Effect of constraint on fracture performance of Ti6Al4V alloy fabricated by laser powder bed fusion

Abstract

Laser powder bed fusion (LPBF) is increasingly being used as an alternative to traditional manufacturing in the aerospace and biomedical industries. The effect of constraint on fracture performance is a crucial issue in assessing the integrity of engineering applications. This paper aims to better understand the fracture performance of Ti6Al4V components with different constraint levels produced by LPBF. Fracture toughness tests were performed on compact tensile (CT) specimens with varying crack length and specimen thickness. The results show that the fracture toughness decreases with increasing crack length, while the fracture toughness shows a large fluctuation with specimen thickness because of LPBF manufacturing defects. Both in-plane and out-of-plane constraint effects of a crack subjected to mode-I loading are analyzed by three-parameter K-T11-T33 method. A correlation line between fracture toughness and normalized T11 stress is established, which can be used to transform fracture properties of specimens with different constraint levels.