Interpass Temperature
The interpass temperature refers to the temperature of the parent material in the joint area immediately prior to the start of the next weld bead in multi-pass welding. It controls the metallurgical microstructure in the heat-affected zone and prevents excessive hardness peaks.
Interpass temperature is the temperature of the base material between two weld beads before you lay the next pass. If you let it get too high, the structure can overheat and you get hard, crack-prone spots. If it's too low, the previous bead cools down too much, which can also cause problems. Especially with higher-strength steels, you have to watch out and keep the temperature under control. You can measure it best with a thermochromic crayon or a contact thermometer right at the seam.