Hot wire TIG multi-layer and multi pass welding tests were conducted on 10Cr9Mo1VNb boiler steel,and the welded joints were subjected to post weld heat treatment at different temperatures(740-790 ℃)and time(1-4 h).The effects of post weld heat treatment on the microstructure and properties of the joints were analyzed using hardness,metallography,room temperature tensile testing,Charpy impact testing,SEM and other experimental methods.The results show that the post weld heat treatment can transform the martensite formed in the welding process into tempered martensite,which can significantly improve the uniformity of the microstructure and properties of each zone of the joint.When subjected to heat treatment at 740 ℃,the strength slightly reduces with the increase of heat treatment time,while both the plasticity and toughness further improve.However,when subjected to heat treatment at 790 ℃,the strength,plasticity and ductility decrease with the increase of time,mainly due to the coarsening of carbides such as M23C6 in the joint.
post weld heat treatmenthot wire TIG welding10Cr9Mo1VNb boiler steelmicrostructuremechanical properties
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