Cd4MCu is a cast duplex stainless steel with not so good weldability. Advice would be to use matching filler wire /electrode. Recommendation is to solution anneal the weld after welding, if the weld thickness is large, typically over 1/2", or else weld with very good control over heat input and interpass temperature.
Generally this grade of Duplex S.S ( which is added with Copper) is preferred for corrosion resistance in acid media. What's the media in your case?? . If the service media is such that choice of Cd4MCu is a must then 308/308L filler metal would not match the corrosion requirements.
See the attached articles which explains the pros and cons on welding of this alloy. The second one Q&A is an extract from AWS-Welding Journal, and explains this alloy in details.
I hope this would be of help to you.
Welding & Metallurgical Specialist & Consultant
From: firstname.lastname@example.org [mailto:email@example.com] On Behalf Of firstname.lastname@example.org
Sent: Thursday, January 05, 2012 4:46 AM
To: Materials & Welding
Subject: [MW:13415] Filler welding for A351 Gr CD4 M Cu
I chose type E308 & E 308 L filler welding for A351 Gr CD4 M Cu material, the choice was made, as per ASME Section II Part C code,
Question: Is it a good choice?
Project engineer (SONATRACH Algeria)
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