Search

CN-121992308-A - High-strength stainless steel and preparation method thereof

CN121992308ACN 121992308 ACN121992308 ACN 121992308ACN-121992308-A

Abstract

The application relates to high-strength stainless steel and a preparation method thereof, and relates to the technical field of high-strength stainless steel and preparation thereof. By reducing the alloy design of nickel, medium nitrogen and copper, the stainless steel material has metastable austenite structure, and triggers the transformation induced plasticity effect and the twinning induced plasticity effect when being stressed. The metastable austenite is converted into martensite when stressed due to the transformation induced plasticity effect, a large amount of energy is absorbed, dislocation movement is effectively hindered by the twin induced plasticity effect, and the stainless steel material has excellent damage tolerance and better impact resistance and dent resistance due to the synergistic effect of the two mechanisms.

Inventors

  • LI HANYE
  • LI SONGYUE
  • WANG JIAN
  • Xiang Linghe
  • LI JIANHAO
  • ZHU YUNE

Assignees

  • 浙江丰业集团有限公司

Dates

Publication Date
20260508
Application Date
20260226

Claims (7)

  1. 1. The high-strength stainless steel is characterized by comprising ：Cr 17.0-19.0%,Ni 5.5-7.0%,Cu 2.5-3.5%,Mn 2.0-4.0%,Si 0.8-1.5%,Mo 0.5-1.0%,N 0.15-0.25%,C 0.08-0.12%,P≤0.03%,S≤0.03%, weight percent of Fe as the rest; The stainless steel material has a metastable austenite structure, and can trigger a transformation induced plasticity effect and a twinning induced plasticity effect when stressed; The preparation method of the high-strength stainless steel comprises the following steps: S1, smelting and hot rolling, namely smelting molten steel according to a formula, casting into a plate blank, and hot rolling at 1100-1200 ℃; s2, solution treatment, namely, rapidly cooling after heat preservation at 1050-1100 ℃; S3, cold rolling, namely cold rolling the sheet material subjected to solution treatment by 30% -50% of deformation; s4, critical annealing, namely short-time annealing at 850-950 ℃ for 1-5min, and then rapid cooling.
  2. 2. A high strength stainless steel according to claim 1, wherein the austenitic volume fraction of the stainless steel material is 70-80%.
  3. 3. The high strength stainless steel of claim 1, wherein the stainless steel material has a yield strength of not less than 600MPa, a tensile strength of not less than 900MPa, and an elongation of not less than 40%.
  4. 4. The high strength stainless steel according to claim 1, wherein said step S1 is an arc furnace smelted and then refined by AOD or VOD.
  5. 5. The high strength stainless steel according to claim 1, wherein the rapid cooling in step S2 is performed by water quenching.
  6. 6. The high strength stainless steel according to claim 1, wherein the cold rolling of step S3 is performed in multiple passes, intermediate annealing is performed between passes, the intermediate annealing temperature is 800-900 ℃, and the holding time is 1-3min.
  7. 7. The high strength stainless steel according to claim 1, wherein the critical annealing in step S4 is performed in a protective atmosphere, and the annealing is followed by cooling with gas quenching or water mist at a cooling rate of not less than 50 ℃.

Description

High-strength stainless steel and preparation method thereof Technical Field The application relates to the technical field of high-strength stainless steel and preparation thereof, in particular to high-strength stainless steel and a preparation method thereof. Background Stainless steel materials are widely used in the manufacturing field due to their excellent corrosion resistance and formability. Among them, austenitic stainless steel such as 304 stainless steel has been a common material. However, the strength of the traditional austenitic stainless steel is generally low, the yield strength is usually about 250MPa, so that the problems of permanent deformation, scratch damage and dent easily occur in the use process of the stainless steel material, and the service life is seriously influenced. With the increasing demands of consumers for stainless steel durability, the development of stainless steel materials having both high strength and good toughness has become an important development direction in the art. At present, in order to improve the strength of stainless steel, solid solution strengthening and precipitation strengthening are mainly performed by adding interstitial atoms such as carbon and nitrogen or displacement elements such as titanium, but the method often leads to the reduction of the plasticity and toughness of the material and the increase of the cost, or the method introduces deformation martensitic transformation for strengthening by large deformation cold working, but the method can deteriorate the formability of the material and the strengthening effect is unevenly distributed. Therefore, the development of a product which realizes the cooperative promotion of the strength and the toughness of the stainless steel material on the premise of not depending on expensive alloy elements or complex processes has practical significance. Disclosure of Invention The application provides high-strength stainless steel and a preparation method thereof, and the high-strength stainless steel has the effect of cooperatively improving the strength and toughness of the stainless steel. In a first aspect, the present application provides a high strength stainless steel, which adopts the following technical scheme: A high-strength stainless steel comprises ：Cr 17.0-19.0%,Ni 5.5-7.0%,Cu 2.5-3.5%,Mn 2.0-4.0%,Si 0.8-1.5%,Mo 0.5-1.0%,N 0.15-0.25%,C 0.08-0.12%,P≤0.03%,S≤0.03%, mass percent of Fe as the rest; The stainless steel material has a metastable austenite structure, and can trigger a transformation induced plasticity effect and a twinning induced plasticity effect when stressed; The preparation method of the high-strength stainless steel comprises the following steps: S1, smelting and hot rolling, namely smelting molten steel according to a formula, casting into a plate blank, and hot rolling at 1100-1200 ℃; s2, solution treatment, namely, rapidly cooling after heat preservation at 1050-1100 ℃; S3, cold rolling, namely cold rolling the sheet material subjected to solution treatment by 30% -50% of deformation; s4, critical annealing, namely short-time annealing at 850-950 ℃ for 1-5min, and then rapid cooling. By adopting the technical scheme, the mass percentage of the chromium element controlled to be 17.0-19.0% is the basis of the stainless steel capable of forming a compact passivation film so as to improve the corrosion resistance. In order to realize metastability, the content of expensive nickel element is reduced to a lower level of 5.5-7.0%, so that the thermodynamic stability of austenite is moderately reduced, preconditions are created for the transformation induced plasticity effect, and the cost is reduced. Meanwhile, in order to compensate the austenite stability lost due to nickel reduction and realize strengthening, 0.15-0.25% of nitrogen element is introduced. Nitrogen is used as a powerful austenite stabilizer and a gap solid solution strengthening element, and the accurate regulation and control of the performance can be realized at more economic cost. On the basis, 2.0-4.0% of manganese can assist in stabilizing austenite and promoting formation of twin crystals, 0.8-1.5% of silicon is used for improving oxidation resistance and inhibiting carbide precipitation, and 0.5-1.0% of molybdenum is used for enhancing pitting corrosion resistance of stainless steel. 2.5-3.5% copper can serve multiple functions, namely, it not only provides solid solution strengthening, but also becomes an ideal stress concentration point when stressed in an austenitic matrix, thereby triggering local martensitic transformation and twinning behavior. Through the proportion of elements in the scheme, the Md 30/50 temperature of the material, namely the temperature at which 50% of austenite is transformed into martensite under deformation is regulated and controlled to be near the room temperature, so that the stainless steel is exactly in a critical state of mechanical properties under the daily use env