Corrosion Behavior of an Additively Manufactured Functionally Graded Material

Abstract

Dissimilar metal welds (DMW) combine the high strength and cost benefits of ferritic stainless steels with the high corrosion resistance of austenitic steels, and are thus commonly used in different types of power plants. However, due to the abrupt change in properties, these joints are susceptible to premature failure. Work pieces with a smooth transition in composition and/or properties are referred to as "functionally graded materials" (FGM). When used as transition joints, FGM can enhance the lifetime of certain components. In the present study, the FGM were manufactured by using wire arc additive manufacturing employing cold-wire gas metal arc welding. Since the corrosion resistance of such FGM are still unknown, the corrosion properties of the FGM work piece were compared to those of a DMW work piece by means of electrochemical analysis using potentiodynamic polarization and a salt spray test. The FGM showed a 24 % lower average corrosion rate compared to the reference piece and no signs of pitting or galvanic corrosion. This shows the potential of FGM and further research should be carried out.