TB18钛合金固溶时效工艺正交优化及韧性调控机制

Orthogonal Optimization of Solution Treatment and Aging Process for TB18 Titanium Alloy and Toughness Regula-tion Mechanism

摘要:

为探究固溶时效工艺参数对TB18钛合金微观组织与力学性能的影响规律，基于混合正交试验因素水平试验设计开展工艺优化研究。结果表明，结合极差分析确定工艺参数影响显著性顺序为：固溶冷却方式>固溶温度>时效时间>时效温度>固溶时间。综合强塑性匹配与工程应用需求，选定固溶时间1 h、固溶冷却方式空冷（AC）、时效温度525 ℃、时效时间4 h为基准参数，进一步研究790~870 ℃固溶温度区间对合金冲击韧性及微观断口特征的影响。结果显示，剪切唇和纤维区面积越大，放射区面积越小，合金韧性越优；随固溶温度升高，断口二次裂纹长度增加，韧窝数量增加，韧性增强。基于强塑韧性协同优化，确定TB18合金最优的热处理工艺为870 ℃/1 h, AC+525 ℃/4 h, AC。

Abstract:

To investigate the effect of solution treatment and aging process parameters on the microstructure and mechanical properties of TB18 titanium alloy, process optimization research was conducted based on the mixed-level orthogonal experiment design of factor levels. Results show that through range analysis, the significance order of process parameters is determined as follows: solution cooling method>solution temperature>aging time>aging temperature>solution time. Considering the strength-ductility matching and engineering application requirements, the benchmark parameters are selected as solution time of 1 h, solution cooling method of air cooling (AC), aging temperature of 525 °C, and aging time of 4 h. Furthermore, the effects of solution temperature in the range of 790–870 °C on the impact toughness and micro-fracture characteristics of the alloy were studied. The results reveal that the larger the area of shear lip and fibrous zone, and the smaller the area of radiation zone, the better the toughness of the alloy. With the increase in solution temperature, the length of secondary cracks on the fracture surface increases, the number of dimples increases, and the toughness is enhanced. Based on the collaborative optimization of strength and toughness, the optimal heat treatment process for TB18 alloy is determined as 870 °C/1 h, AC+525 °C/4 h, AC.