Effects of Continuous Annealing Process Parameters on the Microstructure and Mechanical Properties of Dual Phase Steel

Due to the difference in chemistries and manufacturing processes applied, the microstructure and mechanical properties of DP780 steel produced by different production lines may be inconsistent. Annealing experiments are designed and carried out in the laboratory based on the actual industrial production process in order to investigate the effects of continuous annealing process parameters on the microstructure and mechanical properties of DP steel quantitatively. The results show that the effect of intercritical temperature is continuous while the sensitive interval and non‐sensitive interval should be considered in terms of the effect of slow cooling temperature, over‐aging temperature, and strip speed. The influence degree is defined to quantitatively compare the effects of the influencing factors, which find that the over‐aging temperature has the most influential effect on the tensile strength while the effect of the slow cooling temperature ranks second and the intercritical temperature has a minimal impact. The influence degrees on elongation of all the three factors are similar. The results from this study are helpful to efficiently adjust the microstructure and mechanical properties of DP steel.