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CN-122013038-A - Ultrahigh-strength high-toughness steel plate and preparation method thereof

CN122013038ACN 122013038 ACN122013038 ACN 122013038ACN-122013038-A

Abstract

The invention relates to an ultrahigh-strength high-toughness steel plate and a preparation method thereof, belongs to the technical field of ultrahigh-strength steel plates, and solves the problems of lower toughness and higher cost of steel plates with strength of more than 2000MPa in the prior art. The steel plate comprises ：C 0.34-0.40%,Si 0.20-0.50%,Mn 0.30-0.50%,P≤0.008%,S≤0.002%,Cr 0.6-1.2%,Ni 0.6-1.2%,Mo 0.20-0.40%,Ti 0.010-0.020%,Nb 0.03-0.07%,Al 0.02-0.05%,N≤0.0040%,B 0.001-0.004%, percent of Fe and unavoidable impurities by mass, wherein the steel plate comprises a microstructure of martensite matrix by regulating and controlling the types and the proportions of the components, so that the strength of the steel plate is improved, and meanwhile, MC-type carbide (such as TiC, nbC, (Ti, mo) C) precipitation strengthening phases are formed by regulating and controlling the content of elements C, ti, nb, mo, N, martensite grains are refined, the toughness of the steel is improved, the strength of the steel plate is higher than 2000MPa, the steel plate has excellent toughness and lower cost, and the popularization and the application of the high-strength steel can be promoted.

Inventors

  • WEI WENCHAO
  • SHI JIE
  • YAN YONGMING
  • WANG MAOQIU
  • LI XIAOYUAN
  • XU LE
  • HE XIAOFEI

Assignees

  • 钢铁研究总院有限公司

Dates

Publication Date
20260512
Application Date
20260129

Claims (10)

  1. 1. The ultra-high strength high toughness steel plate is characterized in that the steel plate comprises ：C 0.34-0.40%,Si 0.20-0.50%,Mn 0.30-0.50%,P ≤0.008%,S ≤0.002%,Cr 0.6-1.2%,Ni 0.6-1.2%,Mo 0.20-0.40%,Ti 0.010-0.020%,Nb 0.03-0.07%,Al 0.02-0.05%,N ≤0.0040%,B 0.001-0.004%, of Fe and unavoidable impurities according to mass percentage.
  2. 2. The steel sheet according to claim 1, wherein the constituent elements of the steel sheet include ：C 0.34-0.40%,Si 0.22-0.38%,Mn 0.31-0.48%,P ≤0.008%,S ≤0.002%,Cr 0.65-1.15%,Ni 0.6-1.2%,Mo 0.20-0.35%,Ti 0.01-0.020%,Nb 0.03-0.07%,Al 0.02-0.028%,N ≤0.0040%,B 0.0015-0.0031%, the balance Fe and unavoidable impurities in terms of mass percent.
  3. 3. The steel sheet according to claim 1, wherein the contents of the elements Ti, nb, N in the steel sheet satisfy the following relationship that 3.5 N≤Ti≤5.0N, nb+Ti-3.5 N≤0.04%.
  4. 4. The steel sheet according to claim 1, wherein the prior austenite grain size of the steel sheet microstructure is 6 μm or less.
  5. 5. The steel sheet of claim 1, wherein the steel sheet microstructure comprises a martensitic matrix, austenite, and a precipitated phase, wherein the precipitated phase comprises nano-sized TiC, nbC, (Ti, mo) C, (Nb, mo) C precipitated phases.
  6. 6. A method of producing the ultra-high strength high toughness steel sheet according to any one of claims 1 to 5, characterized in that the method comprises: (1) Smelting, refining outside the furnace, vacuum degassing and casting the raw materials in sequence according to the target component content of the steel plate to obtain a casting blank; (2) Forging the casting blank to obtain a plate blank; (3) And heating, preserving heat, rolling, quenching and tempering the slab in sequence.
  7. 7. The method of claim 6, wherein in step (1), the casting is followed by an electroslag remelting process.
  8. 8. The method according to claim 6, wherein in the step (3), the heating and maintaining temperature is 1280-1320 ℃ and time is 1-1.5min/mm.
  9. 9. The method according to claim 6, wherein in the step (3), the rolling includes a rough rolling stage and a finish rolling stage, the rough rolling stage has a temperature of 1050 to 1200 ℃ and a total compression ratio of 65 to 75%, the finish rolling stage has a primary rolling temperature of 950 to 980 ℃ and a finish rolling temperature of 800 to 850 ℃ and a total compression ratio of 25 to 35%.
  10. 10. The method according to claim 6, wherein in the step (3), the quenching is performed by maintaining the temperature at 880-920 ℃ for 2.0-3.0min/mm and cooling to room temperature at a speed of 100 ℃ or more.

Description

Ultrahigh-strength high-toughness steel plate and preparation method thereof Technical Field The invention relates to the technical field of ultrahigh-strength steel plates, in particular to an ultrahigh-strength high-toughness steel plate and a preparation method thereof. Background Ultra-high strength steel sheets are widely used in the automotive, mechanical and equipment manufacturing fields. With the continuous improvement of energy saving and emission reduction requirements, the use of a steel plate with higher strength to improve the light weight level and bearing capacity of vehicle equipment is one of the main development trends. The ultra-high strength steel plates mainly used at present mainly comprise wear-resistant steel (NM 450, NM500 and the like) and hot forming steel (MS 1500, MS1800 and the like), the strength reaches 1500MPa-1800MPa, and the ultra-high strength steel plates with higher strength are less in application. The ultra-high strength steel plate applied to the fields of automobiles and machinery is mainly made of medium-low alloy steel by adopting the industrialized flow of converter, continuous casting and continuous rolling, and then a low-temperature tempered martensite structure is obtained by quenching and low-temperature tempering, so that the high strength is obtained, and meanwhile, the toughness is better, however, when the strength of the steel plate reaches more than 2000MPa, the toughness requirement of the steel plate is difficult to meet by the process route. The ultra-high strength steel such as 300M, aermet and 100 adopts a medium-high alloy component system and is matched with advanced special smelting processes such as vacuum consumable and the like, so that the high strength and high toughness of the material are realized, but the comprehensive cost of the material is too high, and the application field is limited. Therefore, a steel plate with both ultra-high strength and high toughness and a preparation method thereof are needed to balance the mechanical properties and cost of the ultra-high strength steel plate and promote popularization and application. Disclosure of Invention In view of the above analysis, the embodiment of the invention aims to provide an ultra-high strength and high toughness steel plate and a preparation method thereof, so as to solve at least one of the problems of lower toughness and higher cost of the steel plate with tensile strength larger than 2000MPa in the prior art. On one hand, the embodiment of the invention provides an ultra-high strength high toughness steel plate, which comprises the following components in percentage by mass, wherein the balance of ：C 0.34-0.40%,Si 0.20-0.50%,Mn 0.30-0.50%,P ≤0.008%,S ≤0.002%,Cr 0.6-1.2%,Ni 0.6-1.2%,Mo 0.20-0.40%,Ti 0.010-0.020%,Nb 0.03-0.07%,Al 0.02-0.05%,N ≤0.0040% ,B 0.001-0.004%, is Fe and unavoidable impurities. Further, the steel plate comprises ：C 0.34-0.40%,Si 0.22-0.38%,Mn 0.31-0.48%,P ≤0.008%,S ≤0.002%,Cr 0.65-1.15%,Ni 0.6-1.2%,Mo 0.20-0.35%,Ti 0.01-0.020%,Nb 0.03-0.07%,Al 0.02-0.028%,N ≤0.0040%,B 0.0015-0.0031%, parts by mass of Fe and unavoidable impurities. Furthermore, the contents of Ti, nb and N in the steel plate satisfy the following relation that Ti is more than or equal to 3.5N and less than or equal to 5.0N, and Nb+Ti-3.5N is more than or equal to 0.04%. Further, the prior austenite grain size of the microstructure of the steel sheet is 6 μm or less. Further, the steel plate microstructure comprises a martensitic matrix, austenite and a precipitation strengthening phase. Further, the precipitated phase includes nano TiC, nbC, (Ti, mo) C, (Nb, mo) C, and a precipitated phase. In another aspect, the embodiment of the invention also provides a method for preparing the ultra-high strength and high toughness steel plate, which comprises the following steps: (1) Weighing raw materials according to the target component content of the steel plate, and sequentially carrying out smelting, external refining, vacuum degassing and casting to obtain a casting blank; (2) Forging the casting blank to obtain a plate blank; (3) And heating, preserving heat, rolling, quenching and tempering the slab in sequence. Further, in the step (1), an electroslag remelting process is further included after casting. Further, in the step (2), the forging total compression ratio is 3 to 6 times. Further, in the step (3), the heating and heat preservation temperature is 1280-1320 ℃ and the time is 1-1.5min/mm. Further, in the step (3), the rolling comprises a rough rolling stage and a finish rolling stage, wherein the temperature of the rough rolling stage is 1050-1200 ℃, the total compression ratio is 65-75%, the initial rolling temperature of the finish rolling stage is 950-980 ℃, the final rolling temperature is 800-850 ℃, and the total compression ratio is 25-35%. Further, in the step (3), the specific process of quenching is that the quenching is carried out at the temperature of 880-920 ℃ for 2.