Hot rolled high plastic stain ratio structural steel sheets was used to study the effect of cold reduction ratio and annealing process on the microstructures and mechanical properties. The results showed that the structural steel sheets was recrystallize finished after cold rolling follow different cold reduction ratio and batch annealing(annealing temperature 670 degrees C and soaking time 5h) under experimental condition. When the cold reduction ratio was increased, the yield strength and tension strength increase, the elongation reduced followed different heating speed. The plastic strain ratio r value reached the maximum with cold reduction ratio of 50%, when the cold reduction ratio was increased, the r value was gradually reduced, However, the strain hardening exponent n value was gradually reduced. In the end, that suggested the optimal cold reduction ratio is 40% to 50%, and heating speed is 20 degrees C/h, consequently that obtained good match of mechanical properties and punching property.
