Interpass Temperature Limit

The interpass temperature is the temperature the weld metal may have before laying the next pass. If you push it too high, you get coarse grain and the material loses toughness and strength. With some steels, the structure also gets harder and more crack-prone. So don't let the part get too hot and wait for it to cool down if needed. The exact limits depend on the material, so you have to work according to the spec. Better to stay a bit cooler than to ruin the weld.