材料期刊网

本文用透射电子显微镜研究了具有代表性的六种低碳马氏体钢的显微组织,结果表明:含碳量较低的马氏体钢(指0.1—0.25wt-%C),淬火后一般都存在薄膜状残余奥氏体,低碳马氏体钢淬火时不可避免有自回火现象,自回火沉淀出的碳化物是六方晶格的ε碳化物,六种钢都能找到具有局部孪晶亚结构的板条晶,低碳马氏体在350—400℃回火时,ε转化成Fe_3C;回火温度提高至500℃时,孪晶消失,但马氏体板条晶的轮廓在600℃时仍可维持原状.

Six representative low carbon martensitic steels were analyzed under TEM,Observations showed as follow:The thin retained austenite films usually exist in the structure of the low car-bon(namely,0.1—0.25 wt-%C)martensitic steels;ε-carbides formed in auto-tempering precipitate on the matrix of the lath mar-tensites;Internal twins exist in part of some lath matrix of the six steels;ε-carbides transform into cementites when tempered at 300-400℃.Cementitesform in three sites,lath boundaries,{110}_M planes and twin boundaries;Twins disappear when tempering temperature raise to 500℃ but the outlineof lath boundaries still keeps its original shape.