Dissimilar Metal Welding Challenges Involving Chrome-Moly & Other Alloy Families

One of the major challenges facing the welding industry is joining dissimilar materials. This is especially true when joining chrome-moly and creep strength-enhanced ferritic (CSEF) steels to low carbon, austenitic stainless steels and even nickel base alloys. The traditional codes are nearly silent on the issue. Operating conditions, whether constant or varying, can also affect what must be considered to achieve satisfactory results. Many design, shop, or field organizations do not have or have lost expertise in this area. This paper addresses issues including design, code requirements, material properties, weld properties, preheat/post weld heat treatment, buttering and transition material approaches plus practical considerations. Case histories and practical examples are provided to illustrate proper implementation of dissimilar welding.