600 MPa-grade highly-chambered steel plate for automotive chassis and manufacturing method thereof

Abstract

The invention provides a 600 MPa-grade highly-chambered steel plate for automotive chassis. Steel of the steel plate is composed of, in percentage by weight, 0.04-0.10% of C, Si smaller than 0.70%, 1.0-1.6% of Mn, 0.02-0.08% of Als, 0.01-0.05% of Nb, P smaller than 0.015%, S smaller than 0.005% and the balance Fe and inevitable impurities. The invention further provides a manufacturing method of the steel plate. The method comprises the steps of heating continuous casting sheet billets with the thickness ranging from 80 mm to 230 mm to 1220+ / -20 DEG C, and preserving the temperature for 1.8-3 hours; carrying out two-stage rolling, wherein the rolling temperature of the recrystallizing region is higher than 1050 DEG C, the thickness of intermediate billets ranges from 35 mm to 60 mm, the finish rolling temperature of the non-recrystallizing region ranges from 840 DEG C to 920 DEG C, and the thickness of finished products ranges from 2.0 mm to 6.0 mm; carrying out continuous laminar flow cooling after finish rolling, wherein the cooling rate is 20-40 DEG C / s and the coiling temperature ranges from 450 DEG C to 580 DEG C. According to the invention, the steel plate is high in alloy content and low in cost, the hot rolling process is simple, the rolling performance of the steel plate is uniform, and the matching performance between the strength and the hole chambering rate is good.

Description

technical field [0001] The invention belongs to the field of steel rolling, and in particular relates to a hot-rolled high-hole expansion steel plate produced on a CSP continuous rolling line with a tensile strength reaching 600 MPa and a manufacturing method thereof. Background technique [0002] In recent years, with the rapid development of the automobile industry, automobiles have increasingly strict requirements on steel materials. While the strength requirements for steel materials have been increased, it is also necessary to ensure the machinability of steel under high-strength conditions, and at the same time meet the requirements of various industries. Special requirements for processing performance of auto parts. As an important part of the vehicle, automobile chassis parts have complex shapes and require forming methods including stretching, bending, and hole expansion during the manufacturing process. higher requirements. Under such conditions, hot-rolled high-...

AI Technical Summary

Problems solved by technology

The disadvantage is that the hot rolling process, especially the cooling process, is complex and difficult to control accurately, which is not conducive to obtaining stable steel plates on the continuous casting and rolling production line.

[0005] "A Hot Rolled High Hole Expanding Steel" (JP2006063394) discloses that the carbon content of the high hole expanding steel is 0.2-0.48%, and the tensile strength is greater than 440MPa. The disadvantage is that the hole expanding rate is only higher than 70%. And after hot rolling, it needs to be annealed at 640°C

[0006] "A 780MPa-grade hot-rolled high-hole-expanding steel" (US2006096678), the microstructure of the disclosed high-hole-expanding steel plate is composed of ferrite and bainite, the tensile strength reaches 780MPa, and the hole expansion rate is ≥ 60% , but the composition of the steel plate contains a certain amount of precious metal molybdenum, and the cost is relatively high

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