| Title |
Microstructural Influence on the Fatigue Behavior of Al - Li 8090 Alloy |
| Authors |
박기종(K . J . Park); 박찬경(C . G . Park); 장영원(Y . W . Chang); 이종수(C . S . Lee) |
| Abstract |
The present research was performed to investigate the effect of precipitates on the fatigue properties of 8090 Al-Li alloy. By applying different heat treatment paths, two types of microstructures were produced : one with the δ` phase dominant microstructure and the other with δ` + S` microstructure. It was observed that both the fatigue crack initiation resistance and fatigue crack propagation resistance of δ` microstructure were considerably higher than those of δ` + S` microstructure. Excellent resistance for fatigue crack initiation in δ` microstructure was mainly attributed to the extrinsic nature such as crack path tortuosity and higher level of crack closure, as well as to the intrinsic nature of greater slip reversibility in δ` microstructure. However, δ` + S` microstructure showed greater intrinsic resistance for crack propagation at intermediate ΔK region, probably due to the effect of slip dispersion by the presence of S` phase. It was also observed that the relative amount of crack closure was maximum at the near threshold regime and decreased rapidly as ΔK increased. |