Is heat treatment required for welding chromium-molybdenum steel to austenitic stainless steel?
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In catalytic cracking units, many components are made of chromium-molybdenum steel, and preheating before welding as well as post-weld heat treatment are required. Conducting heat treatment at the site where maintenance is carried out can sometimes be inconvenient; more often, the material used is changed, with welding between chromium-molybdenum steels being replaced by welding between chromium-molybdenum steel and austenitic stainless steel in order to avoid on-site heat treatment. Is this a viable approach? What is the basis?
Generally, after welding chromium-molybdenum steel with heat-resistant steel electrodes, post-weld heat treatment is required. However, when austenitic stainless steel electrodes are used, post-weld heat treatment is usually not necessary. As for whether dehydrogenation treatment is needed, such treatment only requires a temperature of around 200 degrees and has no significant effect on the metal structure.
SH/T3520-2004 \"Welding Procedures for Chromium-Molybdenum Heat-Resistant Steels in the Petrochemical Industry\" contains explanatory clauses 4.2.2 and 4.2.3
I studied it carefully; thank you to the two people above
Stainless steel welding materials can be used for welding, without the need for heat treatment
Heat treatment after welding is required when welding chromium-molybdenum heat-resistant steels, but it is not necessary when welding stainless steels; however, hydrogen removal treatment is required in that case
Nickel-based electrodes are preferred; refer to SH/T3520 \"Welding Procedures for Chromium-Molybdenum Heat-Resistant Steels in the Petrochemical Industry\". Nickel in the weld can effectively prevent carbon migration or reduce the width of the carbon migration transition layer, thereby avoiding or minimizing the formation of martensite on the chromium-molybdenum steel side (martensite is brittle and prone to cracking)
Without manufacturing experience, my explanation might be incorrect; I hope someone with expertise in manufacturing can provide an answer based on their practical experience
When welding these two types of steel together, austenitic electrodes can be used, and heat treatment may not be necessary. However, when welding heat-resistant steel to stainless steel, attention must be paid to the effect of the different linear expansion coefficients at the operating temperature in order to avoid cracks.
I learned it; I really didn’t know before! ! Thank you! !
I’ve learned something new; I haven’t encountered this issue before