Assessment of 316H Stainless Steel Produced by Directed Energy Deposition Additive Manufacturing for High Temperature Power Plant Applications

There is an ever-growing interest across the advanced energy system landscape to produce pressure-retaining components via additive manufacturing processes for power plant service. As such, various ASME boiler and pressure vessel code committees are actively developing code rules that will enable the employment of additively manufactured components for pressure-retaining applications. Establishing the technical basis for such code rules requires a thorough understanding of how additively manufactured materials behave across typical power plant service temperatures as substantiated by material test data. Austenitic stainless steels represent one of the key material systems that are receiving attention for additive manufacturing applications due to their preeminence in traditional product forms across the power generation industry. While a considerable amount of mechanical property data has been generated for additively manufactured austenitic stainless steels to characterize time-independent mechanical performance, very little data is openly available to characterize time-dependent mechanical performance at elevated temperatures. This study will present findings from three separate collaborative research programs focused on the elevated temperature mechanical performance of 316H stainless steel produced using directed energy deposition additive manufacturing. 316H stainless steel builds produced using laser powder directed energy deposition and gas metal arc directed energy deposition were evaluated in various orientations and heat treatment conditions. The generated creep data from all 316H directed energy deposition builds will be compared and evaluated against an extensive collection of creep rupture data from traditional wrought 316H product forms. High fidelity chemical analysis results from each directed energy deposition build will also be presented and evaluated in the context of existing material specification limits and industry best practice chemistry restrictions. Microstructure characterization will also be presented to supplement creep and chemistry results.