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研究了无镍高氮奥氏体不锈钢的脆韧转变（BDT）。在176 K、273 K和336 K进行的落锤试验结果表明，尽管Fe-25 Cr-1．1 N（质量分数，％）是面心立方结构的奥氏体合金钢，但仍展现出显著的脆韧转变现象。对冲击试验试样的塑性变形观察表明，BDT是由于低温下差的延展性所致，这与铁素体钢的情况是一致的。为了测量BDT的激活能，利用4点弯曲试验研究了应变速率与BDT温度的关系。研究发现，BDT温度与应变速率之间的依赖关系不显著，且BDT温度对应变率的Arrhenius曲线表明Fe-25 Cr-1．1 N钢BDT的激活能比低碳铁素体钢的高得多。从滑移位错与溶质氮原子发生交互作用导致低温下位错可动性降低这一角度，本文探讨了高氮钢特有的BDT及其高激活能的本质原因。“,”The brittle to ductile transition (BDT ) in nickel free high nitrogen austenitic stainless steel was investigated.Falling weight impact tests at 176,273 and 336 K revealed that Fe-25Cr-1.1N (wt-%)austenitic steel exhibits a sharp BDT in spite of being a face centred cubic alloy.The plastic deformation observed following the impact tests indicated that the BDT is induced by poor ductility at low temperatures,as is the case with ferritic steels.To measure the activation energy for the BDT,the strain rate dependence of the BDT temperature was examined using four-point bending tests.The BDT temperature was found to be weakly dependent on strain rate. Arrhenius plots of the BDT temperature against strain rate showed that the activation energy for the BDT of Fe-25 Cr-1 .1 N steel is much higher than that of low carbon ferritic steels.The origins of this distinctive BDT and the large value for its activation energy in this high nitrogen steel are discussed in terms of the reduction in dislocation mobility at low temperatures because of the interactions between the glide dislocations and the solute nitrogen atoms.