After heat treatment, the 304 material fittings are welded – does the equipment still require heat treatment?
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After heat treatment of the equipment, and due to structural improvements resulting from the manufacturing process as well as the welding of 304 material fittings, is the equipment still required to undergo heat treatment?
450–850°C is the sensitization temperature for stainless steel; within this temperature range, chromium-rich carbides precipitate along the grain boundaries of the stainless steel, leading to chromium depletion at those boundaries and thereby causing intergranular corrosion in the sensitized state. Therefore, after welding 304 stainless steel, heat treatment is not very effective. If post-weld treatment is necessary, the maximum temperature must not exceed 400°C, and the holding time should be extended. Or undergo solution treatment at 1050 degrees.
For welding 304 nozzles to carbon steel and low-alloy steel equipment, it is best to avoid post-weld heat treatment; in such dissimilar metal welds, heat treatment can easily cause cracks in the weld seam and also lead to sensitization of the 304 material.
For welding 304 nozzles to carbon steel and low-alloy steel equipment, it is best to avoid post-weld heat treatment; in such dissimilar metal welds, heat treatment can easily cause cracks in the weld seam and also lead to sensitization of the 304 material.
What material was the original equipment made of, and what heat treatment was it subjected to? This is related to whether further heat treatment is carried out!