Any opinions on this would be helpful, I know what code (D1.1) says as far as what temps should be for welding and tacking etc . I was just wondering how you handle this. Our shop is in the Dakotas right now in the mornings it is -12. A person brings in steel from outside and tacks basically immediatly on these parts. Question is ---- are the parts scrap??? Reworkable? ?? Have we cracked the base mat.(.375 thk A572) in the micro structure? Can we grind out the tacks and just start over again or are parts junk???? Any info would be appreciated. Thanks in advance.
The parts are not junk. You need Eng/QC to disposition the problem, grind the tacks, do some NDE to verify the absence of cracks (most likely not there) and recover the assembly. A572 is actually a quite resilient material. But a lot depends on whether there will be an an increased risk of cracking due to other factors, such as part restraint etc.
I agree with JS- If the tacks are in the root of a full penetration weld, I'd suggest grinding them out and starting over. If the tacks are in fillet weld areas and not visually cracked, I'd likely grind smooth, MT if possible, and continue.