Does welded meat need heat treatment?
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Welded meat does not require heat treatment. “"Weld meat" usually refers to the weld metal formed during the welding process, while "heat treatment" is a process for metallic materials. In industrial welding, whether the weld seam (i.e., the "weld meat") requires heat treatment depends on the material type, structural purpose, and work environment. The following are common situations: Cases requiring heat treatment: When welding thick-walled pressure vessels, pipelines or large steel structures, in order to eliminate residual stress and prevent delayed cracks, post-weld heat treatment (PWHT), such as stress relief annealing, is often required. When using materials with a large hardening tendency such as high-strength steel and low-alloy steel, tempering or normalizing treatment is required after welding to improve the structural properties. Equipment serving in high temperature, high pressure, and corrosive environments (such as petrochemical and nuclear power) must be heat treated to improve stress corrosion resistance. When heat treatment is not required: Austenitic stainless steel welded joints generally do not undergo post-weld stress relief heat treatment. For ordinary low carbon steel sheet welding, small structural parts or non-load-bearing parts, heat treatment can be omitted if there are no special requirements. Aluminum alloy containers generally do not require heat treatment after welding. Therefore, whether to heat treat "welded meat" needs to be comprehensively judged based on materials, design specifications and usage conditions.
Welding heat treatment does require a case-by-case analysis. Add some practical experiences for reference: For thin-walled stainless steel pipes (such as those below DN50), our projects usually do not perform post-weld heat treatment, but we will strictly control the argon gas protection effect to avoid oxidation that affects corrosion resistance. I encountered a case where the omission of PWHT in a chemical project resulted in hydrogen-induced cracking of the weld. It was later found that the welding material was not baked properly and the ambient humidity exceeded the standard. It is recommended that important structures still undergo hydrogen elimination treatment according to specifications. Nowadays, some new processes, such as vibration aging treatment, can replace traditional heat treatment and are especially suitable for large-scale structures on site, but process evaluation must be done first. For details, you can check the exemption clauses in the NB/T 47015 standard, which have detailed regulations based on material thickness and joint type. What material are your welding parts made of?