Fatigue behavior of Ti6Al4V alloy components manufactured by selective laser melting subjected to hot isostatic pressing and residual stress relief

Fatigue behavior (R-epsilon = -1) of HIPed and stress relieved Ti6Al4V alloy specimens produced by selective laser melting (SLM) was analyzed and compared resulting that the hot isostatic pressing (HIP) process caused a microstructural transformation decreasing the hardness and monotonic properties leading to cyclic softening that not allowed fatigue strength to increase. A bilinear behavior in the elastic strain-fatigue life curve was observed due to the decrease of the Young's modulus during the cyclic elastoplastic tests, consequence of subgrains formation. The Smith-Watson-Topper and total strain energy density models adjusted by the bilinear behavior showed a good concordance between predicted and experimental fatigue lives in notched samples.

Automated summary

The study found that the hot isostatic pressing process caused microstructural transformation in Ti6Al4V alloy specimens, leading to decreased hardness and monotonic properties, resulting in cyclic softening and no increase in fatigue strength. Bilinear behavior in the elastic strain-fatigue life curve was observed, with good concordance between predicted and experimental fatigue lives shown through adjustment using models.