Application of response surface methodology in describing the residual stress distribution in CO2 laser welding of AISI304

Laser welding is a low-distortion welding process. Despite this advantage some detrimental residual stresses are still introduced during the process, which reduce the service life of the welded component. Therefore, it is important to estimate the magnitude and distribution of the residual stress. This study aims to create mathematical models to determine the relationship between laser welding parameters and the magnitude of the residual stress at different locations by using response surface methodology. In this study, the process input parameters are laser power, travel speed and focal point position. Laser butt-welding of AISI304 plates joints were investigated using a 1.5 kW continuous wave CO2 Rofin laser as a welding source. Incremental hole-drilling method was employed to measure the magnitude and the distribution of the maximum residual stress. The experiment was developed using a three-factor, five-level central composite design with full replication. Analysis of variance and other adequacy measures were employed to check the adequacy of the developed models using the statistical package Design-Expert. Twenty-one models were developed to demonstrate the magnitude and distribution of the residual stress. The main effect of each factor and the interaction effect with other factors were determined quantitatively and presented graphically.