Tensile and Fatigue Response of the Laser Powder-Bed Fused Ti-6Al-4V Alloy at High Temperature Conditions

Abstract

Abstract The purpose of this study is to investigate the thermal and mechanical properties of L-PBF processed specimens at room and elevated temperatures while varying the loading conditions. The study covers finite element (FE) modeling of the tensile and fatigue behavior of the L-PBF processed Ti-6Al-4V specimens at room and high temperatures and corresponding experimental validation. The specimen used for the study is a heat-treated and post-machined standard ASTM sub-size flat dog-bone specimen. The FE modeling for the fatigue analyses is conducted for a load ratio of R = 0.1 and by applying fully-reversed cyclic loads at different frequencies. The high-temperature test condition is obtained by adjusting the convective heat transfer coefficient of surrounding air and emissivity inside the furnace. Results for the von Mises stress, strain, total deformation, fatigue life, the factor of safety, and fatigue limit are obtained at room (22 °C) and elevated temperatures (350 °C and 450 °C). The FE results show that the fatigue life decreases as the load increases. It is also found that the strength and fatigue life decrease as the temperature increases due to the development of thermal stress. The performance of the L-PBF processed specimens is also compared to the conventionally manufactured Ti-6Al-4V parts under the same magnitude of load and temperature to outline the differences in strength and fatigue resistance properties. The validation of the FE model is performed by comparing the numerical results with the experimental results under similar operating conditions.