I'd call it a forging lap actually. Two forged layers of metal not bonded together (in this case) or a single piece of metal with an inclusion flattened inside and not fused.
A cold shut is more of a foundry defect where two fronts of molten metal in a mold flow together, touch, but never fuse together leaving a tight but unbonded line or seam.
Not trying to be picky but I hve 26+ years of this stuff stuck in my head <g>. My day job is as NDT Lab manager for
www.dankoarlington.com, but by night you all know me as "Proffessor Strop" <g>.
Tony