Abstract A novel composited process including solution treatment-hot gas forming and stress relaxation aging is proposed in this paper to form titanium alloys component with high precision and improved strength simultaneously. Firstly, solution and aging treatments were carried out to study the effects of processing parameters on microstructure and properties. Secondly, uniaxial tensile tests at solution temperature were used to study the hot deformation. Thirdly, stress relaxation aging tests were performed to investigate the relation between stress relaxation and aging; Finally, sophisticated forming tools integrating air cooling channels were designed to validate this novel process by forming a TA15 alloy nozzle. Results show that Nano-scaled secondary α formed in the β matrix after the heat treatment at 950 °C/30 min/WQ + 600 °C/120 min/AC, which increased the ultimate strength of TA15 alloy by 11.8 %. Hot deformation at solution temperature of 950 °C could reduce the elastic strain by 50 % compared with that at 600 °C. The stress relaxation aging could not only further improve the strength of the sample but also increase the relaxation rate, which may result from more nucleation sites for the secondary α provided by the dislocations generated during the loading. A TA15 alloy nozzle was successfully formed by this novel composited process, and the final formed part obtained a diameter deviation less than 0.25 mm and post-form hardness improved by 8.6 %.

中文翻译：

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钛合金固溶处理-热气成型与应力松弛时效复合新工艺

摘要 本文提出了一种包括固溶处理-热气成型和应力松弛时效的复合工艺，以同时形成高精度和提高强度的钛合金部件。首先，进行固溶和时效处理，研究加工参数对组织和性能的影响。其次，采用固溶温度下的单轴拉伸试验来研究热变形。第三，进行应力松弛老化试验，研究应力松弛与老化的关系；最后，设计了集成空气冷却通道的精密成型工具，通过形成 TA15 合金喷嘴来验证这一新工艺。结果表明，在 950 °C/30 min/WQ + 600 °C/120 min/AC 热处理后，在 β 基体中形成了纳米级次生 α，TA15合金的极限强度提高了11.8%。与 600°C 相比，950°C 固溶温度下的热变形可使弹性应变降低 50%。应力松弛时效不仅可以进一步提高样品的强度，还可以提高松弛速率，这可能是由于加载过程中产生的位错为二次α提供了更多的形核位点。采用这种新型复合工艺成功成型了TA15合金喷嘴，最终成型件的直径偏差小于0.25 mm，成型后硬度提高了8.6%。应力松弛时效不仅可以进一步提高样品的强度，还可以提高松弛速率，这可能是由于加载过程中产生的位错为二次α提供了更多的形核位点。采用这种新型复合工艺成功成型了TA15合金喷嘴，最终成型件的直径偏差小于0.25 mm，成型后硬度提高了8.6%。应力松弛时效不仅可以进一步提高样品的强度，还可以提高松弛速率，这可能是由于加载过程中产生的位错为二次α提供了更多的形核位点。采用这种新型复合工艺成功成型了TA15合金喷嘴，最终成型件的直径偏差小于0.25 mm，成型后硬度提高了8.6%。