An investigation of the effect of cryogenic treatment on the microstructure, mechanical and wear properties of maraging steel by selective laser melting

Selective Laser Melting (SLM) is a 3D production method that melts and combines metal powder using intensive laser light. Samples of 1.2709 maraging steel samples produced with SLM were used in this study. Cryogenic heat treatment is an application that complements conventional heat treatment by cooling the materials to a low temperature (-196 °C) to obtain desired mechanical and microstructural properties. In this study, the effect of cryogenic treatment on the mechanical properties and abrasion behavior of maraging steel manufactured with SLM and heat-treated were examined. During the study, steel samples were subjected to different treatments including solution treatment (940 °C / 2h), aging heat-treatment (520 °C / 6h) and cryogenic treatment (-196 °C / 12-hour / 24-hour / 36-hour / 48-hour). Wear, hardness, and tensile tests were applied to the samples at each heat treatment stage; structural characteristics were examined through characterization analyses (X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), and Energy Dispersive Spectroscopy (EDS)).Thanks to the obtained experimental data, the effects of cryogenic treatment on the age-hardened samples were compared with the properties of 1.2709 steel reported in the literature. The test results show that the hardness value obtained in the samples subjected to heat treatment and cryogenic treatment is approximately 50 HRC. It shows that the highest wear resistance was obtained in the samples subjected to cryogenic treatment for 36 hours after heat treatment. The highest tensile strength value was determined as 1788 MPa on the samples that were cryogenically treated at -196 °C for 24 hours.