During a recent project, a client requested the development of an ASME Section IX WPS for the joining of SA 693 Type 630 (17-4 precipitation hardened stainless steel) to SA 516 Gr. 70 carbon steel. Their existing WPS (welding procedure specification) joined AISI 4140 to SA 516 Gr. 70 and there had been several instances of cracking occurring.
The 17-4 PH stainless steel was chosen primarily for its high hardness capability while also being relatively resistant to cracking; the application would be in a rolling situation subject to wear. It may be debated whether ASME Section IX was the most appropriate code to use, however, the testing that would have been conducted would not have changed by using a different code.
Have you read this highly requested article from the April issue of Stainless Steel World Americas? Take five minutes to read it now: https://www.ssw-americas.com/webarticles/2021/04/12/developing-a-welding-procedure-for-joining-17-4-ph-to-sa-516.html