Computational Modeling of Nanosecond Laser Ablation of Ti-6Al-4V

Abstract

Abstract Ti-6Al-4V is an alpha-beta titanium alloy having excellent strength, low modulus of elasticity, high corrosion resistance, good weldability and heat treatability. Consequently, it is the most commonly used titanium alloy with a wide use for applications in aerospace, automotive, and biomedical industries. However, Ti-6Al-4V is very difficult to be machined using traditional manufacturing processes. Laser machining is one nontraditional manufacturing process to machine Ti-6Al-4V. However, the laser-machined surface usually experiences phase transformation during the laser machining process because of the heating and cooling in laser machining. In this paper, the commercial Finite Element Method (FEM) software package ABAQUS is employed to assess the effect of nanosecond laser machining conditions and operating temperature on crater size, phase transformation in the Heat Affected Zone (HAZ), and residual stress distribution in laser machining of Ti-6Al-4V. The energy levels: 60mJ, 121mJ, 201mJ, 309mJ, 407mJ, 621mJ, 667mJ were tested. For the predictive modeling, three energy levels: 1000mJ, 2000mJ, and 4000mJ were tested. The phase transformation of Ti-6Al-4V at different temperatures was investigated to see material property change. The temperature used were: 200°C, 400°C, 600°C, 800°C, and 100C. Phase transformation kinetics is used to model the phase transformation of Ti-6Al-4V in laser machining process and rule of mixtures is employed to describe flow stress. Based on the results, the increasing the temperature will induce more HAZ. This research can provide insightful guidance for laser machining of Ti-6Al-4V.