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CN-118291727-B - Preparation method of RAFM steel with excellent strong plasticity and layered structure

CN118291727BCN 118291727 BCN118291727 BCN 118291727BCN-118291727-B

Abstract

The application belongs to the field of metal material preparation, and particularly relates to a preparation method of a layered structure RAFM steel with excellent strong plasticity, which comprises the steps of 1) preserving heat for more than 2 hours at 1100-1200 ℃, 2) carrying out hot rolling treatment on the steel, carrying out ultra-fast cooling to room temperature after five times of hot rolling, and 3) tempering the rolled steel below a recrystallization temperature to finally obtain the high-strength plastic layered structure RAFM steel, wherein the RAFM steel is any one of CLAM steel, CLF-1 steel, 9Cr2WVTa steel, EUROFER steel, F82H steel or JLF-1 steel. The preparation process of RAFM steel overcomes the technical bias, the rolled steel billet is not subjected to solution treatment or high-temperature tempering, but is directly tempered below the recrystallization temperature, the plasticizing mechanism of a layered structure is utilized, the strong plasticity of the steel is improved, and the strength and the plasticity of the steel are improved at room temperature and at-196 ℃.

Inventors

  • ZHOU JINHUA
  • JIANG YIFU
  • REN JUNGANG
  • YIN XIAOWEI
  • WANG LIN
  • LIU JINTAO

Assignees

  • 沈阳工程学院

Dates

Publication Date
20260512
Application Date
20240514

Claims (6)

  1. 1. A preparation method of RAFM steel with a layered structure and excellent strong plasticity is characterized by comprising the following steps: 1) Homogenizing and annealing the RAFM steel ingot at 1100-1200 ℃ for 2-4 hours; 2) Carrying out primary rolling treatment on the steel ingot subjected to the homogenization annealing, wherein the initial rolling temperature is 1120-1180 ℃, rolling the steel from 60-67mm to 35-40mm in two passes, the single rolling reduction is 23-26%, and the final rolling temperature is 1030-1160 ℃, and then entering a waiting temperature zone to suspend rolling; 3) The billet after primary rolling is rolled for the second time, the initial rolling temperature is 830-870 ℃, the steel is rolled from 35-40mm to 10-16mm through three passes, the single rolling reduction is 23-26%, the final rolling temperature is 790-850 ℃, and the final rolling temperature is lower than the recrystallization temperature; 4) After hot rolling, the hot-rolled steel is cooled to room temperature ultra-quickly, the ultra-fast cooling process is a water cooling process; 5) And tempering the cooled steel plate at 700-730 ℃ for 15-30min to obtain the RAFM steel with the layered structure with excellent strong plasticity, wherein the layered grain size of the RAFM steel with the layered structure is 8-10 mu M, the ferrite subgrain size is 150-170nm, the M 23 C 6 carbide is 25-30nm and the volume fraction is 0.25-0.3.
  2. 2. The method for preparing the RAFM steel with the layered structure and excellent in plasticity according to claim 1, wherein the initial rolling process is that the initial rolling temperature is 1150 ℃, the final rolling temperature is 1050 ℃, the steel is rolled from 65mm to 37mm through twice rolling, and the rolling deformation of each pass is 25%.
  3. 3. The method for preparing the RAFM steel with the layered structure and excellent in plasticity according to claim 1, wherein the secondary rolling process is carried out at a starting temperature of 850 ℃ and a finishing temperature of 800 ℃ and the steel is rolled from 37mm to 15mm through three times of rolling, and the rolling deformation of each time is 25%.
  4. 4. The preparation method of the RAFM steel with the layered structure and excellent strong plasticity as claimed in claim 1, wherein the cooling water temperature in the step 4) is room temperature, the water pressure is 0.35-0.6MPa, and the water quantity is 180-300m 3 .
  5. 5. The method for preparing the RAFM steel with the layered structure and excellent strong plasticity according to claim 1, wherein the RAFM steel with the layered structure has the room temperature yield strength of 900-980MPa, the elongation after break of 25-27%, the yield strength at-196 ℃ of 1350-1400MPa and the elongation after break of 23-26%.
  6. 6. The method for producing a layered-structure RAFM steel having excellent strength and plasticity as claimed in claim 1, wherein the RAFM steel is any one of CLAM steel, CLF-1 steel, 9Cr2WVTa steel, EUROFER97 steel, F82H steel or JLF-1 steel.

Description

Preparation method of RAFM steel with excellent strong plasticity and layered structure Technical Field The invention belongs to the field of metal material preparation, and particularly relates to a preparation method of RAFM steel with a layered structure and excellent strong plasticity. Background Low-activation ferrite/martensite steel (RAFM steel) still has good mechanical properties, thermal conductivity and thermal expansion resistance under strong irradiation conditions, and is considered as a preferred structural material currently applied to nuclear fusion reactors. However, when the steel is in service for a long time under the irradiation condition, the microstructure of the steel can be subjected to irradiation hardening under the action of long-time irradiation, so that the toughness of the steel is obviously reduced, and the ductile-brittle transition temperature is continuously increased. When the ductile-brittle transition temperature of the steel exceeds room temperature, it runs the risk of brittle failure at room temperature. It is extremely important to improve the room temperature and low temperature strength and plasticity of the RAFM steel. Patent document CN109457095A discloses a strengthening treatment method of a CLAM steel, which can effectively refine the subgrain boundary and carbide size in the steel through non-recrystallization zone rolling and post-rolling rapid cooling process, so that the yield strength and tensile strength of the steel are obviously improved, and the maximum elongation of the steel is correspondingly reduced. Patent document CN117123789a discloses a method for preparing heat-resistant irradiation-resistant ultra-fine grain martensitic steel by adding nanoscale Sc4Zr3O12 ceramic oxide powder to CLAM steel. The nano-scale Sc4Zr3O12 precipitation effectively improves the strength of the steel, but the maximum elongation of the steel is obviously reduced as well. From the prior art, refining the sizes of the subgrain and the precipitated phases in the steel can effectively improve the yield and the tensile strength of the steel, however, the plasticity of the steel can be correspondingly reduced, and the mismatch between the steel strong plasticity greatly limits the practical application. In the traditional equiaxed crystal structure steel, the larger atom mismatch degree at the crystal boundary can effectively prevent the dislocation from moving, thereby improving the strength of the steel. However, the obstruction of the dislocation by the grain boundary also easily causes local stress concentration so as to promote crack initiation and reduce the elongation after fracture of the steel. In order to improve the normal temperature/low temperature yield strength and the plasticity performance of martensitic steel, a new technology for breaking through the existing strong plasticity contradiction and simultaneously improving the strong plasticity of the steel at the room temperature and the low temperature is needed to be developed. Disclosure of Invention The invention aims to provide a preparation method of a layered structure RAFM steel with excellent strong plasticity, which overcomes the defects of the prior art, and aims to solve the strong plasticity contradiction of martensitic steel, form layered grain boundaries different from equiaxed grains in the steel, so that stress and cracks uniformly spread along the grain boundary direction, local concentration of the stress is avoided, initiation and expansion of the cracks are delayed, and the strong plasticity of the steel at room temperature and low temperature of-196 ℃ is improved. In order to achieve the technical purpose, the invention is realized by the following technical scheme: A preparation method of a RAFM steel with excellent plasticity comprises the following steps of 1) carrying out homogenizing annealing treatment on an RAFM steel ingot at 1100-1200 ℃ for 2-4h, 2) carrying out primary rolling treatment on the steel ingot after homogenizing annealing, wherein the initial rolling temperature is 1120-1180 ℃, rolling the steel from 60-67mm to 35-40mm through two passes, the single rolling reduction is 23-26%, the final rolling temperature is 1030-1160 ℃ and then entering a temperature waiting area for pause rolling, 3) carrying out secondary rolling on a steel billet after primary rolling, the secondary rolling initial rolling temperature is 830-870 ℃, rolling the steel from 35-40mm to 10-16mm through three passes, the single rolling reduction is 23-26%, the final rolling temperature is 790-850 ℃ and the final rolling temperature is lower than the recrystallization temperature, 4) carrying out ultra-fast cooling to room temperature after hot rolling, and the ultra-fast cooling process is a water cooling process, and 5) carrying out tempering on the cooled steel plate at 700-730 ℃ for 15-30min to obtain the RAFM steel with excellent plasticity. The initial rolling process comprises the steps of