Implementation of Additive Manufacturing (AM) to turbine engine advancement has been stifled due to low confidence in the reliability and repeatability of structural integrity. Specifically, fatigue reliability has been the key factor limiting wider adoption of AM to critical turbine engine parts. Historical data has shown that the fatigue life of AM parts are reduced compared to conventional manufacturing. In depth process parameter development and optimization have been carried out to address key factors in fatigue performance such as porosity, residual stress, and microstructure homogeneity. However, the progress in AM has not reached the level of confidence necessary for implementation to manufacturing critical turbine engine parts. The submitted abstract demonstrates a post process application that improves the fatigue properties for Stainless Steel 316L AM parts. The 316L AM coupons were made with Laser Powder Bed Fusion (LPBF) and Binder Jetting AM processes. The AM coupons were surface treated with a proprietary nitrocarburizing process. Comparisons between untreated (baseline) and surface treated specimens were made by conducting accelerated fatigue testing. The accelerated testing method is a resonance based vibrating bending test that gathers fatigue data >80X faster than standard methods. The results of the fatigue tests show that using a nitrocarburizing surface treatment for both LPBF and Binder Jet 316L leads to a stress amplitude increases as high as 53% for fatigue life out to 10 million cycles. Future applications consider nickel alloys for next generation aerospace applications.
Learning Objectives:
Upon completion, participants will be able to understand how a surface treatment method can enable a broad adoption of additive manufacturing to the Aerospace Industry.
Upon completion, participants will be able to explain how nitrocarburzing works while seeing the benefits of an accelerated testing method for rapidly assess the viability of additive manufacturing processes.
Upon completion, participants will be able to comprehend the time and cost value of a new accelerated testing method motivated by the need for high throughput iteration for AM innovation.
