Stress Relaxation Testing as a High Throughput Method for Assessing Creep Strength in Laser Powder Bed Fusion Processed Ni-Based Superalloys

Ni-based superalloysNi- based superalloy processed by laser beam powder bed fusion (PBF-LB) additive manufacturingAdditive manufacturing (AM) are ideal for high temperatureHigh temperature structural applications in the aerospace and power generation industries due to the increased component complexity afforded by AM. However, conventional creep testingCreep testing limits the rate at which new materials can be produced with AM. To help accelerate the acceptance of AM Ni-based alloysNickel-based alloys for high temperatureHigh temperature applications, methods for high throughput creepCreep evaluation are needed. The stress relaxationStress relaxation test has potential to hasten the development and validation of PBF-LB Ni-based structural alloys by assessing a wide range of creepCreep rates relevant to service conditions with a single test. In this work, alloy Ni230, a gas atomized powder derivative of Haynes 230Haynes 230, and variant thereof containing added TiC are assessed. Each material was subjected to a limited subset of conventional creepCreep tests accompanied by stress relaxationStress relaxation tests. Following the calculation methodology described herein, stress relaxationStress relaxation tests predict creepCreep rates and rupture times that align well with conventional creepCreep test results. Stress relaxationStress relaxation tests also reveal features of microstructural characteristics and evolution which are not readily apparent with other experiments. Several advantages and challenges with stress relaxation testingStress relaxation testing are discussed.