GU Yu-li
,
et al
钢铁研究学报(英文版)
The fracture behavior in the thermo-mechanical fatigue (TMF) of the Nickel-base Powder Metallurgy Superalloy FGH96 was investigated under in-phase (IP) and out-of –phase (OP) loadings at the temperature range from 550℃ to 720℃ and mechanical strain amplitude range from 0.3% to 0.8％. The results show that the FGH96 TMF fracture character is intergranular on the IP samples and transgranular cleavage on the OP samples, at the same strain amplitude, the fatigue life is shorter for the IP than that for the OP samples that is related to crack propagation along grain boundary on the IP samples, the γ′ size is larger in the IP than that in the OP sample, which is related to the bulk diffusion processes accelerated by the tensile strain during the high temperature portion of the IP cycle. Dislocation pairs and stacking faults are main microstructures induced by IP TMF, and they are hindered by the grain boundary, which likely resulted in the crack propagation along the grain boundary in the IP samples.
关键词:
nickel-base superalloy;powder metallurgy;thermo-mechanical fatigue;γ′ size;dislocation
