Possibilities of Additive Technologies for the Manufacturing of Tooling from Corrosion-Resistant Steels in Order to Protect Parts Surfaces from Thermochemical Treatment

Abstract

The structure and physical–mechanical properties of products made from powders of corrosion-resistant steel 12X18H10T by the laser-beam powder bed fusion (LB-PBF) and subsequent ion-plasma nitriding in the work were investigated. Comparative studies of the physical mechanical properties of specimens made by the LB-PBF and conventional method from steel of the same grade were carried out. The density of the specimens and the coefficient of linear thermal expansion (CLTE) after the LB-PBF are almost the same as those of the conventionally manufactured specimens. Our analysis of the obtained dilatograms in the temperature range from 20 to 600 °C showed that the CLTE of steel after the LB-PBF is within acceptable limits (18.6 × 10−6 1/°C). Their hardness, tensile strength, yield strength and elongation are higher than those of a conventionally manufactured specimen. The phase composition and structure of specimens of steel 12X18H10T made by the LB-PBF after the process of ion-plasma nitriding were investigated. The obtained results show that the mode of ion-plasma nitriding used in this case (stage 1—570 °C for 36 h; stage 2—540 °C for 12 h) does not lead to deterioration of the characteristics of the selected steel. A technological process for the manufacture of modified tooling from 12X18H10T steel by the LB-PBF was developed. It protects the surfaces that are not subject to nitriding and makes it possible to obtain a uniform high-quality nitrided layer on the working surface of the part made from spheroidal graphite iron.