Niobium and titanium composite added ultra-low carbon baking hardening steel plate and manufacturing method thereof

Abstract

The invention relates to an ultra-low-carbon roasting hardened steel sheet with composite addition of niobium and titanium and a manufacturing method thereof, which belong to the material processing technical field. The compositions in weight percent of the ultra-low-carbon roasting hardened steel sheet are 0.002 to 0.005 percent of carbon, less than or equal to 0.5 percent of silicon, 0.9 to 1.2 percent of manganese, 0.08 to 0.1 phosphor, less than or equal to 0.06 percent of sulfur, 0.02 to 0.05 percent of aluminum, less than or equal to 0.06 percent of nitrogen, 0.01 to 0.02 percent of titanium, 0.01 to 0.02 percent of niobium, and the balance being iron. The microalloy titanium in the steel is used for fixing the carbon, the nitrogen, the sulfur and the niobium in the steel and controlling the carbon, and simultaneously has the function of thinning crystal grains. The the ultra-low-carbon roasting hardened steel sheet has the advantages that the ultra-low-carbon roasting hardened steel sheet can simultaneously have high strength, r value, extensibility and BH value and good room temperature resistant timeliness after the required steel undergoes hot rolling, cold rolling and continuous annealing.

Description

Technical field: [0001] The invention belongs to the field of metal material processing, and in particular relates to an ultra-low-carbon bake-hardening steel plate compounded with niobium and titanium and a production process thereof. Background technique [0002] The emergence of ultra-low carbon steel series as the third generation of deep-drawing steel should be attributed to the research on interstitial-free steel. Comstock et al. first pointed out in 1949 that a sufficient amount of Ti (Ti≥4(C+N)) was added to low carbon steel generally containing 0.05% C and 0.003% N, so that the C and N atoms in the steel were completely Precipitation into Ti (CN) will make the steel have excellent deep drawing performance. And retain a certain amount of solid-solution C atoms in the ferrite, so that the annealed steel plate can be hardened after cold working and baking paint treatment; at the same time, a corresponding amount of P is added to achieve solid solution strengthening an...

AI Technical Summary

Problems solved by technology

Since the bake-hardened steel sheet (nitrided steel sheet) produced at that time had a high aging resistance at room temperature and poor formability, it was not adopted by the automobile manufacturing industry.

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