Production method of hot-galvanized low-alloy high strength steel having no yield point elongation and used for automobile sheets

Abstract

The invention relates to a production method of hot-galvanized low-alloy high strength steel having no yield point elongation and used for automobile sheets. The production method comprises smelting,continuous casting, hot rolling, acid continuous rolling and hot galvanizing procedures. The steel comprises chemical components in percentage by mass as follows: 0.060%-0.090% of C, smaller than or equal to 0.05% of Si, 0.65%-0.75% of Mn, 0.015%-0.025% of P, smaller than or equal to 0.010% of S, 0.025%-0.06% of Als, 0.025%-0.035% of Nb, smaller than or equal to 0.0040% of N and the balance Fe andinevitable impurities. By reasonable component design and control on key process parameters such as hot rolling coiling temperature and finishing elongation, dislocation gets rid of the effect of solute atom (Cottrell) anchoring, the yield point elongation can be completely eliminated, slip line defects in the re-machining forming process are avoided, the final surface quality of the product is improved, and the steel has excellent mechanical properties.

Description

technical field [0001] The invention belongs to the technical field of metallurgy, and in particular relates to a production method of hot-dip galvanized low-alloy high-strength steel HX340LAD+Z with no yield platform for automobile plates. Background technique [0002] With the rapid development of automobile lightweight and the improvement of environmental protection requirements, hot-dip galvanized low-alloy high-strength steel can reduce the thickness of the steel strip to achieve lightweight due to its high strength, and improve the corrosion resistance of the zinc layer after galvanizing Therefore, the application of hot-dip galvanized low-alloy high-strength steel is more and more extensive. [0003] At present, when most of the hot-dip galvanized low-alloy high-strength steels are subjected to tensile tests after annealing and galvanizing, there are different degrees of yield platforms on the stress-strain curves. When such yield platforms are reprocessed, slippage o...

AI Technical Summary

Problems solved by technology

CN104988389A discloses alloyed hot-dip galvanized steel with a tensile strength of 340MPa, and the yield strength is only 250-280MPa, and the strength level is not high

CN105239002A invented ultra-low carbon series continuous annealing cold-rolled automotive structural steel with tensile strength of 340MPa, low yield strength, high alloy content and high production cost

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