MODE INFLUENCE OF SELECTIVE LASER IMPACT UPON POROSITY OF SAMPLES OF COBALT, CHROMIUM AND MOLYBDENUM POWDERS

Abstract

The purpose of this investigation consists in the analysis of possibility to obtain products by means of the SLP method using powders of cobalt, chromium and molybdenum having considerable difference in melting temperatures of cobalt (1768ºC), chromium (2130ºC) and molybdenum (2890ºC), density, thermal conduction and solving for the optimum technological modes of powder composition melting to obtain samples with lower porosity. The investigation methods include methods of physical material science. Investigation results and novelty: a procedure for obtaining a powder composite of the cobalt-chromium-molybdenum system for selective laser melting is developed. There are carried out experimental investigations on the selection of optimum technological modes for the layer-by-layer laser melting of a cobalt-chromium-molybdenum alloy of powder composition. A method for layer-by-layer laser synthesis for the solution of a principle matter – possibility for the synthesis of the products of cobalt chromium and molybdenum powders having a considerable difference in melting temperatures, density, heat conductivity and so on. The investigations of model alloy samples of cobalt-chromuim-molybdenum system obtained through the method of layer-by-layer laser synthesis on optimized technological modes through the methods of scanning electronic microscopy allow defining sample porosity. The generalization of obtained numerical and experimental investigation results and definition of essential conditions for selective laser melting allow optimizing modes and parameters of the synthesis. Conclusions: the optimum modes of selective laser melting for obtaining the samples with the powder composition of 66 mas. % Co, 28 mas. % Cr, 6 mas.% Mo through the method of selective laser melting with minimum porosity are: laser capacity P=100Wt, scanning rate v=350mm/s, modulation 5000Hz, scanning pitch s=0.1mm, layer thickness h=0.03mm, melting process takes place in protective argon environment.