Physical-based methodology for prediction of weld bead characteristics in the Laser Edge Welding process

Abstract

A comprehensive physical-based methodology is introduced to predict weld bead properties in the Laser Edge Welding (LEW) process. Laser edge welding of AISI 316L stainless steel thin sheets are conducted to investigate the behavior of geometrical, mechanical and metallurgical properties of the weld bead. The effect of significant processing parameters including the laser power, speed and focal distance are considered. The method however, utilizes a set of physical-based contour plots to predict the trend of weld characteristics using the heat input and power density. A novel combined physical parameter is also introduced and optimized to indicate the exact quantitative effectiveness of each physical and processing parameter. The developed approach is utilized to analyze a broad range of weld bead characteristics. First, weld bead geometrical characteristics such as weld width, penetration and distortion are studied. The physical-based method revealed that the power density has a significant effect on the weld penetration-to-width ratio while distortion is governed by the heat input. Variations of the fracture load are analyzed based on the corresponding combined parameter. Interestingly, a greater penetration-to-width ratio results in a higher fracture load. Finally, microstructural evolutions are investigated in three main regions, including the top, middle and bottom of the weld bead. A skeletal ferrite phase is observed in the mid-zone, which increases with increase of power density. The presented methodology can be applied to a broad range of other laser materials processing techniques to obtain insightful process design tips in order to achieve tailor-made properties.