增材制造钛合金凝固晶粒调控研究进展

钛合金由于比强度高、耐腐蚀好、高温性能好等优异的性能而广泛应用于航空航天、船舶、核电等领域。增材制造技术为大型整体关键钛合金构件的短周期、低成本制造提供了变革性途径，但增材制造产生的粗大柱状晶组织导致了构件的各向异性，限制了合金性能的充分发挥。进行晶粒调控以消除各向异性、提高力学性能成为近些年的研究热点。本文简述了增材制造钛合金构件典型晶粒形貌及形成机制，阐述了国内外在增材制造钛合金晶粒调控方面的研究进展，包括工艺参数优化、微合金化改性与新合金成分设计、外加能量场、后续热处理、新型增材制造工艺和多种方法复合等，总结了各类方法的调控机理和调控效果，对增材制造钛合金凝固晶粒调控的未来发展提出了思考与展望。

Advances in obtaining refined equiaxed grains for additively manufactured titanium alloys

Titanium alloys are prevalently applied in aerospace, ship, and medical fields due to their excellent properties such as high special strength, corrosion resistance, and biocompatibility. Additive manufacturing technology provides a revolutionary way for processing the integrate and light-weight parts with short cycles. However, the coarse columnar grains produced in the forming process lead to the anisotropy of the components, which limits the full play of the properties for the alloys. To control the size and morphology of the grains is the hotspot in recent years. This study briefly describes the feature and formation mechanism of typical grain microstructures in general additive manufacturing methods, expounds grain-control methods in parameters optimization, novel processing methods, micro-alloying/new alloy composition design, subsequent heat treatment, external field assistance, and the combination of these methods. The grain regulation mechanisms are summarized and the control effects are evaluated. Most of the control methods can obtain full-equiaxed grains and weaken the anisotropy of mechanical properties in the room-temperature tensile test. Subsequent treatments and mechanical properties evaluation of the obtained equiaxed microstructure alloys are expected to achieve the target properties and engineering application through further research.