A bake-hardening high-strength steel and its manufacturing method

Abstract

The invention discloses bake hardening type high-strength steel. The bake hardening type high-strength steel comprises, by mass percentage, 0.05 to 0.13% of C, 0.05 to 0.20% of Si, 0.50 to 1.50% of Mn, 0.02 to 0.06% of Al, larger than 0 and not larger than 0.0050% of N, and the balance iron and other inevitable impurities, and in addition, the condition that B-0.77*N is larger than or equal to 0.0005 and smaller than or equal to 0.0020% should be met. According to the bake hardening type high-strength steel, under the condition of not adding precious metals such as Mo, Cr, Ti and Nb, by controlling the mass percentage of carbon, manganese and boron, the technological processes and the technological parameters, the steel which is high in strength, low in cost, high in surface quality and of which the machining performance meets the requirements of automotive parts is manufactured.

Description

technical field [0001] The invention relates to a steel and a manufacturing method thereof, in particular to a high-strength steel and a manufacturing method thereof. Background technique [0002] The development of steel is high-strength, lightweight, and recyclable. With the development of new requirements for automotive materials, automotive materials have gradually developed from machinability to high-strength, bake-hardening and other new automotive materials. While the thickness of automotive materials is thinning, the strength requirements are also increased. However, excessive strength will bring difficulties to the manufacturing process of steel plates and stamping for users. Therefore, it is necessary to design an automotive material that can produce lower yield strength of steel plates so that For stamping parts, the yield strength increases during subsequent coating and baking, which meets the requirements of use. In the process of automobile lightweighting, the...

AI Technical Summary

Problems solved by technology

Ultra-low-carbon bake-hardening steel is realized on the basis of ultra-low-carbon steel by underalloying (adding less Nb, Ti and other alloys than IF steel), which makes a certain concentration of solid solution in the steel C atoms, which have excellent deep drawing performance and high bake hardening properties, but the strength of this type of steel is generally low. In order to improve the strength of this type of product, more alloys need to be added, most of which are high prices such as metal manganese. Metal, which will inevitably lead to a substantial increase in production costs, and will deteriorate the surface quality of steel sheets, especially the surface quality of galvanized products

Therefore, the strength of the above three steel types is difficult to reach a high level, and the tensile strength is basically below 400MPa.

Images