38Si2Mn2Mo钢下贝氏体和回火马氏体中的碳化物析出行为

PRECIPITATION BEHAVIOR OF CARBIDE IN LOWER BAINITE AND TEMPERED MARTENSITE IN 38Si2Mn2Mo STEEL

研究了 38Si2 Mn2 Mo钢等温下贝氏体中和淬火回火后马氏体中析出的碳化物。在下贝氏体中存在两组 ε碳化物 ,它们与贝氏体铁素体保持 Jack位向关系 ,而与奥氏体无固定取向关系 ,ε 碳化物的惯习面为 { 10 0 } b,未见碳化物在奥氏体一侧析出。表明下贝氏体具有碳过饱和度 ,ε 碳化物是从贝氏体铁素体中析出的 ,具有与回火马氏体相似的切变特征。

The carbides precipitated in the isothermal lower bainite and the tempered martensite in 38Si2Mn2Mo steel were studied using TEM. The results show that two groups of εcarbides exist in the lower bainite,they keep a Jack O.R. with the bainitic ferrite,but they don't keep fixed and unique O.R.with austenite matrix.The H.P. of εcarbide was determined to be ｛100｝ b/｛112—0｝ ε .The precipitation of carbide didn't be found in austenite .These show that a carbonsupersaturation occurred in the lower bainite,the εcarbide was precipitated from the bainitic ferrite,and the phase-transformation of bainite has the features of shear in analogy to the tempered martensite.