采用低温急冷大压下细化铁素体组织

Ferrite Grain Refinement by Large Deformation at Low Temperature After Rapid Cooling

以SS40 0为研究对象 ,在Gleeble1 5 0 0热模拟机上 ,测定了在 85 0℃未变形及变形的奥氏体CCT曲线 ,研究了低温急冷大变形条件下变形温度、应变量、过冷度对铁素体变形行为以及对铁素体晶粒细化的影响·结果发现通过采用低温大变形可以得到平均晶粒直径约为 1 86μm的细小的铁素体组织 ,铁素体体积分数可达 85 %以上 ,在铁素体晶内和边界有碳化物析出·研究表明 ,低温、急冷、大变形可以有效地提高铁素体形核的驱动力 ,增加铁素体形核率 ,使晶粒大大地细化·

The CCT diagrams of 50% compressive deformation austenite and undeformed austenite at 850?℃ were investigated and the effect of the deformation temperature, reduction, and cooling rate on ferrite transformation behavior and the grain refinement by large deformation at low temperature after rapid cooling were studied on the Gleeble 1500 thermomechanical simulator for the low carbon steel SS400. It is shown that the very fine ferrite microstructure can be obtained and the ferrite diameter is about 1 86?μm, and the fraction of ferrite is up to 85%. Carbides were precipitated at the grain boundary of ferrite. The research indicates that low temperature, large deformation and rapid cooling can effectively improve the nucleation driving force, increase nucleation rate and greatly refine the ferrite grain.