat treatment method thereof Technical Field The invention belongs to the technical field of metal materials, and particularly relates to high-performance high-speed tool steel and a heat treatment method thereof. Background High speed tool steel is a key material for manufacturing high speed cutting tools, hot and cold dies and high performance bearings, the core of which is high hardness, hardness retention at high temperatures (red hardness) and sufficient toughness. Traditional high performance high speed steels (e.g., M42, M35 series) promote red hardness by adding higher levels of cobalt (typically 5-12 wt.%) but cobalt is a strategically rare metal, expensive and subject to large supply fluctuations, resulting in high material costs. In the aspect of alloy design, the traditional thought is mainly focused on adjusting the content and proportion of main alloy elements such as tungsten, molybdenum, vanadium, chromium and the like. Elemental silicon is generally considered as a residual element or is severely limited to a lower content (e.g., < 0.5%), and too high a level is considered to impair toughness. Uniformity and refinement of carbide are key to determining performance. The high-speed steel produced by the traditional arc furnace smelting and forging process inevitably has carbide segregation, is easy to form a coarse ledeburite eutectic carbide network, has still unsatisfactory size and distribution uniformity even after subsequent forging and crushing, becomes the origin of fatigue cracks, and limits the further improvement of the toughness and the wear resistance of the material. In the preparation process, although the powder metallurgy technology (such as atomization powder preparation and hot isostatic pressing) can effectively improve carbide distribution, the process is complex, the equipment investment is huge, the cost is high, and the powder metallurgy technology is difficult to be applied to conventional cutter materials on a large scale. The conventional casting and forging process is difficult to fundamentally solve the macrosegregation problem. In terms of heat treatment, the main stream process is oil quenching or conventional pressure gas quenching followed by multiple high temperature tempers (typically three tempers at 560 ℃). The process is mature but has limitations that 1) oil quenching pollutes the environment and the deformation of a workpiece is large, the cooling capacity of the conventional gas quenching (2-4 bar) on the workpiece with a large section may be insufficient, 2) cryogenic treatment is usually taken as an optional or independent subsequent process and is not systematically integrated into a core heat treatment process, the potential of stabilizing tissues and improving dimensional stability is not fully exerted, 3) surface strengthening (such as nitriding and PVD coating) and substrate heat treatment are completely separated subsequent processes, the production period and the cost are increased, and the binding force and performance matching between a surface strengthening layer and a substrate may have an optimization space. Therefore, the prior art has the outstanding contradiction that the pursuit of ultra-high performance often depends on high cobalt to cause cost surge, the traditional preparation process restricts tissue uniformity, and the dispersed heat treatment and surface treatment processes cannot realize the maximization of material performance potential. In view of the foregoing, an innovative technical solution is needed in the industry, which can reduce the cost from the alloy design source, achieve tissue ultrafining and homogenization through preparation process innovation, and synchronously optimize the substrate and the surface properties by adopting an integrated heat treatment technology, so as to achieve breakthrough balance between the comprehensive properties and the cost. Disclosure of Invention In order to meet the above-mentioned needs in the background, the present invention provides a high-performance high-speed tool steel and a heat treatment method thereof, which at least partially solve the above-mentioned problems. According to the technical scheme, the high-performance high-speed tool steel comprises the following chemical components, by mass, 0.85% -0.95% of C, 0.8% -1.2% of Si, 3.8% -4.5% of Cr, 4.5% -5.5% of Mo, 5.5% -6.5% of W, 2.5% -3.0% of V, 0.1% -0.3% of Nb, 2.0% of Co, 0.015% of P, 0.015% of S and the balance of Fe and unavoidable impurities; The average grain size of carbide in the high-speed tool steel is less than 0.5 mu m. Preferably, the mass percentage of Co is 0% -1.5%. Preferably, the content of C is 0.88% -0.94%, the content of Si is 0.9% -1.1%, and the content of Nb is 0.15% -0.25%. Preferably, the preparation method of the high-performance high-speed tool steel comprises the following steps: s1, spray forming, namely atomizing molten steel which is smelted and