固溶温度对3D打印TC4钛合金显微组织和力学性能的影响

对3D打印TC4钛合金进行不同温度固溶+490 ℃时效处理,通过显微组织观察和力学性能试验对其微观组织和力学性能进行了研究。结果表明,3D打印TC4钛合金在原始沉积态时为不均匀的网篮组织,经固溶时效处理后,随着固溶温度的升高,组织中α相先以片状的形式生长于完整的原始晶界附近,再逐渐转变为粗大的板条状,强度逐渐升高而塑性有所降低,当固溶温度为920 ℃时,强度达到最大值,为1100 MPa。当固溶温度超过960 ℃时,α相逐渐被溶解,强度逐渐下降,同时塑性也表现较差。经扫描电镜观察,不同固溶温度下拉伸断口的宏观形貌均呈暗灰色,经890~960 ℃固溶+490 ℃时效处理的TC4钛合金,其微观形貌中存在的大量韧窝,可以判断出其断裂机制为韧性断裂。结合不同固溶时效处理后钛合金的显微组织及力学性能变化可以得出,经920 ℃固溶+490 ℃时效处理后的3D打印TC4钛合金具有较好的综合力学性能。

Influence of solution treatment temperature on microstructure and mechanical properties of TC4 titanium alloy prepared by 3D printing

Microstructure and mechanical properties of TC4 titanium alloy prepared by 3D printing after solution at different temperature and then aging at 490 ℃ were studied through microstructure observation and mechanical property test. The results indicate that the microstructure of the original 3D printed deposition sate is non-uniform basket-weave structure. After solution and aging treatment, with the increase of solution temperature, the α phase first grows in the form of flakes near the complete original grain boundary, and then gradually transforms into a coarse lath shape, and the strength gradually increases while the plasticity decreases, reaching the maximum value of 1100 MPa when solution temperature is 920 ℃. As the solution temperature further increases and exceeds 960 ℃, the α phase is gradually dissolved, which leads to the decrease of the strength and the plasticity. The macro morphologies of the tensile fracture under different solution temperature are all dark gray. According to a large number of dimples observed in the micro morphologies of those fracture, the tensile fracture mechanism of the TC4 titanium alloy can be judged as ductile fracture when solution treated at 890-960 ℃ and aged at 490 ℃. Combining the changes in the microstructure and mechanical properties of the TC4 titanium alloy after different solution and aging treatments, it can be concluded that the TC4 titanium alloy prepared by 3D printing has better comprehensive mechanical properties when solution treated at 920 ℃ and then aged at 490 ℃.