热轧工艺中加热温度对IF钢组织性能的影响

选取Ti-Nb-IF钢热轧工艺中的加热温度为影响因素,采用显微观察、TEM二相粒子分析、织构分析等实验分析手段,研究了1 140℃和1 214℃两种热轧加热温度制备的Ti-Nb-IF钢样品在随后的冷轧、退火和平整过程中显微组织演变和织构演变特征的影响及最终产品的力学性能.结果表明,低温加热有利于IF钢屈强比的降低及深冲性能的提高,加热温度为1 140℃比1 214℃,其屈服强度可降低30 MPa,塑性应变比可提高0.16.其主要原因为低温加热工艺保障IF钢热轧后产生粗大的二相粒子和细小铁素体晶粒,在随后的冷轧和退火处理过程中产生分布均匀和强的γ再结晶织构.

Effect of Heating Temperature on Structure and Properties of IF Steel During Hot Rolling

The heating temperature was taken as an influencing factor on controlling the properties of Ti-Nb-IF steel during hot rolling. To study the relationship among the heating temperature, steel structure and properties, the microstructure, second-phase particles and texture of Ti-Nb-IF samples hot-rolled at 1140°C and 1214°C were analyzed separately. The results showed that the lower heating temperature (1140°C) is more beneficial to improving mechanical properties than rolled at 1214°C, i.e., the yield strength decreases by 30 MPa with plastic strain ratio increases by 0.16 at 1140°C. The main reasons are elucidated by experimental results as follows: When Ti-Nb-IF steel sheets are hot-rolled at 1140°C, bigger second-phase particles and finer ferrite grains are available to provide homogeneous appearance and strong γ recrystallization texture in such subsequent processes, as cold rolling and annealing.