Effect of microstructure on fatigue crack tip field of laser melting deposited Ti–5Al–5Mo–5V–1Cr–1Fe titanium alloy

¹ Institute of Solid Mechanics, Beihang University (BUAA), Beijing 100191, China
² National Engineering Laboratory of Additive Manufacturing for Large Metallic Components (Beihang University), Beijing 100191, China
³ Engineering Research Center of Ministry of Education on Laser Direct Manufacturing for Large Metallic Components, Beijing 100191, China
⁴ School of Materials Science and Engineering, Beihang University, Beijing 100191, China

^* Corresponding author: rbao@buaa.edu.cn

Abstract

In this paper, experimental and simulated investigations were carried out to understand the effect of microstructure on the fatigue crack tip strain field of laser melting deposited Ti–5Al–5Mo–5V–1Cr–1Fe titanium alloy. The mechanical properties of the laser melting deposited material corresponding to different microstructure zones were measured by digital image correlation method under in-situ static stretching, and the results indicate that the direction of primary α lamellas has great influence on the mechanical property of each grain. The crack tip strain fields considering the influence of material microstructure under constant amplitude conditions were measured, and the strain field of plastic zone has significant difference. Crystal plasticity finite element simulation of the static tensile and crack tip field considering the microstructure effect had been conducted and compare with experiment results. The simulation results are in good agreement with the test results in both the static tension strain field and crack tip strain field.