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CN-117904408-B - Flash heat treatment process of ultra-high strength steel plate

CN117904408BCN 117904408 BCN117904408 BCN 117904408BCN-117904408-B

Abstract

A flash heat treatment process of an ultra-high strength steel plate belongs to the field of metal materials. The chemical composition of the ultra-high strength steel plate is C0.25～0.35％、Si0.3～1.5％、Mn2.0～2.5％、Ni0.4～0.6％、Cr0.3～0.8％、Mo0.1～0.5％、Al0.01～0.04％、B0.0015～0.0020％、Nb0.02～0.05％、Ti0.005～0.020％、N≤0.003％、S≤0.010％、P≤0.010％, and the balance of Fe. The preparation method comprises the steps of heating a rolled plate at 600-650 ℃ for 20-40 min, at 100-150 ℃ per second to 900-950 ℃, at 5-15 s, cooling to room temperature at 50-100 ℃ per second, and at 150-250 ℃ for 60-120 min to obtain the ultra-high strength steel plate, wherein the yield strength (R p0.2 ) is more than or equal to 1100MPa, the tensile strength (R m ) is more than or equal to 1200MPa, the elongation (A) is more than or equal to 12%, and the impact toughness value at-40 ℃ is more than or equal to 70J.

Inventors

  • WANG XUEMIN
  • ZHU HAIBIN
  • LI XIUCHENG
  • XIE ZHENJIA
  • WANG XUELIN
  • ZHAO YANQING
  • SHI SHUAI
  • HUANG XINGUI

Assignees

  • 北京科技大学

Dates

Publication Date
20260505
Application Date
20240112

Claims (5)

  1. 1. The flash heat treatment process of the ultra-high strength steel plate is characterized in that the ultra-high strength steel is smelted and forged to obtain a forging stock, hot rolled and then rapidly cooled to room temperature, then heat treatment is carried out, the plate blank is firstly kept at 600-650 ℃ for 20-40 min, then the plate blank is heated to 900-950 ℃ by adopting the heating rate of 100-150 ℃ per second, is kept at the temperature for 5-15 s and then is cooled to the room temperature at the rate of 50-100 ℃ per second, and finally is kept at the temperature of 150-250 ℃ for 60-120 min, so that the ultra-high strength steel plate can be obtained; The ultra-high strength steel plate comprises the following chemical components in percentage by mass ：C：0.25～0.35％、Si：0.3～1.5％、Mn：2.0～2.5％、Ni：0.4～0.6％、Cr：0.3～0.8％、Mo：0.1～0.5％、Al：0.01～0.04％、B：0.0015～0.0020％、Nb：0.02～0.05％、Ti：0.005～0.020％、N≤0.003％、S≤0.010％、P≤0.010％; and the balance of Fe and other unavoidable impurities; The final structure of the ultra-high strength steel plate is tempered martensite, nano precipitated carbide and film-shaped residual austenite, the size of the precipitated carbide is 20-100 nm, the film-shaped residual austenite is positioned between martensite laths, the width is 5-40 nm, and the grain size is 11-12 levels.
  2. 2. The heat treatment process according to claim 1, wherein the ultra-high strength steel smelting and forging is characterized in that raw materials are smelted by a vacuum induction furnace, casting is performed after smelting, a casting blank is forged into 80mm square billets after riser heads are cut off, the forging temperature is less than or equal to 1150 ℃, and the final forging temperature is less than or equal to 900 ℃, so that a forging blank is obtained.
  3. 3. The heat treatment process according to claim 1, wherein the rapid cooling to room temperature after hot rolling is performed by carrying out homogenization treatment on a forging stock at 1150-1200 ℃ for 60-120 min, removing surface oxide scales after tapping, carrying out two-stage rolling, wherein the initial rolling temperature of rough rolling is 1100-1150 ℃, the temperature to be heated is more than or equal to 960 ℃, the initial rolling temperature of finish rolling is 920-880 ℃, the final rolling temperature is more than or equal to 840 ℃, and rapidly cooling to room temperature after rolling.
  4. 4. The heat treatment process according to claim 1, wherein the yield strength (R p0.2 ) of the ultra-high strength steel plate is not less than 1100MPa, the tensile strength (R m ) is not less than 1200MPa, the elongation (A) is not less than 12%, and the impact toughness value at-40 ℃ is not less than 70J.
  5. 5. The heat treatment process according to claim 1, wherein the thickness of the ultra-high strength steel plate is 10-30 mm.

Description

Flash heat treatment process of ultra-high strength steel plate Technical Field The invention belongs to the field of metal materials, and particularly relates to a flash heat treatment process of an ultra-high strength steel plate. Background At present, few enterprises can produce ultra-high strength steel with the yield strength of 1100MPa, ultra-high strength steel plates have wide market prospect, the ultra-high strength steel plates are generally produced by using an off-line/on-line quenching and tempering (Q-T/DQ-T) heat treatment process, the steel plates have high strength and certain plasticity in low-temperature tempering, but the low-temperature impact toughness is insufficient, the steel plates cannot be applied to special scenes such as low-temperature severe cold, the toughness is improved to some extent in high-temperature tempering, the strength is greatly reduced, the energy consumption generated by high-temperature long-time tempering is high, and on the premise of not greatly increasing the cost, the steel plates have good low-temperature impact toughness on the premise of ensuring the strength and the plasticity is the problem to be solved at present. The invention patent CN108315671A provides a preparation method of low yield ratio ultra-high strength steel with yield strength of 1000MPa, and the invention adopts an off-line quenching and low temperature tempering process to prepare Q1000 ultra-high strength steel with lower strength and only considers the impact toughness value of minus 20 ℃, and meanwhile, the process flow is long, and the production efficiency is reduced. The invention patent CN100372962C provides an ultra-high strength steel plate with the yield strength of over 1100MPa and a manufacturing method thereof, and the invention utilizes a heat treatment process of TMCP+on-line quenching and tempering at 350-750 ℃ to manufacture the Q1100 ultra-high strength steel plate with the thickness of 16-25 mm, and the impact toughness value at-40 ℃ is less than or equal to 40J. The invention patent CN114196879B provides a structural steel plate with 1000 MPa-grade yield strength and a manufacturing method thereof, wherein the structural steel plate is manufactured by adopting a quenching and tempering process, has the yield strength of more than or equal to 1065MPa, the tensile strength of more than or equal to 1166MPa, the elongation after fracture of more than or equal to 18.5 percent, and the impact energy of-85 ℃ of more than or equal to 106J, which is 15-40 mm thick and ultrahigh-strength plate, but is added with a large amount of precious alloy elements, such as 10.0-15.0 percent of Ni element, 0.80-1.50 percent of Mo element and the like, so that the cost is greatly increased, and the structural steel plate is not suitable for industrial production. The invention patent CN115537508A provides a flash heat treatment method of a high-strength steel plate, which replaces the traditional long-time tempering process by using a flash heat treatment technology on the basis of ensuring mechanical properties, improves production efficiency, realizes energy conservation and emission reduction, but the thickness of the steel plate is only 5mm, and does not consider the influence of the flash heat treatment method on low-temperature impact toughness. Disclosure of Invention The invention mainly aims at the problems that the traditional Q-T and DQ-T heat treatment processes cannot achieve both strength and low-temperature toughness in low-temperature tempering, and the strength is reduced and the energy consumption is increased in high-temperature tempering, and provides a flash heat treatment process for ultra-high strength steel, which can replace the traditional quenching and tempering process, improve the low-temperature toughness on the basis of ensuring the strength and the plasticity, simultaneously reduce the energy consumption, realize energy conservation and emission reduction, and improve the production efficiency. In order to achieve the above purpose, the invention adopts the following technical scheme: The invention discloses a flash heat treatment process for an ultra-high strength steel plate, which comprises the steps of smelting and forging the ultra-high strength steel to obtain a forging stock, hot rolling the forging stock, rapidly cooling the forging stock to room temperature, carrying out heat treatment, preserving heat of a plate blank at 600-650 ℃ for 20-40 min, heating the plate blank to 900-950 ℃ by adopting a heating rate of 100-150 ℃ per second, preserving heat for 5-15 s, cooling the plate blank to the room temperature at a rate of 50-100 ℃ per second, and preserving heat at 150-250 ℃ for 60-120 min to obtain the ultra-high strength steel plate with good toughness matching. Further, the ultra-high strength steel plate comprises the following chemical components in percentage by mass ：C：0.25～0.35％、Si：0.3～1.5％、Mn：2.0～2.5％、Ni：0.4～0.6％、Cr：0.3～0.8％、Mo：0.1～0.5％、