| Autor: |
Xing LL; School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China., Zhang WJ; School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China., Zhao CC; Jihua Laboratory, Foshan 528000, China., Gao WQ; School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China., Shen ZJ; School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China.; Arrhenius Laboratory, Department of Materials and Environmental Chemistry, Stockholm University, S-106 91 Stockholm, Sweden., Liu W; School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China. |
| Abstrakt: |
Laser powder bed fusion (LPBF) is being increasingly used in the fabrication of complex-shaped structure parts with high precision. It is easy to form martensitic microstructure in Ti-6Al-4V alloy during manufacturing. Pre-heating the powder bed can enhance the thermal field produced by cyclic laser heating during LPBF, which can tailor the microstructure and further improve the mechanical properties. In the present study, all the Ti-6Al-4V alloy samples manufactured by LPBF at different powder bed temperatures exhibit a near-full densification state, with the densification ratio of above 99.4%. When the powder bed temperature is lower than 400 °C, the specimens are composed of a single α' martensite. As the temperature elevates to higher than 400 °C, the α and β phase precipitate at the α' martensite boundaries by the diffusion and redistribution of V element. In addition, the α/α' lath coarsening is presented with the increasing powder bed temperature. The specimens manufactured at the temperature lower than 400 °C exhibit high strength but bad ductility. Moreover, the ultimate tensile strength and yield strength reduce slightly, whereas the ductility is improved dramatically with the increasing temperature, when it is higher than 400 °C. |
