高温运行对镍基焊缝异种钢接头显微组织的影响

采用光学金相、显微硬度等试验方法，对12Cr1MoV和0Cr17Ni12Mo2两种管材的镍基焊缝异种钢接头显微组织，进行焊后状态和高温运行后状态对比分析试验。结果表明，高温运行后，在12cr1MoV侧母材、热影响区，显微组织中出现了碳化物的球化倾向。焊后状态12Cr1MoV侧熔合区存在马氏体层和异相界面，高温运行后出现了明显的碳迁移现象：12Cr1MoV侧半岛熔合区存在的马氏体层，高温运行后也发生碳迁移。高温运行后12Cr1MoV侧熔合区以及半岛熔合区各处显微硬度明显下降。该结果与组织中碳化物的析出和碳迁移、应力松弛以及珠光体中碳化物的球化倾向等不利因素有关。

EFFECT OF HIGH TEMPERATURE RUN ON MICROSTRUCTURE OF DISSIMILAR STEEL JOINT WITH Ni-BASED WELD

By adopting optical metallography, micro-hardness examination etc., the comparative test to the microstructure of the dissimilar steel tube joint (12Cr1MoV and 0Cr17Ni12Mo2) with Ni-based weld between in as-welded condition and after the high temperature run was carried out. The results show that after the high temperature run, the carbides have the spheroidizing trend in the base metal and HAZ (heat affected zone) of the 12Cr1MoV side. The fusion zone of the 12Cr1MoV side possesses the martensitic layer and the interface of dissimilar phase, and the carbon migration takes place obviously in this zone after the high temperature run. The carbon migration also takes place in the martensitic layer of the peninsular fusion zone on the 12Cr1MoV side after the high temperature run. The micro-hardness of the fusion zone and the peninsular fusion zone of the 12Cr1MoV side decrease evidently after the high temperature run. These results are related to the carbides' precipitation, the carbon migration, the stress relief and the carbides' spheroidizing trend of the pearlite.