Microstructural evolution in creep tested electron beam welded Reduced Activation Ferritic Martensitic (RAFM) steel and 316LN stainless steel dissimilar weld joints has been studied at 823 K under different stress levels. The rupture life of the weld joints spanned between 17,596 and 190 h with variation in applied stress from 160 to 220 MPa. Failure of the weld joints occurred in the RAFM steel side at all stress levels. Microstructural examination showed that the failure location shifted from the unaffected base metal region of the RAFM steel to the ‘soft region’ within the heat affected zone (HAZ) in the RAFM steel side with decrease in applied stress. The strength mismatch between various regions within the HAZ of RAFM steel and the microstructural instability of ‘soft region’ in the RAFM steel are the two important factors which dictate the failure location and rupture life of the joints.

研究了蠕变测试电子束焊接的还原活化铁素体马氏体（RAFM）钢和316LN不锈钢异种焊接接头在不同应力水平下的微观组织演变。焊接接头的断裂寿命在17,596至190 h之间，施加的应力在160至220 MPa之间变化。在所有应力水平下，RAFM钢侧的焊接接头均发生故障。显微组织检查表明，随着施加应力的减小，失效位置从RAFM钢的未受影响的贱金属区域转移到RAFM钢一侧的热影响区（HAZ）内的“软区域”。