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CN-117418076-B - Heat treatment method for improving impact performance of 20Cr1Mo1VTiB heat-resistant steel

CN117418076BCN 117418076 BCN117418076 BCN 117418076BCN-117418076-B

Abstract

The application discloses a heat treatment method for improving the impact performance of heat-resistant steel of 20Cr1Mo1VTiB, which belongs to the technical field of heat treatment and comprises the following steps of S1, normalizing and destressing, namely heating a forging to 870-890 ℃, preserving heat for 1-3 h, air cooling to room temperature, S2, quenching and heating, namely heating the forging to 1030-1050 ℃, preserving heat for 1-2 h, S3, quenching and cooling, namely discharging water from a furnace to below 100 ℃ after the heat preservation of the forging is finished, S4, sub-quenching, namely heating the forging to 930-950 ℃ and preserving heat for 1-2 h, S5, sub-quenching and cooling, namely discharging water from the furnace to below 100 ℃ after the heat preservation of the forging is finished, S6, tempering, namely heating the forging to 690-710 ℃, preserving heat for 3-5 h, S7, discharging the forging after the heat preservation is finished, and cooling by tempering, and cooling to room temperature. The scheme solves the problem that the impact plasticity of the 20Cr1Mo1VTiB material for nuclear power and thermal power forgings in the prior art is low.

Inventors

  • TIAN YUAN
  • YAO FANG
  • ZHANG HUI

Assignees

  • 贵州航天新力科技有限公司

Dates

Publication Date
20260505
Application Date
20231205

Claims (5)

  1. 1. A heat treatment method for improving the impact performance of 20Cr1Mo1VTiB heat resistant steel is characterized by comprising the following steps: s1, normalizing and destressing, namely heating a forging to 870-890 ℃, preserving heat for 1-3 hours, and air-cooling to room temperature; S2, quenching and heating, namely heating the forging to 1030-1050 ℃, and preserving heat for 1-2 hours; s3, quenching and cooling, namely discharging water from a furnace to below 100 ℃ after the heat preservation of the forging is finished; S4, sub-temperature quenching, namely heating the forging to 930-950 ℃, and preserving heat for 1-2 hours; S5, sub-temperature quenching cooling, namely discharging the forging after heat preservation is finished, and cooling to below 100 ℃ by water; s6, tempering at a high temperature, namely heating the forging to 690-710 ℃, and preserving heat for 3-5 hours; And S7, tempering and cooling, namely discharging the steel after heat preservation, air-cooling the steel and cooling the steel to room temperature.
  2. 2. The heat treatment method for improving the impact performance of the 20Cr1Mo1VTiB heat-resistant steel, which is disclosed in claim 1, is characterized by comprising the steps of S1, normalizing and destressing, namely heating a forge piece to 870 ℃, and preserving heat for 1h; s2, quenching and heating, namely heating the forging to 1030 ℃ and preserving heat for 1h; s4, sub-temperature quenching, namely heating the forging to 930 ℃ and preserving heat for 1h; s6, tempering at high temperature, namely heating the forge piece to 690 ℃, and preserving heat for 3 hours.
  3. 3. The heat treatment method for improving the impact performance of the 20Cr1Mo1VTiB heat-resistant steel, which is disclosed in claim 1, is characterized by comprising the steps of S1, normalizing and destressing, namely heating a forge piece to 880 ℃, and preserving heat for 2 hours; s2, quenching and heating, namely heating the forging to 1040 ℃, and preserving heat for 1.5h; S4, sub-temperature quenching, namely heating the forging to 940 ℃ and preserving heat for 1.5h; S6, tempering at high temperature, namely heating the forge piece to 700 ℃, and preserving heat for 4 hours.
  4. 4. The heat treatment method for improving the impact performance of the 20Cr1Mo1VTiB heat-resistant steel according to claim 1 is characterized by comprising the following steps of S1, normalizing and destressing, namely heating a forging to 890 ℃, and preserving heat for 3 hours; S2, quenching and heating, namely heating the forging to 1050 ℃, and preserving heat for 2 hours; s4, sub-temperature quenching, namely heating the forging to 950 ℃ and preserving heat for 2 hours; s6, tempering at a high temperature, namely heating the forging to 710 ℃ and preserving heat for 5 hours.
  5. 5. The heat treatment method for improving the impact performance of the heat-resistant steel of 20Cr1Mo1VTiB, which is characterized in that in the step S4, the forging is heated to 940 ℃ for sub-temperature quenching, and in the steps S3 and S5, the forging is discharged from a furnace and cooled to below 90 ℃ after heat preservation.

Description

Heat treatment method for improving impact performance of 20Cr1Mo1VTiB heat-resistant steel Technical Field The invention relates to the technical field of heat treatment, in particular to a heat treatment method for improving the impact performance of 20Cr1Mo1VTiB heat-resistant steel. Background The 20Cr1Mo1VTiB heat resistant steel is a steel for high temperature bolts commonly used in thermal power plants, is widely used for manufacturing the bolts of steam turbines and boilers below 570 ℃, has good comprehensive performance, relaxation resistance and heat resistance, and the steel grade is replaced with 25Cr2MolV steel which is used for years in trend. The steel has improved endurance strength, relaxation resistance and good impact toughness by adding carbide stabilizing elements vanadium and titanium and grain boundary strengthening element boron. The steel grade is subjected to heat treatment by adopting a quenching and tempering process, and the texture form after tempering is bainite. In recent years, the application of 20Cr1Mo1VTiB bolt steel has been promoted to the nuclear power field, and the improvement of the safety coefficient requirement puts higher demands on the matching of strength and toughness. The steel is very sensitive to the change of heat treatment process parameters, the heat treatment process is the most critical factor influencing the toughness matching of the 20Cr1Mo1VTiB steel, and if the heat processing or the heat treatment is not properly controlled, the nuclear power thermal power material is easy to generate macroscopic coarse crystals, so that the product loses toughness and is broken in normal use. Because the nuclear power product has larger specification, the material has higher strength and high impact plasticity, and the nuclear power thermal power product becomes a difficult problem in the field of nuclear power, a heat treatment method for improving the impact performance of 20Cr1Mo1VTiB heat-resistant steel is needed. Disclosure of Invention The invention aims to provide a processing method of 20Cr1Mo1VTiB heat resistant steel, which aims to solve the problem of low impact plasticity of 20Cr1Mo1VTiB materials for nuclear power and thermal power forgings in the prior art. In order to solve the technical problems, the invention provides a heat treatment method for improving the impact performance of 20Cr1Mo1VTiB heat-resistant steel, which comprises the following steps: s1, normalizing and destressing, namely heating a forging to 870-890 ℃, preserving heat for 1-3 hours, and air-cooling to room temperature; S2, quenching and heating, namely heating the forging to 1030-1050 ℃, and preserving heat for 1-2 hours; s3, quenching and cooling, namely discharging water from a furnace to below 100 ℃ after the heat preservation of the forging is finished; S4, sub-temperature quenching, namely heating the forging to 930-950 ℃, and preserving heat for 1-2 hours; S5, sub-temperature quenching cooling, namely discharging the forging after heat preservation is finished, and cooling to below 100 ℃ by water; s6, tempering at a high temperature, namely heating the forging to 690-710 ℃, and preserving heat for 3-5 hours; And S7, tempering and cooling, namely discharging the steel after heat preservation, air-cooling the steel and cooling the steel to room temperature. The invention has the working principle and beneficial effects that the invention firstly carries out normalizing destressing treatment, refines crystal grains, has uniform structure, then carries out quenching at conventional quenching temperature, then carries out sub-temperature quenching at the temperature lower than austenitizing temperature, retains a small amount of ferrite, can obviously improve the toughness of steel, reduces the cold-brittle transition temperature of steel, inhibits the reversible tempering brittleness of steel, improves the impact performance of the material, effectively solves the problem that the impact plasticity of the 20Cr1Mo1VTiB material for thermal power nuclear power is low, improves the impact toughness of the 20Cr1Mo1VTiB material compact forging at-20 ℃ and improves the comprehensive mechanical property of the material. Further, S1, normalizing and stress-relieving treatment, namely heating the forging to 870 ℃ and preserving heat for 1h; s2, quenching and heating, namely heating the forging to 1030 ℃ and preserving heat for 1h; s4, sub-temperature quenching, namely heating the forging to 930 ℃ and preserving heat for 1h; s6, tempering at high temperature, namely heating the forge piece to 690 ℃, and preserving heat for 3 hours. Further, S1, normalizing and destressing treatment, namely heating the forge piece to 880 ℃, and preserving heat for 2 hours; s2, quenching and heating, namely heating the forging to 1040 ℃, and preserving heat for 1.5h; S4, sub-temperature quenching, namely heating the forging to 940 ℃ and preserving heat for 1.5h; S6, tempering at high temperature, name