亚稳 β 钛合金因兼具优异韧性、高比强度、良好耐腐蚀性与强抗疲劳性等综合性能，成为航空航天领域大型结构件的理想选材，TB18 作为 Ti-5Al-5Mo-5V-6Cr-1Fe/Nb 系新型亚稳 β 钛合金， 其固溶处理后的 β 晶粒尺寸与亚稳相析出是调控合金力学性能的核心因素，而该合金 β 相区晶粒长大行为及相析出对硬度的作用规律尚未明确。 为明晰 TB18 合金固溶处理下的 β 晶粒长大机制，揭示其硬度调控的内在规律，研究了 TB18 钛合金在 β 相区的晶粒长大行为及其对硬度的作用规律。 结果表明，经 840~990 ℃等温热处理后，TB18 钛合金 β 晶粒的等温长大曲线符合指数关系，其 β 晶粒长大指数 n 取值范围为 0.12~0.16。 动力学因素在 β 晶粒长大过程中占据主导作用，但其影响效应随保温时间的延长逐渐减弱。 TB18 钛合金 β 相晶粒长大激活能为 49.53~56.68 kJ/mol。 该合金硬度的提升主要源于原子完全固溶所引发的晶格畸变程度增大，以及 ω 相析出行为的促进效应。

The growth behavior of β grains in a TB18 titanium alloy during heat treatment and its impact on hardness were investigated. The results indicate that when subjected to isothermal heating at 840~990 ℃,the isothermal growth curve of β grains in the TB18 titanium alloy follows an exponential relationship, with a β grain growth index (n) ranging from 0.12 to 0.16. Dynamic factors play a dominant role in β grain growth, although their influence diminishes with prolonged holding time. The activation energy for β grain growth of the TB18 titanium alloy ranges from 49.53 to 56.68 kJ/mol. The increase in the hardness of the TB18 alloy is attributed primarily to the increase in lattice distortion resulting from complete atom dissolution and the promotion of ω-phase precipitation.