Finite Element Analysis and Experimental Investigations on Laser Bending of AISI304 Stainless Steel Sheet

AbstractLaser bending is a thermal forming process, where a sheet metal gets bent due to residual stresses induced by a controlled defocused laser beam. The present paper deals with the deformation of stainless sheet in laser bending process under temperature gradient mechanism. Finite element simulation was carried out to determine the temperature field and deformation of the sheet metal for different laser powers. Bending angle was found to increase nonlinearly with the increase of laser power up to a certain value of the latter. Bending angles calculated by finite element method were found to be in good correlation, when compared with the analytical and experimental results. After a certain value of laser power, the rate of change of bending angle was decreased, which is called the saturation power. Laser bending process was also investigated beyond the surface melting temperature. After saturation zone, bending angle was seen to increase due to a further increase of laser power and surface melting. Temperature fields of the laser bent samples in different zones were investigated through numerical simulations. Metallurgical changes of the samples for different processing regions were also studied using the scanning electron microscopy and Vickers’ microhardness tester. For stainless steel samples, there was no microstructural change in the region before saturation. After saturation zone, surface microstructure got refined due to surface melting of a thin layer and subsequent rapid quenching. Microhardness of the samples at different processing zones was measured using Vickers’ microhardness tester. Average microhardness was found to increase from normal deformation zone towards the melting zone. The results are helpful to identify the optimum processing conditions for laser bending process under temperature gradient mechanism