Investigation on laser engineered net shaping of multilayered structures in H13 tool steel

Laser engineered net shaping process is widely used to build multilayered structures for critical applications by melting and solidification of metallic powders in a layer by layer manner using a focused laser beam. An a-priori estimation of the influence of laser beam power and scanning speed on the layerwise build dimensions, thermal cycles, and mechanical properties is requisite in laser engineered net shaping process. We present here a three-dimensional heat transfer model to estimate the temperature field and layer profile in single line multilayer depositions of H13 tool steel. A novel approach is undertaken to account for the laser beam energy input to the substrate and the depositing powder materials considering the attenuation of the beam power. The computed build profiles are validated with the corresponding experimentally measured results. The computed cooling rates show a reducing trend from the bottom to the top layers while that in the transformation temperature range tend to increase toward the top layer. The measured hardness shows a gentle reducing trend from the top to the bottom layers but exhibits a relatively steep increase in the layers near to the substrate.