Tensile stress-strain curves of the selected samples including the raw (non-welded) double-layer sheet, the sample welded by the thread tool in two passes from the Al side with rotational and traversing speeds of 800 rpm and 12 mm min^‑1 (sample number 5), and the sample welded by the conical tool in one pass from the Cu side with rotational and traversing speeds of 800 rpm and 12 mm min^‑1 (sample number 7).