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本文利用 TEM 和 SEM 探讨了一种奥氏体热作工具钢的淬火敏感性和断裂行为,并指出试验材料的淬火敏感性与高温条件下获得的空位的“冻结”程度有关。随固溶加热后冷速的下降,空位在晶界和位错上湮灭的数量增加,空位“冻结”的百分比下降,从而减少了时效过程中 MC 强化质点的体积密度(N_v)。断裂塑性对固溶后的冷速有一“上凸”曲线关系,其形成原因在于晶内强度对晶内变形的均匀性以及晶界处应力集中的松弛导致的相反影响。
In this paper, the quenching sensitivity and fracture behavior of a austenitic hot work tool steel were investigated by TEM and SEM. The quenching sensitivity of the test material was also related to the degree of “freezing” of vacancies obtained at high temperature. With the decrease of cooling rate after solution heating, the number of vacancies annihilated in the grain boundaries and dislocations increased, and the percentage of vacancies “frozen” decreased, thus reducing the bulk density (N_v) of MC-strengthened particles during aging. Fracture plasticity has a “convexity” curve on the cooling rate after solid solution. The formation of the fracture plasticity is due to the intragranular strength on the uniformity of intragranular deformation and the opposite effect caused by the relaxation of stress concentration at grain boundaries.