The temperature of dehydrogenation heat treatment and its purpose
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Dehydrogenation heat treatment, also known as post-heat treatment. That is, after welding, the welded part is heated to 250–350°C and held at that temperature for 2–6 hours; the purpose of this is to accelerate the escape of diffused hydrogen from the weld, thereby reducing the hydrogen content in the weld and the heat-affected zone and preventing the formation of cold cracks. Materials with a higher tendency to harden generally require hydrogen-removing heat treatment after welding to prevent the occurrence of cold cracks. In engineering practice, low-alloy steels with high strength levels, such as chromium-molybdenum steel and steels used for large-thickness high-strength spherical tanks, are usually considered for hydrogen extraction treatment.
If heat treatment is carried out immediately after welding. Hydrogen removal is not necessary; however, if welding is interrupted, hydrogen removal should be carried out promptly. It is best to perform hydrogen removal right after welding is completed