在-60 ℃至室温范围内，采用夏比冲击试验测定材料的韧脆转变温度（DBTT），并通过对冲击断口的扫描电镜（SEM）观察和透射电镜（TEM）观察等方法，对几种不同氮含量奥氏体不锈钢在低温下发生韧脆转变的现象进行了研究。结果表明：在Charpy冲击试验中,除大量高密度位错和层错外未发现奥氏体基体结构的变化，随温度的降低，其断口形貌由韧窝→韧窝和似准解理→似解理脆断变化，断裂形式为以穿晶为主的混合断裂。

The DBTT of superhigh nitrogen containing austenitic stainless steel was measured by Charpy impact test from roomtemperature to -60 ℃ , and the ductility and brittleness transition at low temperature was investigated by SEM, TEM and XRD methods. The results show that except a lot of fault ribbons and high density dislocations the structure of austenitic matrix is not changed during Charpytype test.The fracture is changed from dimple to dimple and cleavagelike to cleavagelike, and fracture mode is a mixed one with transgranular as primary.