980 MPa-grade hot-rolled high-strength high-hole-expansion-ratio steel and manufacturing method thereof

Abstract

The invention provides 980 MPa-grade hot-rolled high-strength high-hole-expansion-ratio steel and a manufacturing method thereof. The 980 MPa-grade hot-rolled high-strength high-hole-expansion-ratio steel comprises, by weight, 0.05%-0.10% of C, 0.1%-0.8% of Si, 1.5% -2.5% of Mn, 0-0.015% of P, 0-0.005% of S, 0-0.003% of O, 0.02%-0.08% of Al, 0-0.005% of N, 0.05%-0.15% of Ti, 0.02%-0.06% of Nb, 0.1%-1.0% of Cr, 0.01%-0.10% of V, and the balance Fe and inevitable impurities, wherein the chemical components meet the relations that 0.15%<=Nb+Ti+V<=0.25%, and 0.01%<=(Ti-3.42N) / 4+V / 4.24<=0.06%. The microstructure of the steel is made of granular bainite and martensite; the yield strength of the steel is equal to or higher than 900 MPa, the tensile strength of the steel is equal to or higher than 980 MPa, the ductility of the steel is equal to or higher than 15%, and the hole expansion ratio of the steel is equal or higher than 50%; and the 980 MPa-grade hot-rolled high-strength high-hole-expansion-ratio steel has excellent strength, ductility and hole expansion matching and can be widely applied to thinned high-strength complexly-formed components such as an automobile chassis, a crossbeam and a wheel.

Description

technical field [0001] The invention belongs to the field of hot-rolled high-strength steel, and in particular relates to a 980MPa grade hot-rolled high-strength high-hole expansion steel and a manufacturing method thereof. Background technique [0002] With the increasingly stringent national environmental protection laws and regulations and the implementation of the country's restrictions on automobile emissions, in the field of automobiles, especially passenger cars, high-strength thinning or lightweight automobile structures have become an important research direction for major international automobile manufacturers. However, unlike the high-strength thinning and lightweight trends of passenger cars, the lightweight work of commercial vehicles has not formed a trend. On the one hand, due to the serious overloading of commercial vehicles, the designers of commercial vehicles have a large design margin for the structure; at the same time, the commercial vehicles themselves...

AI Technical Summary

Problems solved by technology

This is because, if the steel composition and process design ideas remain unchanged, it is difficult to greatly improve its final mechanical properties.

Judging from the literature at home and abroad, there is no 980MPa hot-rolled ultra-high-strength steel with high strength, high plasticity and high hole expansion performance, and there is no mass-produced product available.

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