The Importance of New Heat Treatment for the Creep Properties of High Strength Superalloys Produced by Selective Laser Melting

Selective laser melting (SLM) of high strength superalloy can reduce the overall production time and cost of gas turbine components as well as enabling more efficient designs. These advantages can however be minimized by the reported undesirable microstructure that can result in poor high temperature creep performance. The as-SLM microstructure can contain, for instance, smaller grain size and defects not normally found in the conventionally casted superalloys. Applying conventional heat treatment scheme can produced a different, and very often, inferior microstructure for creep resistance. In this presentation, we are reporting our studies on the post heat treatment schemes for a few superalloys that produced several features favorable to creep resistance to help revising the creep properties. We demonstrate that by significantly altering the heat treatment schemes, the microstructure can be closer to that from the conventional process, increasing creep life significantly. This presentation aims to highlight the needs of developing and defining new heat treatment standards specifically for additively manufactured superalloys for aerospace applications.