Study on the Deformation Resistance and Microstructure of Interstitial Free Steel under Different Rolling Processes
摘要
The effect of two different rolling processes on the deformation resistance and microstructure of IF steel was explored by using a Gleeble-3500 thermal simulation testing machine, morphological analysis and theoretical calculation. The results show that the deformation resistance effected by deformation temperature in both the high-temperature direct rolling (HTDR) process and the conventional hot charging (CHC) process exhibited a non-monotonous change trend. The deformation resistance increased with the decrease in deformation temperature in the single-phase region, but decreased in the ferrite + austenite dual-phase region. Additionally, when the deformation temperature was higher than 800 °C, the deformation resistance of the CHC process was greater than that of the HTDR process, while the deformation resistance of the HTDR process was larger than that of the CHC process when the deformation temperature was lower than 800 °C. This phenomenon is closely related to fine grain strengthening and Ti-containing precipitation. At the deformation temperature above 800 °C, the fine grain strengthening played a main role in deformation resistance as the original austenite grain size in the CHC process was smaller than that in the HTDR process, whereas, at the deformation temperature below 800 °C, the more precipitation particles in the HTDR process resulted in the larger deformation resistance than that in CHC process. In addition, based on the deformation resistance data, a multiplicative correction was made to the deformation resistance mathematical models of Guan Kezhi and Zhou Jihua. The determination coefficient R2 is increased from the original 0.9443 to 0.9895 for CHC process, and from 0.8992 to 0.9802 for HTDR process, respectively, indicating a better prediction accuracy.