Effect of Coiling Temperature and Cold Reduction Ratio on Microstructure and Mechanical Property of Nb Microalloying Added Phosphorus High Strength IF Steel

Abstract

Nb microalloying added phosphorus high strength IF steel was used to study the effect of coiling temperature and cold reduction ratio on the microstructures and mechanical properties. The experimental results showed that the recrystallization had finished. Under coiling temperature 650°C and cold reduction ratio 75%, and under coiling temperature 600°C or 700°C and cold reduction ratio 65%, the yield strength, tensile strength were lower , the elongation was higher. The plastic strain ratio r value and the strain hardening exponent n value were reached the higher value, respectively, the r value was approximate 1.8, and the n value was approximate 0.26. Therefore, the suggested the optimal coiling temperature is 700°C, cold reduction ratio is 65% to 75%, and it is optimal process of Nb microalloying added phosphorus high strength.