It is also worth mentioning that fusion of the faying surfaces of the parent components is not necessary for weld bead formation. In some welding processes, the faying surfaces are fused with the application of heat to get the weld bead, while in other processes, weld bead can be obtained without melting the faying surfaces. On the basis of whether base materials are fused or not, welding processes can be broadly classified into two groups—solid state welding and fusion welding.
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