Effects of laser irradiations on layers condition in three-layered sheet metals

Stainless-steel SUS430/copper C11000/stainless-steelSUS430 three layered sheets have been exposed to differentnumber of Ytterbium fiber laser irradiations. Fivespecimens are prepared with 0, 10, 20, 30 and 40 laserpasses. The steel and copper layers boundary conditions areevaluated after laser forming and tensile test bymetallography and SEM, respectively. The microstructureof unirradiated SUS430 consists of ferrite and dispersedcarbide particles. Microstructure of specimens with laserirradiation in the HAZ is consisting of martensite andoriented ferrite with smaller grain size. Copper hasmicrostructure of a solid solution of copper containingtwins in all specimens. Boundary of layers of the specimensdoes not show any separation and mixing after laserforming. The reason for this is low penetration depth in thematerial in the HAZ which only includes a small portion ofthe steel layer exposed to the laser. Evaluation of thefracture surface using SEM showed dimples in steel andcopper layers. No separation is found in layers boundary ofthe tensile test specimen.