合金元素和工艺参数对热轧TRIP钢动态相变的影响

利用Gleeble热模拟试验机进行单轴压缩试验,研究了C-Mn-Si TRIP钢和C-Mn-Al-Si TRIP钢过冷奥氏体形变过程的组织演变,分析了合金元素和工艺参数对过冷奥氏体动态相变的影响.与等温相变相比,C-Mn-Si钢和C-MnAl-Si钢动态相变动力学明显加快.与C-Mn-Si钢相比,用质量分数约1%的Al替代Si后,C-Mn-Al-Si钢的A₃温度明显提高,在相同变形工艺条件下C-Mn-Al-Si钢过冷奥氏体动态相变较易发生,而C-Mn-Si钢动态相变得到的铁素体晶粒比较细小.减小动态相变前奥氏体晶粒尺寸,有利于过冷奥氏体动态相变的进行.提高过冷奥氏体形变时的变形温度或应变速率均对动态相变产生一定的阻碍作用,但影响不显著. 

Influences of alloying elements and processing parameters on the dynamic transformation of undercooled austenite in hot-rolled TRIP steels

The microstructural evolution of undercooled austenite in C-Mn-Si TRIP steel and C-Mn-Al-Si TRIP steel during hot deformation was investigated by hot uniaxial compression testing on a Gleeble-1500 hot simulator, and the influences of alloying elements and processing parameters on the dynamic transformation of undereooled austenite were analyzed. It is found that the dynamic transformation kinetics of undercooled austenite in C-Mn-Si TRIP steel and C-Mn-Al-Si TRIP steel is faster obviously than the isothermal transformation kinetics of undercooled austenite. In comparison with C-Mn-Si TRIP steel, the A₃ temperature of C-Mn-AI-Si TRIP steel is elevated markedly by the substitution of 1% Al for Si, and the dynamic transformation of undercooled austenite in C-Mn-AI-Si TRIP steel is faster at the same processing conditions. But the averave size of ferrite grains fomred by the dynamic transformation in C-Mn-Si TRIP steel is finer. The refinement of austenite grains before the dynamic transformation is of benefit to the development of the dynamic transformation of undercooled austenite. Increasing the deformation temerature or the strain rate of undercooled austenite during hot deformation has a retarding effect on the dynamic transformation of undercooled austenite, but this effect is not marked.