Determination of Cold Reduction Ratio of Batch Annealing IF Steel

Two kinds of hot rolled IF steel added with Ti and Nb or added with Ti used to study the effect of cold reduction ratio on the microstructures, mechanical properties and textures of IF steel. The results showed that the IF steel was recrystallize finished after cold rolling follow different cold reduction ratio and batch annealing(annealing temperature 720 ℃ and soaking time 5 h) under experimental condition. When the cold reduction ratio was increased, the grain changed fine and uniformity; the texture of IF steel was stronger, as the textures had a trend with 111 texture. The plastic strain ratio r90 value reached the maximum with cold reduction ratio of 70%, when the cold reduction ratio was increased, the r90 value was gradually reduced; however, the strain hardening exponent n90 value was gradually reduced. Finally, it was suggested that the optimal cold reduction ratio was 70%~80%, consequently that can obtain good deep punching property.