双重退火工艺对TC21钛合金力学性能和断口形貌的影响

Effect of double annealing process on mechanical properties and fracture morphology of TC21 titanium alloy

利用光学金相、扫描电镜以及拉伸、冲击、断裂韧性试验等手段研究了不同双重退火工艺对TC21钛合金显微组织和力学性能的影响。结果表明:第一次退火温度一定时,随着第二次退火温度的上升,试样中块状α相更易于形成;第二次退火温度一定时,随着第一次退火温度的上升,试样中形成大块α相的概率变小;TC21钛合金的断面收缩率对不同双重退火工艺最为敏感;900℃×2 h+500℃×4 h双重退火工艺下制备的试样具有弯折的粗大条状α相及最大的冲击吸收能量;950℃×2 h+590℃×4 h双重退火工艺下制备的试样能在裂纹扩展中吸收最多的能量,具有最高的断裂韧性。

The effect of double annealing on the microstructure and mechanical properties of TC21 titanium alloy was studied by means of OM,SEM,tensile test,impact test,and fracture toughness test. The results show that when the first annealing temperature keeps constant,the bulkα phase is easier to form with the increase of the second annealing temperature. When the second annealing temperature keeps constant,the probability of forming bulk α phase decreases with the increase of the first annealing temperature. The reduction of area of the TC21 alloy is the most sensitive to different double annealing processes. The specimens fabricated under double annealing process of 900 ℃ × 2 h + 500 ℃ × 4 h have bent large stripe α phase and have the maximum impact absorbed. The specimens fabricated under double annealing process of 950 ℃ ×2 h + 590 ℃ × 4 h can absorb the most energy during crack propagation and have the highest fracture toughness.