一、前 言 为了维持高的硬度和强度并兼有足够的韧性,高碳工具钢和合金工具钢通常进行低温范围的等温淬火,使在钢的基体组织中形成一定数量的下贝氏体组织。用金相显微镜很难区别下贝氏体组织和经低温回火后的马氏体组织,尤其是在这两种组织都十分细小的情况下。用透射电子显微镜观察上述两种组织时,能清楚地分清它们各自的特征。为 I. INTRODUCTION In order to maintain high hardness and strength with sufficient toughness, high-carbon tool steels and alloy tool steels are usually isothermal quenched in the low temperature range to form a certain amount of lower bainite in the matrix structure of the steel. It is difficult to distinguish between lower bainite and low temperature tempered martensite using a metallographic microscope, especially when both are very fine. When the above two tissues were observed with a transmission electron microscope, their respective characteristics were clearly distinguished. for