Ti-22V-4Alにおける疲労き裂発生・進展特性

抄録

To investigate the fatigue crack initiation and propagation properties of Ti-22V-4Al, uniaxial fatigue tests and surface observation were carried out. As a result of surface observation, the crack initiation life of each crack was clarified. The cracks initiated at N = 2000 to 8000 cycles. Based on the crack initiation life of each crack, the tendency of crack initiation was investigated using probability paper. As a result, it was shown that the crack initiation life follows the lognormal distribution. Based on the crack propagation observation results, the relationship between the crack growth rate da/dN and the stress intensity factor range ΔK was investigated. As a result, in the small ΔK region, the dispersions of each crack was large. However, with the increase in ΔK, the dispersions became smaller and showed a certain width. Comparing with the same material with different heat treatment samples, da/dN-ΔK relations in large ΔK regions show similar value. So it suggests that crack propagation resistance may not be affected by the precipitation amount of α phase in this material.