固溶冷却方式对TB15钛合金组织和力学性能的影响

采用扫描电镜观察、拉伸和断裂韧性测试研究了不同固溶冷却方式下TB15钛合金经900 ℃×2 h固溶+530 ℃×8 h时效后的力学性能、断口形貌和显微组织。结果表明,固溶冷却方式对TB15钛合金强度和塑性的影响较大,对断裂韧性的影响较小。固溶后回充0.1 MPa氩气真空气冷时,合金的综合力学性能最好,抗拉强度为1391 MPa,伸长率为7.0%,断面收缩率为13.6%,断裂韧度为70.3 MPa·m^1/2。随着固溶冷却速率的增加,TB15钛合金的断裂韧度逐渐减小,但变化幅度不大。不同固溶冷却方式下,TB15钛合金经固溶时效后的次生α相数量、厚度及片层间距有所不同。与空冷相比,回充0.1 MPa氩气真空气冷的片层状次生α相数量增多,厚度略有增加,片层间距有所增大。

Effect of solution cooling method on microstructure and mechanical properties of TB15 titanium alloy

Mechanical properties, fracture morphology and microstructure of TB15 titanium alloy after solution treatment at 900 ℃ for 2 h with different cooling methods and aging at 530 ℃ for 8 h were studied by means of scanning electron microscopy, tensile and fracture toughness tests. The results show that cooling method of solution treatment significantly affects the strength and ductility of TB15 titanium alloy, but the effect on fracture toughness is not obvious. When using 0.1 MPa argon vacuum quenching, the comprehensive mechanical properties of the TB15 titanium alloy after solution and aging is the best, as the tensile strength is 1391 MPa, the elongation is 7.0%, the percentage reduction of area is 13.6%, and the fracture toughness is 70.3 MPa·m^1/2. With the increase of solution cooling rate, the fracture toughness of the TB15 titanium alloy gradually decreases, but its varied range is not large. Under different solution cooling methods, the number, thickness and lamellar spacing of secondary α phase in TB15 titanium alloy after solution and aging are different. Compared with air cooling, the number and thickness of the lamellar secondary α phase increase when using 0.1 MPa argon vacuum quenching.