轧制-拉拔-退火冷却协同调控下Ti-3Al-5Mo-4.5V钛合金组织与织构演变机制

Microstructure and Texture Evolution Mechanism of Ti-3Al-5Mo-4.5V Titanium Alloy Under the Synergistic Control of Rolling-Drawing-Annealing Cooling

摘要:

研究了Ti-3Al-5Mo-4.5V（TC16）合金棒材在轧制-拉拔-不同退火冷却（水淬（WQ）、空冷（AC）和炉冷（FC））方式下微观组织和织构的协同演变机制。结果表明：TC16钛合金棒材初始片层组织在两相区轧制和退火过程中通过动态再结晶和α相长大形成了由等轴α和β相组成的双相组织，β相和α相分别形成了<110>//Y（Y//棒材轴向）和//Y的丝织构。热拉拔虽未改变织构类型，但热拉拔变形导致内部晶粒取向梯度明显增加，进而显著减弱织构强度。退火冷速速率对α相含量调控显著，等轴α相含量由WQ的36.8vol%增至FC的74.9vol%。不同冷速下的β相和α相织构类型与拉拔态织构一致。退火加热阶段α→β相变通过Burgers取向关系（BOR）继承并强化原始β相织构；而冷却过程中β→α相变因自适应效应触发变体选择，导致α相织构强度增强。由此可见，热处理可继承并强化轧制-拉拔织构，而非重构其类型。本研究通过热加工-冷却协同调控策略，为钛合金微观组织和织构优化提供参考和指导。

Abstract:

The synergistic evolution mechanism of microstructure and texture of Ti-3Al-5Mo-4.5V (TC16) alloy bar was revealed under rolling-drawing-different annealing cooling (water quenching (WQ), air cooling (AC) and furnace cooling (FC)). The results show that the initial lamellar structure of TC16 titanium alloy bar has a dual-phase structure composed of equiaxed α and β phases through dynamic recrystallization and α phase growth during two-phase rolling and annealing. The β phase and α phase form the axial silk texture of <110>//bar and //bar, respectively. Although hot drawing does not change the texture type, the hot drawing deformation leads to a significant increase in the internal grain orientation gradient, which in turn significantly weakens the texture intensity. The annealing cooling rate has a significant effect on the content of α phase, and the content of equiaxed α phase increases from 36.8vol% (WQ) to 74.9vol% (FC). The texture types of β phase and α phase at different cooling rates are consistent with the drawn texture. The α→β phase transition in the annealing heating stage retains and strengthens the original β phase texture through the Burgers orientation relationship. During the cooling process, the β→α phase transition triggers the selection of variants due to the adaptive effect, resulting in an increase in the texture strength of the α phase. It can be seen that heat treatment can retain and strengthen the rolling-drawing texture, rather than reconstruct its type. This study provides reference and guidance for the optimization of microstructure and texture of titanium alloy through the synergistic control strategy of hot processing and cooling.