Sheet metal pieces intended to be welded can be made with weld notches located along one or more edges. A weld notch is characterized by the absence of certain material constituents so that they do not unacceptably contaminate nearby welds. The weld notch can be created by first forming an ablation trench along the sheet metal piece, then separating the sheet metal piece along the formed ablation trench into two separate pieces, at least one of which includes a newly formed and weldable edge.