热处理对核级不锈钢焊缝组织和点蚀性能的影响

Effect of heat treatment on microstructure and pitting corrosion behavior of nuclear grade stainless steel weld

采用激光焊接技术对国产核级不锈钢进行焊接,通过显微组织分析和点腐蚀试验,研究不同热处理温度和时间对焊缝组织和点蚀性能的影响规律和机制。结果表明:原始焊缝中残留着大量板条状δ-铁素体相,在敏化区间内,提高热处理温度,焊缝中δ-铁素体相细化,含量降低,导致焊接接头抗点蚀性能降低;同一温度下延长热处理时间,δ-铁素体相含量下降且没有析出相析出,焊接接头抗点蚀性能增强。

Laser beam welding technique was employed to weld nuclear grade stainless steel.By microstructure observation and corrosion test,the effect of heat treatment on microstructure and pitting corrosion behavior of the weld ioint was investigated.The results indicate that there is a large amount of residual lath δ-ferrite phase in the weld joints before heat treatment.With increasing of the heat treatment temperature in the sensitization temperature range,the δ-ferrite phase is refined,and its amount decreases,which results in the decrease of pitting corrosion resistance of the weld.Increasing heat treatment time at the same temperature decreases amount of the δ-ferrite phase,and no precipitate phase is precipitated,leading the improvement of pitting corrosion resistance of the weld joints.