A 900mpa hot-rolled nano-precipitation strengthened high-strength and high-toughness steel and its manufacturing method

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 specifically relates to a 900MPa-level hot-rolled nano-precipitation-strengthened high-strength high-toughness steel and a manufacturing method thereof. Background technique [0002] With the increasingly stringent national environmental protection laws and regulations and the country’s implementation of automobile emission restrictions, in the field of automobiles, especially passenger cars, high-strength thinning or lightweight automobile structure has 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 trend of high-strength thinning and lightweight of passenger cars, the lightweight work of commercial vehicles has not formed a trend. On the one hand, because commercial vehicles are generally ove...

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.

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