When strength welding is combined with expansion fitting, how should the heat treatment timing for the heat exchange tubes be determined?
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As the title suggests: When strength welding is combined with expansion fitting, how should the heat treatment timing for the heat exchange tubes be determined? The problems I encountered myself were eventually clarified; everyone is welcome to discuss them!
Correct manufacturing process: Strength welding --- Heat treatment --- Slight expanding
I have previously worked on equipment that required heat treatment, involving welded joints between heat exchange tubes and tube sheets. Due to issues with the heat treatment process, we resorted to methods such as surfacing the tube sheet with stainless steel in order to avoid heat treatment. When heat treatment was indeed necessary, for fixed-tube-sheet heat exchangers, a partial heat treatment approach was used: welding one end first followed by local heat treatment via expansion, then spot-welding the other end, and subsequently welding that end as well before applying local heat treatment through expansion. The device has been in use for 5 years, and it performs well.