Experimental investigations on spatial and temporal laser irradiations in pulsed laser forming of thin metal sheets

Abstract

This article presents investigations on temporal- and spatial-pulsed laser irradiations on thermal sheet forming of 304 austenitic stainless steel sheets using a fiber laser. A response surface model was developed to predict deformations of thin sheets irradiated by a pulsed laser considering laser power, scan speed, spot diameter, pulse frequency, and duty cycle as inputs based on experimental data obtained following a central composite design of experiments. The results showed that bending deformation increased with increasing laser power and duty cycle and with decreasing scan speed and spot diameter. However, an optimum value of the pulse frequency was found for maximum deformation. Adaptive neuro-fuzzy inference system-based models were also employed to predict deformations in pulsed laser forming. The prediction accuracy of the developed models was found to be good. Then, the desirability function approach of an optimization technique was employed to determine the optimum process parameters corresponding to maximum and minimum deformations. A comparison of the pulse and continuous wave mode of laser forming for constant laser energy input revealed that the pulsed mode of laser forming is more effective in terms of generating a larger amount of deformation for both two- and three-dimensional shapes forming. Pulsed laser formed samples with surface melting were found with modified finer grain microstructures which could be beneficial for specific applications.