【摘要】 用高温金相显微镜动态观察4种原始组织的T10A钢试样在真空加热及冷却时的石墨析出现象。观察发现在奥氏体晶粒晶界、亚晶界、孪晶界、残留渗碳体(碳化物)或夹杂物处优先析出石墨晶核,沿其六方点阵基面择优方向长大。剥层分析表明石墨呈薄层结构平铺在试样观察表面上,而其内部无石墨析出。T8A,T10A及T12A钢的二次石墨析出温度分别为800℃,850℃,900℃,3种钢的共析温度均为720～740℃。更多还原

【Abstract】 By means of high temperature microscope,graphite precipitation from T10A steel specimens with 4 kinds of original structures has been dynamicly observed when heated and cooled in vacuum.The results show that the precipitation give priority to form the graphite nucleus at the austenific grain boundary,sub-boundary,twin boundary,undisolved cementite or inclusions and it’s selevtive growth can be easy along with the fundamental faces of hexagonal lattice.It is confirmed by the layer peeled off analysis that thin layer of graphite lays on the specimen surface observed at level condition,but inside graphite precipitation of specimens doesn’t occur.The graphite precipitational temperatures of three high carbon steels(T8A,T10A,T12A)are 800 ℃,850 ℃ and 900 ℃ approximately and eutectoid temperatures are 720 ℃~740 ℃.更多还原