Hot rolled steel plate with yield strength being 700MPa and preparation method thereof

Abstract

The invention discloses a high-strength hot rolled steel plate with yield strength being 700MPa. The steel plate comprises the following chemical components by weight: 0.04-0.08% of C, 0.15-0.3% of Si, 1.20-1.90% of Mn, 0.020-0.060% of Al, not more than 0.015% of P, not more than 0.0009% of S, 0.06-0.08% of Nb, 0.09-0.12% of Ti, 0.0008-0.005% of B, not more than 0.002% of O and not more than 0.004% of N. A preparation method is characterized in that the heating temperature is 1240-1260 DEG C; the rough rolling temperature is 1230-1100 DEG C; the finish rolling inlet temperature is 1080-1040 DEG C; the final rolling temperature is 820-860 DEG C; the total finish rolling reduction ratio is not less than 85%; the laminar flow is cooled at a speed being not less than 60 DEG C / s after finish rolling; and the coiling temperature is controlled between 550 DEG C and 600 DEG C.

Description

technical field [0001] The invention relates to a cold-formed high-strength hot-rolled automotive structural metal material, in particular to a hot-rolled steel plate with a yield strength of 700 MPa or more and a preparation method thereof. Background technique [0002] The development and application of high-strength automotive steel plate materials is one of the main measures to realize the lightweight of automobiles. Generally, low-alloy high-strength steel mainly adopts ferrite + pearlite structure materials with single or composite addition of microalloying elements such as Nb, V, and Ti. As the strength increases, the formability of the material decreases, especially when the tensile strength reaches 700MPa, the cracking ratio of the stamped parts of the material is very high, and it is difficult to meet the forming requirements of mass production in automobile factories. Chinese patent 200610030713.8 discloses the production of 700MPa weather-resistant high-strength ...

AI Technical Summary

Problems solved by technology

[0002] The development and application of high-strength automotive steel plate materials is one of the main measures to realize the lightweight of automobiles. Generally, low-alloy high-strength steel mainly adopts ferrite + pearlite structure materials with single or composite addition of microalloying elements such as Nb, V, and Ti. As the strength increases, the formability of the material decreases, especially when the tensile strength reaches 700MPa, the cracking ratio of the stamping parts of the material is very high, and it is difficult to meet the forming requirements of the mass production of the automobile factory

Chinese patent 200610030713.8 discloses the production of 700MPa weather-resistant high-strength steel with Cu, Cr, Ni, Nb, Ti, Mo composite micro-alloying components, the content of alloy elements is high, and the production cost is high

Although the content of alloying elements is reduced, its yield strength can only reach 550-700MPa

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