About this Abstract |
Meeting |
Superalloys 2024
|
Symposium
|
Superalloys 2024
|
Presentation Title |
Retardation and Acceleration of Dwell-fatigue Crack Propagation in Ni-base Superalloys: Experimental and Numerical Investigations on CMSX-4 and IN718 |
Author(s) |
Shiyu Suzuki, Hayato Matsuoka, Qihe Zhang, Zhiqi Chen, Itsuki Sasakura, Motoki Sakaguchi |
On-Site Speaker (Planned) |
Shiyu Suzuki |
Abstract Scope |
Effect of tensile dwell on crack propagation under subsequent fatigue loading during dwell-fatigue crack propagation in Ni-base superalloys was investigated using a single crystal superalloy, CMSX-4, and a wrought superalloy, IN718. Crack propagation tests with single tensile dwell introduced during pure fatigue loading under various conditions of stress intensity and dwell time were conducted at 900 °C and 650 °C for CMSX-4 and IN718, respectively. In CMSX-4, fatigue crack retardation occurred after the tensile dwell, which was attributed to stress relaxation induced by creep deformation during the dwell and the resultant residual compressive stress during the subsequent fatigue loading. Fatigue crack propagation rate after the tensile dwell was quantified by evaluating effective stress intensity factors based on the residual compressive stress field obtained by finite element analysis. In IN718, acceleration of the fatigue crack propagation occurred after the tensile dwell at high Kmax values whereas the retardation occurred following temporary acceleration after the dwell at low Kmax values. The acceleration was attributed to grain boundary (GB) damage caused by oxygen diffusion along the GBs induced by high stress near the crack tip during the tensile dwell. The transition from the crack retardation to the acceleration in IN718 was rationally explained based on a size relationship between the stress relaxation area and the GB damage zone around the crack tip caused by the tensile dwell. |
Proceedings Inclusion? |
Definite: At-meeting proceedings |