Interpass Temperature

The temperature of the joint when the next weld pass is started, controlled to limit both cracking and softening.

Too cold and hydrogen cracking becomes a risk in high strength steel; too hot and the heat affected zone widens and softens further. The qualified procedure states a range, and on armour and 4340 work the range is checked with contact pyrometers between passes rather than assumed. Interpass control is recorded on the weld log that ships with the assembly.