INFLUENCE OF SELECTIVE LASER MELTING WITH ADDITIONAL REMELTING OF RECRISTALLISED LAYERS ON THE STRUCTURE AND PROPERTIES OF HEAT-RESISTANT STEEL 15X25T

Research into the selective laser melting (SLM) process has led to a significant improvement in the quality of synthesized objects. With incorrect selection of process modes during the production of heat-resistant steel products, various defects (pores, cracks, lack of fusion) may occur, which significantly reduce the mechanical properties of the material. Elimination of defects in selective laser melting can be achieved by optimizing the laser beam processing mode. As such a processing strategy, it is proposed to re-melt the formed roller or heat-treat it with laser radiation without melting the metal during a second laser pass without powder feed. The study of the influence of repeated laser remelting of crystallized tracks on the microstructure and mechanical properties of parts made from powders of corrosion-resistant and heat-resistant steels is currently relevant. This article presents studies of the influence of growth modes of heat-resistant steel 15X25T samples on the structure and mechanical properties. The mechanical properties, heat resistance and corrosion resistance of 15Kh25T steel samples obtained by SLM with additional remelting of previously recrystallized tracks were investigated. It was shown that the obtained material surpasses the deformed semi-finished product made of 15Kh25T steel in a set of mechanical properties. Significant residual stresses at a level of 236 MPa were revealed in 15Kh25T steel samples. The use of additional remelting allows this level to be reduced to 108 MPa. The results of microstructural analysis of the surface layer of 15X25T steel samples obtained by SLM with additional laser remelting of recrystallized tracks (laser power 135 W and scanning speed 450 mm/s) revealed a decrease in the surface roughness of the sample Rz from 62 to 12 – 15 μm.