固溶时效对TC21钛合金准β锻后组织性能的影响

Effect of solution aging treatment on the microstructure properties of TC21 titanium alloy after quasi-beta forging

摘要:

对TC21钛合金进行准β锻造，再进行固溶时效热处理实验，研究了不同固溶时效热处理制度对合金的微观组织和力学性能的影响。结果表明，TC21钛合金通过准β锻造后，再经固溶时效热处理工艺处理后，合金的微观组织呈现典型的网篮组织。随着固溶温度的上升，片状α相含量和长度显著降低，同时合金强度增加，而塑性变化呈相反趋势。随着时效温度的上升，对片状α相的影响略小，但次生α相的厚度此时显著增加，此时合金强度降低，塑性提高。断口形貌则随着固溶温度的升高，断口表面和裂纹扩展路径愈发平坦。断裂韧性值呈现下降趋势，但会随着时效温度的升高而提高。合金最大断裂韧性值可达66MPa·m1/2。考虑合金的强度、塑性和断裂韧性之间的良好匹配，经综合分析可得，TC21钛合金准β锻后最佳热处理制度为:870 ℃/2 h,AC+590 ℃/4 h,AC。

Abstract:

The quasi-β forging of TC21 titanium alloy was carried out,and then embarked on the solution aging heat treatment experiment,and the effects of different solution aging heat treatment systems on the microstructure and mechanical properties of the alloy.The results showed that after TC21 titanium alloy was forged by quasi-β and treated by solution aging heat treatment process,the microstructure of the alloy presents a typical basket-weave structure.With the increase of solution temperature,the content and length of the lamellar α phase decrease significantly,and the strength of the alloy increase,while the plasticity change showed the opposite trend.With the increase of aging temperature,the effect on the lamellar α phase was slightly smaller,but the thickness of the secondary α phase increases significantly,and the strength of the alloy decreases and the plasticity increases.The morphology of the fracture becomes flatter with the increase of the solution temperature,and the fracture surface and crack growth path become flatter.The fracture toughness value presented a downward trend,but it increased with the increase of aging temperature.The maximum fracture toughness value of the alloy can reach 66MPa·m1/2.Considering the good match between the strength,plasticity and fracture toughness of the alloy,after comprehensive analysis,it can be obtained that the best heat treatment system of TC21 titanium alloy after quasi-β fracture is:870°C/2 h,AC+590°C/4 h,AC.