900 MPa-grade hot-rolled nanometer precipitation strengthening type high-strength high-toughness steel and manufacturing method thereof

Abstract

The invention discloses 900 MPa-grade hot-rolled nanometer precipitation strengthening type high-strength high-toughness steel and a manufacturing method thereof. The chemical components of the steelcomprise, by weight, greater than or equal to 0.10% and less than or equal to 0.20% of C, greater than or equal to 1.0% and less than or equal to 2.0% of Mn, less than or equal to 0.015% of P, less than or equal to 0.005% of S, greater than or equal to 0.02% and less than or equal to 0.08% of Al, less than or equal to 0.005% of N, greater than or equal to 0.02% and less than or equal to 0.05% of Nb, greater than or equal to 0.10% and less than or equal to 0.20% of Ti, greater than or equal to 0.20% and less than or equal to 0.50% of Mo, greater than or equal to 0.10% and less than or equal to0.50% of V, less than or equal to 0.003% of O, and the balance Fe and inevitable impurities, wherein the elements simultaneously meet the requirement that Nb / 7.74+(Ti-3.42N) / 4+Mo / 8+V / 4.24 is greater than or equal to 0.10% and less than or equal to 0.20%. According to the steel, the microstructure of the steel is bainite and a nanoscale carbide, the width of a bainite plate strip is 0.2-0.3 micron,the size of the nanoscale carbide is less than or equal to 10 nm, the yield strength is larger than or equal to 800 MPa, the tensile strength is larger than or equal to 900 MPa, the elongation percentage is larger than or equal to 14%, the impact energy of -40 DEG C is larger than or equal to 50J, and the steel shows excellent strength, plasticity and toughness matching.

Description

technical field [0001] The invention belongs to the field of hot-rolled high-strength steel, and in particular relates to a 900MPa grade hot-rolled nano-precipitation strengthened high-strength and high-toughness 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 international automobile manufacturers. In addition to thinning high-strength steel, advanced materials such as lighter magnesium, aluminum and even carbon fiber are also used. 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, because commercial vehicles...

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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.

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