Development of 40 to 50 kg/mm~2 tensile strength, highly formable cold-rolled low carbon steel by α+γ phase annealing

摘要

The effects of key alloy and process parameters on the mechanical properties of high strength, highly formable low carbon sheet steels have been determined by a combination of laboratory processing, Taguchi Design of Experiments method, and multiple linear regression analysis. Factors studied include C, Mn, P, hot mill coiling temperature, inline annealing temperature, and annealing line speed. Tensile strength levels were varied from 40 to 50 kg/mm~2 with elongation of 30 to 40%. Annealing conditions were varied from partial to full recrystallization in both the single and α+γ two phase region. Effects of the chemistry and process parameters on the mechanical properties will be discussed, with particular emphasis on conditions required to produce a hot dipped galvannealed product meeting 45 kg/mm~2 tensile strength and 35% elongation minimum requirements.