关键词: 异质接头 , 碳迁移 , 时效处理 ,  , 增碳区 , 脱碳区 , 贝氏体退化 , 显微组织,  , 铁素体

Abstract: The welding of austenitic stainless steel with low alloy heatresistant steel was usually used in the connection of convection tubes which can be found in power station boiler. These two materials were significantly different in the composition and organization. The carbon may diffuse if the two dissimilar joints were in the high temperature conditions, forming a recarburization zone and a decarburization zone. After the aging treatment for the dissimilar joint at 500 ℃/100 h and observing the changes of the composition and the microstructure on both sides of the fusion zone, The result show that， after the aging time, the carbon content increased in the fusion zone and a large number of carbide precipitated, granular bainite and upper bainite in the base material under welding degraded and transformed into ferrite and sorbite.

Key words: Dissimilar joint,    ,  Carbon diffusion,    ,  Aging,    ,  Recarburization,    ,  Decarburization,    ,  Bainite degeneracy,    ,  Microstructure,   ,  Ferrite