前言众所周知,工具钢正常淬火态马氏体的碳含量约为0.5—0.6％,相应的马氏体形态为板条(位错)和片状(孪晶)混合组织。马氏体形核也是非均质的,早在六十年代就有马氏体沿母相晶界、孪晶界和相界优先形核的报导。然而迄今为止,对晶界上优先形成的马氏体类型、亚结构及其对机械性能的影 Preface It is well known that the carbon content of the normal quenched martensite of tool steels is about 0.5-0.6%. The corresponding martensite morphology is lath (dislocations) and lamellar (twin) mixed structures. Martensite nucleation is also heterogeneous, as early as the sixties there martensite along the parent grain boundaries, twin boundaries and phase boundary preferential nucleation reports. However, so far, the preferential formation of martensite on the grain boundary type, substructure and its impact on mechanical properties