Microstructure, deformation and lifetime of alloy 617B - experiences from different heat treatments and heats

The present work summarizes experiences with Alloy 617B from different heat treatments and heats investigated at Fraunhofer IWM. For this purpose, different batches of Alloy 617B are compared with respect to chemical composition, grain size, and precipitation state. Moreover, results from low cycle fatigue tests at different strain rates with and without hold times are presented, giving impressions about the viscoplastic material properties and lifetime as a function of the material condition. Further investigations comprise fatigue crack growth measurements and fractographic analysis for the characterization of the prevailing damage mechanisms.