微合金化热轧TRIP钢的工艺模拟

 借助MMS-300热模拟试验机研究了控轧温度区间、终冷温度、贝氏体区等温处理以及冷却路径对微合金化热轧TRIP钢组织演变规律的影响。结果表明，随着控轧温度区间“下调”，组织中的铁素体晶粒越来越细小，铁素体量逐渐增加，残余奥氏体量则先增加后减少。终冷温度升高时，组织中的残余奥氏体量也呈现出先增加后减少的变化趋势，而贝氏体温度范围等温时间的延长使残余奥氏体量增加。相对于“缓冷+快冷”，轧后采用“快冷+缓冷+超快冷”冷却路径更有助于铁素体晶粒的细化和奥氏体的残留。在“快冷+缓冷+超快冷”冷却路径下，当控轧温度区间为900~840℃，缓冷温度范围为710~680℃，贝氏体等温处理制度为450℃×5min时，组织中的残余奥氏体量达到最高值113%。

Simulated Thermomechanical Process of Hot-Rolled Microalloyed TRIP Steel

Effects of controlled rolling temperature interval,finish cooling temperature,isothermal holding in bainite transformation region and cooling route on the microstructural evolution of hot-rolled microalloyed TRIP steel were investigated by means of MMS-300 thermomechanical simulator.The results show that ferrite grains get finer,ferrite content increases gradually and the amount of retained austenite first increases then decreases with the down-regulation of controlled rolling temperature interval.The amount of retained austenite in the microstructure also exhibits the same trend as finish cooling temperature increases.However,it increases with prolonging the holding time in the bainite temperature range."Rapid cooling plus slow cooling plus ultra-fast cooling" cooling route after rolling contributes to refine the ferrite grains and retain austenite in comparision with "slow cooling plus rapid cooling" cooling route.The amount of retained austenite reaches the maximum value of 11.3% when controlled rolling temperature interval 900-840 ℃,slow cooling temperature range 710-680 ℃ and isothermal treatment process in bainite transformation region 450 ℃×5 min are adopted under the three-step cooling route.