Formation of the structure, mechanical and tribological properties of high chrome steel by electronic-ion-plasma nitrogen

The purpose of this work is to detect the regularities of the formation of the structure, mechanical and tribological properties of high-chromium steel subjected to complex treatment combining irradiation with a pulsed electron beam and subsequent nitriding in a low-pressure gas discharge plasma using a plasma generator with an incandescent cathode “PINK”. The object of the study was heat-resistant corrosionresistant austenitic steel grade AISI 310. The relevance and practical significance of the research is due to the relatively low level of hardness and wear resistance of steels of this class, which have a wide range of applications in modern industry, including in the rocket and space industry. Irradiation of AISI 310 steel with a pulsed electron beam was carried out at the SOLO installation, subsequent nitriding (the QUINT installation). It was found that irradiation of samples at an electron beam energy density of 30 J/cm2, 200 microseconds, 3 pulses and subsequent nitriding at a temperature of 793 K for 3 hours led to the following changes in mechanical properties. The maximum microhardness reached values of 19 GPa (exceeds the hardness of steel before modification by 11.2 times and the hardness of steel after electron beam irradiation by 8 times). The wear parameter has changed to values k = 0.7 ´ 10 -6 mm3/N ´ m (less than the wear parameter of steel before modification by more than 700 times and less than the wear parameter of steel after electron beam irradiation by more than 750 times). The thickness of the hardened layer is 40 microns. It was found that the samples that have the maximum (90.6 %) content of nitride phases (chromium and iron nitrides) in the surface layer. Shown that after nitriding at a temperature of 723 K in the surface layer of steel, iron and chromium nitrides are formed in the form of nanoscale particles of rounded shape. At nitriding temperatures of 793 K and 873 K, a plate-type structure formed by alternating parallel plates of iron nitride and chromium nitride is formed in the surface layer of steel.