Search

CN-121976120-A - 900 MPa-level heat-treated steel plate, preparation method and application

CN121976120ACN 121976120 ACN121976120 ACN 121976120ACN-121976120-A

Abstract

The invention provides a 900 MPa-level heat-treated steel plate, a preparation method and application. A900 MPa-level heat-treated steel plate comprises the following chemical components ：C：0.17%～0.22%,Si：0.20%～0.40%,Mn：1.3%～1.6%,P≤0.020%,S≤0.003%,Ti：0.06%～0.10%,N≤0.006%,B：0.0010%～0.0020%; in percentage by mass, wherein the steel plate does not contain Mo, V, nb and Cr, and the thickness of the steel plate is 30-35 mm. The invention provides high-strength heat-treated steel with high strength, good elongation and excellent toughness, a preparation method and application thereof, and a structural member, and the addition amount of molybdenum (Mo), vanadium (V), niobium (Nb) and chromium (Cr) elements can be reduced.

Inventors

  • XU BO
  • GUO QINGXIAN
  • LIANG LIANG
  • LIANG WEN
  • ZHANG HEXIONG
  • ZHOU JIANFENG
  • HUANG XIAOFENG
  • CHEN MINGRUI
  • Tan Dajin

Assignees

  • 湖南华菱涟钢特种新材料有限公司
  • 湖南华菱涟源钢铁有限公司

Dates

Publication Date
20260505
Application Date
20260209

Claims (10)

  1. 1. A900 MPa grade heat treatment steel plate is characterized by comprising the following chemical components, by mass, 0.17% -0.22% of C, 0.20% -0.40% of Si, 1.3% -1.6% of Mn, less than or equal to 0.020% of P, S ≤ 0.003%,Ti:0.06%~0.10%,N ≤ 0.006%,B:0.0010%~0.0020%; The steel sheet does not contain Mo, V, nb, and Cr; The thickness of the steel plate is 30 mm-35 mm.
  2. 2. The 900 MPa-level heat-treated steel sheet according to claim 1, wherein the Ti content is 0.07% -0.09% and the B content is 0.0012% -0.0018% by mass.
  3. 3. A method of producing 900 MPa-grade heat-treated steel sheet according to claim 1 or 2, comprising the steps of: A1, smelting and casting the 900 MPa-level heat-treated steel plate preparation raw material to prepare an alloy plate blank; a2, performing heating treatment, rolling treatment, cooling treatment, coiling treatment and slow cooling treatment on the alloy plate blank to obtain a high-strength hot rolled steel coil; a3, carrying out transverse cutting and leveling treatment, quenching treatment and tempering treatment on the high-strength hot rolled steel coil to obtain a high-strength heat-treated steel plate finished product; The quenching treatment conditions are 890-910 ℃, and the heat preservation is carried out for 65-75 min; The tempering treatment condition is 420-440 ℃, and the heat preservation time is 110-130 min.
  4. 4. A method for producing 900MPa grade heat treated steel sheet as claimed in claim 3 wherein the smelting process includes converter smelting, LF refining and vacuum degassing, Wherein the converter smelting step comprises the steps of adopting elements such as primary oxygen blowing decarburization, silicon, manganese and the like, adding active lime of 350+/-100 Kg for slag washing, adopting alloy or aluminum iron and the like for deoxidization alloying, and enabling the argon station temperature to be more than or equal to 1525 ℃.
  5. 5. The method for producing 900 MPa-level heat-treated steel sheet according to claim 3, wherein the casting process comprises a continuous casting process, wherein the superheat degree of the molten steel in the tundish is controlled to be 13-48 ℃, the corresponding continuous casting temperature is 1513-1548 ℃, and the withdrawal speed is not lower than 0.8 m/min.
  6. 6. A method for producing 900 MPa-grade heat-treated steel sheet according to claim 3, wherein the rolling process comprises rough rolling and finish rolling performed sequentially; the rough rolling comprises the steps of adopting 5-7 times of rolling, wherein the rolling reduction rate of the first time is more than or equal to 18%, the rolling reduction rate of the last time is more than or equal to 24%, the initial rolling temperature is 1200-1240 ℃, and the final cooling temperature is 1035-1085 ℃; the finishing rolling comprises the steps of adopting 7 frames for continuous rolling, wherein the descaling pressure of a finishing rolling inlet is more than or equal to 18MPa, the inlet temperature of the initial rolling is less than or equal to 1000 ℃, the final pass reduction rate is more than or equal to 10%, and the final cooling temperature is 845-875 ℃.
  7. 7. A method for producing 900 MPa-grade heat-treated steel sheet according to claim 3, wherein the cooling treatment comprises an ultra-fast cooling treatment and a layer cooling treatment performed in this order, the cooling rate of the ultra-fast cooling treatment is 80 ℃ to 200 ℃ per second, the cooling rate of the layer cooling treatment is not less than 15 ℃ per second, and the end temperature of the cooling treatment is 540 ℃ to 580 ℃.
  8. 8. A method of producing 900 MPa-grade heat treated steel sheet according to claim 3 wherein the transverse cut-to-flat process has an uncoiling temperature of less than or equal to 70 ℃.
  9. 9. A method of producing 900 MPa-grade heat treated steel sheet according to claim 3, wherein the target coiling temperature of the coiling treatment is 540 ℃ to 580 ℃, and the coiling temperatures of the head region and the tail region of the steel sheet are controlled to be 30 ℃ to 60 ℃ higher than the target coiling temperature, respectively, during the coiling.
  10. 10. A structural member, characterized in that the raw material for the manufacture of said structural member comprises 900 MPa-grade heat-treated steel sheet according to claim 1 or 2.

Description

900 MPa-level heat-treated steel plate, preparation method and application Technical Field The invention relates to the technical field of alloys, in particular to a 900 MPa-level heat-treated steel plate, a preparation method and application Background Steel materials are widely used in industrial fields due to their excellent mechanical properties, good workability and relatively low cost, and are especially dominant in the manufacture of structural members for large-scale industrial machinery (e.g., excavators, cranes, mining dump trucks, etc.). With the development of equipment to the large-scale, lightweight and high reliability, the performance requirements on structural steel are increasingly improved, and the structural steel not only needs to have high strength to bear complex loads, but also needs to have good elongation and excellent low-temperature toughness to ensure safe service under severe working conditions. At present, 900 MPa-grade high-strength steel has become a main material of key load-bearing structural members of large-scale engineering machinery. To achieve such high strength levels and to compromise plasticity and toughness, conventional techniques typically rely on the addition of certain amounts of microalloying elements and precious alloying elements, such as molybdenum (Mo), vanadium (V), niobium (Nb), and chromium (Cr). Wherein Mo and Cr can obviously improve the hardenability of steel, ensure uniform structure of thick section, and Nb and V effectively improve the strength through fine crystal strengthening and precipitation strengthening. However, the elements belong to strategic metals with higher prices and limited resources, and the large-scale use of the elements leads to the remarkable increase of the cost of raw materials, so that the economy and popularization potential of the 900 MPa-level high-strength steel in large-scale engineering application are severely restricted. Although the prior art has made a certain progress in the aspects of component design and rolling process, on the premise of not depending on Mo, V, nb, cr and other noble metal elements, how to enable the ultra-thick steel plate (such as more than 30 mm) to simultaneously meet the comprehensive performance indexes of yield strength of more than or equal to 900 MPa, elongation of more than or equal to 12 percent, impact energy of more than or equal to 60J at-20 ℃ and the like through a reasonable component system and a matched heat treatment process is still a technical problem which is not solved effectively in the field. Disclosure of Invention The invention mainly aims to provide a 900 MPa-level heat-treated steel plate, a preparation method and application thereof, and aims to provide high-strength heat-treated steel with high strength, good extensibility and excellent toughness, the preparation method and application thereof and a structural member, and the addition amount of molybdenum (Mo), vanadium (V), niobium (Nb) and chromium (Cr) elements can be reduced. In order to achieve the aim, the invention provides a 900MPa grade heat treatment steel plate which comprises the following chemical components in percentage by mass ：C：0.17%～0.22%,Si：0.20%～0.40%,Mn：1.3%～1.6%,P ≤ 0.020%,S ≤ 0.003%,Ti：0.06%～0.10%,N ≤ 0.006%,B：0.0010%～0.0020%; The steel sheet does not contain Mo, V, nb, and Cr; The thickness of the steel plate is 30 mm-35 mm. In the invention, carbon is an element with strength influence, the toughness of steel is influenced by too high or too low carbon content, silicon element plays a role in solid solution strengthening in steel, specific quantitative Si can effectively improve the strength of steel, but silicon also easily forms Fe 2SiO4 and forms eutectoid products with FeO on the surface of a steel billet, so that FeO is difficult to remove, the comprehensive performance of the steel is unfavorable, specific quantitative Mn is an effective element for improving the strength and toughness, the critical quenching speed of the steel can be reduced, austenite is stabilized, grains are thinned, pearlite transformation can be effectively delayed, the content is too high or too low, the high strength and toughness cannot be simultaneously realized, phosphorus easily generates center segregation, the formability is influenced, sulfur and nitrogen are easily combined with Ti in the steel, the strengthening effect of the Ti is influenced, meanwhile, the method belongs to unfavorable impurity factors, the titanium element has a certain fine crystal strengthening and precipitation strengthening effect, the element with larger strength increment performance is required, the boron element can be greatly increased when dissolved into the solid solution at high temperature, the yield performance can be improved, and the yield strength and the noble metal after the method is more economic than other metal. Therefore, iron element and other specific components are synergistic through a specific propo