Strengthening of Austenitic Steel 316 Alloy by Incorporating ZrO2 Particles via Mechanical Alloying and Vacuum Hot-Pressing

This study examines the influence of ZrO2 on austenitic stainless steel 316 (ASS 316). Following the addition of varying weight percentages (0, 1, 2, and 3) of ZrO2 to ASS 316 powder, the samples were ball-milled for a duration of 30 h and then subjected to vacuum hot-pressing (VHP) for consolidation. After 30 h of milling, 2 and 3 wt.% ZrO2 alloys showed diffraction patterns of Zr phases other than the face-centered cubic phase. Nanocrystalline ZrO2 interacted with ASS 316, which resulted in the formation of a Zr phase. Based on the findings obtained from X-ray diffraction (XRD), the Zr phase d-spacing value was determined to be 2.478 Å, which corresponds to the (220) plane configuration. The d-spacing value of the Zr-rich phase observed in the XRD analysis was comparable with the interplanar spacing of 2.565 Å, as revealed by a transmission electron microscopy examination. Following milled-powder consolidation, additional Cr-O peaks were discovered in each of the four different alloy systems. It was noted that the Cr-O peak was present in all four alloys at 2θ angles = 40.36° and 44.87°. The highest hardness achieved by alloy A3 with 3-wt.% ZrO2 was 642.22 HV as determined by the Vickers hardness. This value was approximately 28% greater than that of ASS 316 without ZrO2.