Precipitation of α Phase and Mechanical Properties of TB6 Titanium Alloy Prepared by Selective Laser Melting

Abstract:

The influence of aging temperature on the microstructure and mechanical properties of TB6 titanium alloy fabricated via selective laser melting (SLM) was investigated. The results show that the microstructure of SLMed TB6 titanium alloy predominantly consists of columnar β phase and equiaxed α phase, and the precipitation of lamellar or granular α_P phase and grain boundary α_GB phase occurs after solution treatment and aging. With the increase in aging temperature, the α phase is gradually diminished in size, the volume fraction of lamellar α phase is decreased, and the amount of granular α_P phase is increased. The tensile test results indicate that as the aging temperature increases, the tensile strength of the material decreases while its plasticity is significantly improved. The tensile strength of samples decreases from 1386.22 MPa (aged at 520 ℃) to 1129.00 MPa (aged at 560 ℃), whereas its elongation increases from 7.1% to 10.5%. It is concluded that changes in the morphology and size of the α phase significantly impact the strength and plasticity of the alloy. Reducing the volume fraction of lamellar α_L phase and increasing that of granular α_P phase improve the strong-plasticity matching. Elevating the aging temperature can decrease the volume fraction of lamellar α_L phase and enhance the plasticity of the material.