Evaluation of the Mechanical Properties of 15Cr-5Ni Stainless Steel Produced by Direct Metal Laser Sintering

Abstract

This research work examines the mechanical behavior of 15Cr-5Ni stainless steel parts produced by direct metal laser sintering (DMLS). The main objective of this research is to identify the influence of low-temperature precipitation hardening on tensile properties and fracture toughness of DMLS fabricated specimens. Test specimens were fabricated according to ASTM E8/M8 and ASTM E399 standards using EOS M290 laser sintering machine. Following DMLS specimens were subjected to precipitation hardening for an hour at a temperature of 486 °C. To evaluate the influence of heat treatment on mechanical properties of the DMLS produced parts, tension tests and linear-elastic plane-strain fracture toughness tests were performed at the room temperature. Furthermore, microscopic observation of fractured surface was performed to study the failure mechanisms in more detail. The outcomes indicated that the post-DMLS heat treatment improves mechanical properties in the terms of yield stress, Young’s modulus, and ultimate tensile strength. However, this process has a negligible negative effect on the ductility. Moreover, the fracture toughness test results indicated ductile fracture mechanism in the DMLS produced specimens while the specimens were subjected to precipitation hardening demonstrates brittle fracture.