Advanced Heat Treating Research at CHTE

In this presentation, the current heat treatment research projects at CHTE will be introduced, including surface treatment modeling, post-processing of additively manufactured parts, and austempering. CHTE continuously works on the simulation of thermochemical surface treatments and develops predictive software models for carburizing and nitriding (CarbTool and the NitrideTool). With the input process parameters for the gas atmosphere, temperature, and time the carbon or nitrogen concentration profiles are calculated, which allows the case hardness and case depth predictions. In addition, to understand the response of additively manufactured (AM) parts to post processing heat treatments, steels such as 20MnCr5, AISI 8620, M2 are selected to fabricate the AM parts by selective laser melting (SLM) and subsequently heat-treated side by side with the wrought parts. The microstructure and mechanical properties before and after heat treatment are experimentally determined for both AM and wrought parts. Austempering is typically conducted in molten salt to form bainite. Molten salts have raised environmental concerns. CHTE is working to develop an alternative quench process to form bainite without using molten salt. Austempering in a fluidized bed, hot oil, high pressure gas or hot isostatic press is being investigated.