Comparative study of structural phase condition and mechanical properties of Ni–Cr(X) и Fe–Cr(Х) heat-resistant alloys obtained using additive technologies

The comparative study covers the features of formation, thermal stability of structure and mechanical properties of heatresistant Ni and Fe based alloys obtained using additive technologies (AT) by direct metal laser sintering, selective laser melting. It is found that alloys obtained by direct metal laser sintering have a cellular structure formed with small pores up to 200 nm in size, in contrast to alloys obtained by selective laser melting having elements with a globular and lamellar morphology and not completely melted areas as well as large pores about 5 μm in size. The study reveals a possible effect of nanophase hardening due to the presence of nanosized particles of chromium silicides in the material. A comparative analysis of the mechanical properties of studied materials is carried out. It is shown that the iron-based alloys have higher strength and lower ductility compared to nickel alloys. All studied samples obtained by selective laser melting demonstrate higher strength characteristics in comparison with alloys obtained by laser metal deposition. As a result of short-term annealing at a temperature of 900–1000 °C for 1 h leads to a significant reduction in the plasticity and strength of iron-based AT alloys during tensile and compression tests at room and elevated temperatures. During compression tests at t = 900 °C, iron-and nickel-based alloys obtained by laser metal deposition have similar strength characteristics. Unlike iron-based alloys, additional annealing of nickel-based AT alloys has virtually no impact on its strength properties.