Effect of Surface Finish and Temperature on Low Cycle Fatigue Behavior of GRCop-42

Abstract

This study investigates the impact of various surface finishes on the low cycle fatigue (LCF) properties of laser powder bed fusion GRCop-42. The evaluated surfaces include as-built, machined, and chemically polished finishes (1.0% and 2.0% ranges). LCF life of polished GRCop-42 was assessed at cryogenic (−195°C), ambient, and elevated temperatures (200°C, 400°C, 600°C, and 800°C) across three strain ranges. Results indicate that surface finish has minimal impact on LCF life. Stress across different strain levels showed minimal effect of surface finish on cyclic hardening/softening. Cryogenic temperatures led to cyclic hardening followed by stabilization, while ambient and 200°C temperatures showed initial hardening followed by softening. At 400°C and above, specimens displayed continuous cyclic softening. Fractography showed that surface finish impacts plastic deformation: as-printed and polished surfaces had brittle fractures, while machined specimens were ductile. Specimens at cryogenic and ambient temperatures exhibited brittle fractures, whereas those at elevated temperatures showed plastic deformation and microcracks.