Welded parts heat treatment
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For carbon steel and low-alloy steel weldments, GB150 requires that the temperature upon exit from and entry into the heat treatment furnace after welding not exceed 400°C. Why is this?
When entering the furnace, there is a transition from room temperature to the furnace temperature; when exiting the furnace, there is a transition from the furnace temperature back to room temperature. The temperature difference in either case should not be too large, as rapid heating or cooling will generate high stresses
The temperature at which the part is taken out of and put into the furnace for post-weld heat treatment should not exceed 400°C. Why is 400°C chosen as this limit? Instead of 300°C or 500°C?
Because the value in ASME is 425°C
400 degrees – is this the experimental value? PS: ASME UCS-56 (d) states that when the temperature reaches 425 degrees, the container can be allowed to cool in the air
To be honest, it comes from ASME
Of course, this value is not an ASME invention either; there is likely decades of experience behind it