Tensile strength 600mpa level low cost high expansion hole steel plate and its production method

Abstract

The invention discloses a tensile strength 600MPa grade low-cost high-hole-enlargement steel plate and a production method thereof. The high-hole-enlargement steel plate is prepared from the following chemical components in percentage by mass: 0.15 to 0.20% of C, less than or equal to 0.30% of Si, 0.80 to 1.00% of Mn, less than or equal to 0.020% of P, less than or equal to 0.010% of S, 0.020 to 0.050% of Als, 0.010 to 0.030% of Ti, less than or equal to 0.0060% of N, and the balance of Fe and inevitable impurities. The production method of the steel plate comprises the processes of steelmaking, heating, rolling and cooling. The intermediate low C and conventional Mn are adopted, few amount of Si and Ti elements are added, and a cooling path is controlled, so that a hot rolled steel strip of which the tensile strength is 600 to 650MPa, the lower yield strength is 500 to 550 MPa, the elongation percentage A50 is more than or equal to 25%, and the hole enlargement rate is more than or equal to 95% is obtained, and the steel strip is low in cost, is excellent in performance and has strong market competiveness.

Description

technical field [0001] The invention belongs to the technical field of metallurgy, and in particular relates to a steel plate with a tensile strength of 600MPa grade and low cost and high hole expansion and a production method thereof. Background technique [0002] Hot-rolled steel sheets are widely used in automobile chassis, wheels, suspensions, and body structural parts. Due to the relatively complicated hole expansion and flanging deformation in the manufacturing process of wheels, suspensions and other components, the materials are required to have high hole expansion performance. Combined with the current situation of energy conservation and emission reduction, and the gradual advancement of automobile lightweight, the 330-500MPa grade steel used in the above parts is gradually replaced by the 600MPa grade steel grade, so the 600MPa grade high reaming steel has a broad market prospect. [0003] At present, the 600MPa level high-hole reaming steel produced at home and a...

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Problems solved by technology

[0003] At present, the 600MPa level high-hole reaming steel produced at home and abroad mostly uses low C, adding alloy elements such as Nb, Ti, Cr, Mo, etc., and uses the comprehensive effect of solid solution strengthening and precipitation strengthening of alloy elements to improve the material strength and ensure the plasticity of the material. However, due to the addition of precious metal elements such as Nb and Mo, the production cost of the existing 600MPa grade high reaming steel is relatively high

[0004] After searching the literature of the prior art, it was found that the Chinese invention patent CN 101928881 announced a hot-rolled high-hole expansion steel plate with a tensile strength of 590MPa and its manufacturing process. This invention uses low C components and adds 0.8-1.6% of Si, 0.8-1.6% Mn, a very small amount of Nb and Ti elements can achieve tensile properties above 590MPa and high hole expansion properties, but due to the addition of Si elements, the surface quality of the steel plate will decrease and the production cost will increase.

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