Effect of texture on the fatigue crack initiation of a Dual-Phase Titanium alloy

Abstract

Fatigue indicator parameters (FIPs) can serve as a measure of fatigue crack initiation (FCI) in metals and alloys. FIPs are volume averaged over grains, bands, and sub bands in crystal plasticity (CP) simulation to investigate the influence of texture on FCI under low cycle fatigue. The equiaxed microstructure of Ti–6Al–4V was generated with three different textures: basal, basal/transverse and transverse. FIPs analysis shows that basal texture has the highest FCI resistance, basal/transverse texture has intermediate resistance, and transverse texture has the lowest resistance when tested along plate direction. All textures exhibit a lower FIP when deformed along rolling direction (RD) than that along transverse direction (TD). The interior of the alloys has a larger FCI resistance than the free surface. Further analysis shows a strong relationship between FIP distribution features and damage nucleation characteristics, with basal texture exhibiting the lowest and wider FIP distributions as a result of high resistance to damage and fatigue cracking; in contrast, the transverse texture exhibits intense and narrow FIP and damage nucleation along the grain boundaries (GBs), basal/transverse texture exhibits FIP and damage nucleation with mixed characteristics. The results can be used as a theatrical reference for the fatigue performance design of Ti alloy.

Keywords

• Ti-6Al–4V alloy
• Crystal plasticity: texture
• Cyclic fatigue
• Damage nucleation