热处理对Ti-38644钛合金棒材组织和性能的影响

对Ti-38644钛合金?68 mm棒材进行了不同温度、保温时间和冷却方式的热处理试验,研究了不同热处理制度对合金棒材显微组织和力学性能的影响。结果表明,随着固溶温度的升高,析出α相含量增大,强度明显下降,塑性提高;随着时效温度的升高,析出α相粗化,强度降低,伸长率随之升高,强化效果降低;随着时效保温时间的延长,析出α相进一步增加,强度呈先增加后降低的趋势,塑性变化与之相反;固溶冷却方式对合金组织性能的影响也很明显,随着冷却速率的加快,获得的β晶粒比较细小,时效后的强度随之明显增高,同时伸长率下降也很明显。为了获得良好的强塑性匹配,最佳的固溶时效热处理工艺为810 ℃×1 h(油冷)+510 ℃×8 h(空冷)。

Effect of heat treatment on microstructure and properties of Ti-38644 titanium alloy bar

Heat treatment experiments on the Ti-38644 titanium alloy with ?68 mm diameter bars were implemented at different temperatures, holding time and cooling methods. Effect of different heat treatment processes on the microstructure and mechanical properties of the alloy bars were studied. The results show that the content of the precipitated α phase increases with the solid solution temperature increase. With the increase of aging temperature, the precipitated α phase tends coarser, which result in the strength decrease, and the elongation increase. The strengthening effect is slackened. As the aging holding time extended, the precipitated α phase increase. The strength appeares a tendency to increase firstly and then decrease, and the plasticity changes in contrast. The effect of the solid solution cooling method on the alloy microstructure properties are notable. Due to the accelerates of the cooling rate, the β grains obtained is relatively small, and therefore, accounted for the strength raise up and the elongation decrease sharply. In conclusion, a better matching of strength and plasticity can be obtained in solution and aging heat treatment process (810 ℃×1 h, oil cooling+510 ℃×8 h, air cooling).