Novel indicators for spatter occurrence in laser lap welding of Zn-coated steels

摘要

The present work proposes two physics-based indicators for predicting spatter occurrence in laser lap welding of zinc-coated steels. The 1st indicator, Zout, given by Equation (1), evaluates the zinc outgassing load in the process by calculating the amount of zinc vapor generated to be outgassed and divided by the keyhole opening area. The 2nd indicator, Z_p, given by Equation (2), measures the keyhole rear wall vulnerability with respect to zinc vapor jet pressure. It calculates the keyhole rear wall surface tension, multiplied by molten pool volume and divided by the zinc vapor jet pressure. A spatter-free process window requires both indicators to be less than their corresponding critical values as shown in Figure 1. The proposed indicators can be used to evaluate proposed laser weld schedules and process for spatter occurrence.