Super-high-strength hot-rolled steel plate and steel belt with good fatigue and broaching performance and manufacturing method of steel plate and steel belt

Abstract

The invention relates to a super-high-strength hot-rolled steel plate and steel belt with good fatigue and broaching performance and a manufacturing method of the steel plate and steel belt. The steelplate and steel belt are prepared from, by weight, 0.07-0.14% of C, 0.1-0.4% of Si, 1.55-2.00% of Mn, smaller than or equal to 0.015% of P, smaller than or equal to 0.004% of S, 0.01-0.05% of Al, smaller than or equal to 0.005% of N, 0.15-0.50% of Cr, 0.1-0.35% of V, 0.01-0.06% of Nb, 0.15-0.50% of Mo, smaller than or equal to 0.02% of Ti and the balance Fe and unavoidable impurities. Meanwhile,the condition 1.0<=[(Cr / 52) / (C / 4)+(Nb / 93+Ti / 48+V / 51+Mo / 96) / (C / 12)]<=1.6 needs to be met. For the super-high-strength hot-rolled steel plate and steel belt, the tensile strength is greater than or equal to 780 MPa, the yield strength is greater than or equal to 660 MPa, the tensile fatigue limit (circulation of 10,000,000 times) FL is greater than or equal to 570 MPa, or the ratio of the fatigue limit to the tensile strength FL / Rm is greater than or equal to 0.72, and the broaching rate meets the conditions that if an original hole is a punched hole, the broaching rate is greater than 85%; if the original hole is a reamed hole, the broaching rate is greater than 120%.

Description

technical field [0001] The invention belongs to the field of metal materials, and specifically relates to an ultra-high-strength hot-rolled steel plate and steel strip with good fatigue and hole expansion properties and a manufacturing method thereof, which are mainly used in the manufacture of automobile chassis, suspension parts and other products. Background technique [0002] The "light weight" of automobiles can directly reduce emissions and fuel consumption, which is the goal of the development of today's automobile manufacturing industry. An important measure of automobile "lightweight" is to use high-strength and ultra-high-strength steel plates instead of mild steel. After a large number of high-strength steels are used, a 20-25% weight reduction effect can be achieved. In the past ten years, advanced high-strength steel with high strength and high elongation has been widely used in body-in-white structural parts to achieve "lightweight", and excellent energy-savin...

AI Technical Summary

Problems solved by technology

However, the large amount of carbide precipitation and coarsening will greatly damage the hole expansion performance of the material.

In addition, generally speaking, the higher the yield strength of the material, the higher the fatigue limit of the material; however, for this type of material, the improvement of the yield strength greatly depends on the large amount of carbide precipitation, but the large amount of carbide precipitation is the same as coarsening Will greatly reduce the fatigue limit of this type of material

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