Influence of heat treatment on residual stress of Ti-6Al-4V alloy by laser solid forming

The residual stress of Ti-6Al-4V alloys by laser solid forming was measured adopting the standard strain gauge technique involving hole drilling method. Sample treatments were divided into three conditions, that is as deposited, annealing and solution aging treatment. The results indicate that the residual stress exhibits the similar distribution along the laser scanning direction (σ_Y) and normal to the scanning direction (σ_Z). At the location of laser starting scanning, the stress is lower. The largest stress is the compressive stress at the center position and transformed to the highest tensile stress at the location of ending of laser scanning. It can also be found that the residual stress exhibits bigger compressive stress near the substrate, and with increasing of the cladding layer, it develops to lower tensile stress at the top of sample. After annealing treatment, the stress decreases averagely σ_Y for 59.8% and σ_Z for 72.3%, respectively. After treating by solution aging, the stress decreases averagely σ_Y for 64.7% and σ_Z for 67.8%, respectively. Heat treatment was found to relieve and adjust the residual stresses of laser solid forming Ti-6Al-4V alloy effectively.