Comparison on the microstructure and corrosion behavior of Inconel 625 cladding deposited by tungsten inert gas and cold metal transfer process

Abstract

Microstructure and corrosion behavior of cold metal transfer (CMT) and tungsten inert gas (TIG) cladding were compared by characterization, electrochemical measurements and exposure tests. Microstructure characterization indicates the difference in kernel average misorientation and microhardness between CMT and TIG claddings is negligible. However, the CMT cladding shows a strong texture at 〈001〉║rolling direction (RD) while the strongest texture of TIG cladding is along <001>║normal direction (ND) orientation. In addition, the percentage of Laves phase in the CMT cladding is generally lower than the TIG cladding. Electrochemical measurements and exposure tests indicate the corrosion resistance gradually increases with increasing of the distance to the fusion boundary of both claddings. The CMT cladding generally has better corrosion resistance than the TIG cladding. However, higher pitting tendency of the CMT cladding was observed adjacent to the fusion boundary likely due to the existence of large MC carbides.