CN-122013036-A - TMCP state high-strength steel plate and production process thereof

Abstract

The invention discloses a TMCP state high-strength steel plate and a production process thereof, and belongs to the technical field of high-strength steel manufacture. The steel plate comprises the chemical components of ：C：0.06-0.10%,Si：0.15-0.3%,Mn：1.2-2.0%,Cr：0.15-0.25%,Ni：0.15-0.25%,Mo：0.1-0.2%,Nb+Ti+B≤0.1%,P≤0.025%,S≤0.015%, percent by weight of Fe and impurities, and forms a structure with fine-grain bainite (grain size is less than or equal to 5 mu m) as a main component through two-stage large-pressure rolling (the rough rolling reduction rate is more than or equal to 65 percent, the finish rolling is more than or equal to 70 percent) and dynamic cooling control (the water inlet temperature is 780-820 ℃, the cooling speed is more than or equal to 20 ℃ per second, the reddening temperature is 450-480 ℃, the yield strength is more than or equal to 850MPa, the tensile strength is more than or equal to 950MPa, the elongation after break A50 is more than or equal to 22 percent, the longitudinal impact power is more than or equal to 200J, the alloy cost is reduced by more than 25 percent, and the technological process is shortened by 30 percent.

Inventors

• FENG BIN
• LI CHENXIAO
• Yang Kangshuai
• WANG GUOJI
• HUANG JUN
• JIAO WEICHAO
• HOU MEILING
• XIAO QIANGJIAN

Assignees

• 江阴兴澄特种钢铁有限公司

Dates

Publication Date

20260512

Application Date

20260122

Claims (5)

1. 1. A TMCP state high-strength steel plate is characterized by comprising the following chemical components in percentage by weight, wherein the balance of ：C：0.06-0.10%,Si：0.15-0.3%,Mn：1.2-2.0%,Cr：0.15-0.25%,Ni：0.15-0.25%,Mo：0.1-0.2%,Nb+Ti+B≤0.1%,P≤0.025%,S≤0.015%, is Fe and unavoidable impurities, and the carbon equivalent CEV of the high-strength steel plate is less than or equal to 0.41%.
2. 2. The TMCP state high-strength steel plate according to claim 1, wherein the mechanical property indexes are that the yield strength Re is more than or equal to 850MPa, the tensile strength Rm is more than or equal to 950MPa, the elongation after break A50 is more than or equal to 22%, the longitudinal impact power KV2 at-40 ℃ is more than or equal to 200J, and the transverse and longitudinal cold bending property meets d=2a (180 ℃ is qualified).
3. 3. The TMCP state high strength steel sheet according to claim 1, wherein the microstructure is mainly fine-grained bainite, the grain size of the fine-grained bainite is 3-5 μm, the ratio is 80-90%, M/a islands with the size of 1 μm or less are distributed among bainitic laths, a dual-phase structure of the fine-grained bainite and the M/a islands is formed, and the width of the bainitic laths is 0.2 μm or less.
4. 4. A production process of TMCP state high-strength steel, which is used for preparing the TMCP state high-strength steel plate according to any one of claims 1-3, and is characterized by comprising four procedures of continuous casting billet heating, controlled rolling, controlled cooling and air cooling after rolling, and specifically comprises the following steps: Step 1, continuously casting blanks are heated, namely continuously casting blanks with the thickness of 150mm are selected, the heating time is more than or equal to 240min, the average temperature of soaking sections is more than or equal to 1200 ℃, and the surface temperature of the casting blanks is more than or equal to 1150 ℃ when the heating is finished; The rolling is controlled to be divided into two stages of rough rolling and finish rolling, wherein the initial rolling temperature of the rough rolling is more than or equal to 1000 ℃, 8-pass rolling is carried out, the single-pass rolling reduction is more than or equal to 5%, the accumulated rolling reduction is more than or equal to 65%, the thickness of the rough rolled steel plate at the temperature is 3-4 times that of the finished steel plate, the initial rolling temperature of the finish rolling is 960-980 ℃, the final rolling temperature is more than or equal to 850 ℃, and the accumulated rolling reduction is more than or equal to 70%; controlling cooling, namely controlling cooling process by adopting ACC, wherein the water inlet temperature is 780-820 ℃, the cooling speed is more than or equal to 20 ℃ per second, and the reddish temperature is 450-480 ℃, wherein the difference delta T between the reddish temperature and the water inlet temperature is 300-350 ℃; and step 4, air cooling after rolling, namely naturally air cooling to room temperature after controlled cooling is finished.
5. 5. The production process of TMCP state high-strength steel as claimed in claim 4, wherein the thickness of the finished steel plate is 20-50 mm.

Description

TMCP state high-strength steel plate and production process thereof Technical Field The invention relates to the technical field of high-strength steel manufacturing, in particular to a TMCP state high-strength steel plate with short flow, low cost and ultrahigh toughness plastic matching property and a production process thereof, which are suitable for the fields of engineering machinery, heavy equipment and the like with strict requirements on steel strength, toughness and weldability. Background With the development of modern industrial technology, high-strength structural steel with high strength, high toughness and excellent plasticity and weldability is increasingly widely applied to the field of engineering machinery. With the application of the high-strength structural steel, the production efficiency of the manufacturing industry is improved, the dead weight of engineering mechanical equipment is reduced, and the energy consumption is effectively reduced. The wide application causes the great improvement of the demand, but the traditional manufacturing method can not always consider the relationship between the low cost and the high performance of the short process. Through reasonable alloy composition design, the TMCP process is adopted, the production process flow is shortened, the cost is reduced, the high strength of the steel plate is ensured, and meanwhile, the plasticity and the toughness are well matched, so that the production of the high-grade mechanical steel is realized. The publication No. CN 113106333A provides a low-cost high-strength steel with yield strength of 800Mpa and a production method thereof, and the high-strength steel with yield strength of more than 800Mpa, tensile strength of more than 840Mpa, elongation of more than 13 percent and 20 ℃ impact energy of more than 150J is obtained by controlling cooling and offline tempering, and the high-strength steel has good toughness matching, but longer process flow, relatively higher cost and poorer plasticity. The publication No. CN 111647813B provides TMCP process high-strength steel with yield strength of >800Mpa and a production method, grains are refined through TMCP+three-stage cooling process, so that the high-strength steel with yield strength of >800Mpa, tensile strength of >850Mpa, elongation of >20 percent and impact energy of-20 ℃ of >47J is obtained, high strength is realized, good elongation is obtained, off-line heat treatment after rolling is omitted, but the process flow is relatively longer, and the low-temperature impact toughness is relatively poor. The publication No. CN 114959515A provides 890Mpa low in cold crack sensitivity coefficient, high-strength steel and a production method, alloy with higher cost is not needed to be added in production, meanwhile, the technological process is reduced in a cold control mode, and the high-strength steel with yield strength of equal to or more than 890Mpa, tensile strength of equal to or more than 940Mpa, elongation of equal to or more than 11%, and longitudinal impact energy of-20 ℃ of equal to or more than 100J is obtained, the alloy cost is lower, the technological process is shorter, the cost is lower, and the plasticity is poorer at the same time of high strength. Therefore, developing TMCP state high-strength steel with short process flow, low alloy cost, high strength, high toughness, high plasticity and excellent weldability becomes a technical problem to be solved in the field. Disclosure of Invention The invention aims to solve the technical problems of providing a TMCP state high-strength steel plate and a manufacturing method thereof aiming at the prior art, wherein the method has the advantages of lower alloy cost, shorter production process flow and lower overall production cost, and ultra-high strength steel with tensile strength of more than 850Mpa and excellent low-temperature impact toughness is obtained through the TMCP process. The technical scheme adopted by the invention for solving the problems is that the TMCP state high-strength steel plate comprises the following chemical components in percentage by weight C：0.06-0.10%,Si：0.15-0.3%,Mn：1.2-2.0%,Cr：0.15-0.25%,Ni：0.15-0.25%,Mo：0.1-0.2%,Nb+Ti+B≤0.1%,P≤0.025%,S≤0.015%, and the balance of Fe and unavoidable impurities, wherein the carbon equivalent CEV is less than or equal to 0.41 percent. The design basis and main functions of each chemical element are as follows: C, controlling the content of the carbon atoms to be 0.06-0.10%, not only improving the strength of the steel through solid solution strengthening, but also ensuring the carbon equivalent CEV to be less than or equal to 0.41%, avoiding the risk of welding cold cracks caused by overhigh carbon content, and balancing the strength and the weldability; si is 0.15-0.3%, austenite grain coarsening can be restrained, high-temperature stability of the steel is improved, and meanwhile, deoxidization effect of the steel is improved; mn is 1.2-2.0%,