An investigation of the effect of pulse frequency in laser multiple-layer cladding of stainless steel

The consolidation of metal powder onto a solid substrate using a laser beam allows fusion of the build material to be realised and fully-dense walls or surfaces, suitable for rapid prototyping and tooling applications, to be fabricated. The final wall geometry and microstructure of metals deposited in this way are determined in part by the pulse frequency of the laser beam used. A 1.2 kW CO2 laser, operating over a range of different pulse frequencies is used to investigate this effect. Microstructural characterisation of multiple layers of consolidated 316L steel revealed a coarser, but less porous austenitic structure when using a pulsed beam. The final hardness of the steel increased with pulse frequency, but was not constant throughout the wall, and the surface roughness varied little.