TC21钛合金α片层静态球化动力学

Static spheroidization kinetics ofαlamellar of TC21 titanium alloy

对TC21钛合金进行了1~3个锻造周期(对应的应变分别为1.60、2.71和3.82)的锻造。对锻造试样进行了温度为860~920℃,时间为0.5~4 h的后续球化热处理实验,利用定量金相法、扫描电子显微镜和电子背向散射衍射技术研究了不同应变、热处理温度和热处理时间等工艺参数对TC21钛合金α片层静态球化的影响规律,揭示了其静态球化机理,并建立了TC21钛合金静态球化动力学方程。结果表明,静态球化体积分数随热处理时间的增加呈现抛物线式增长;应变越大,静态球化体积分数越大;应变较小时静态球化对热处理温度的变化更敏感。其静态球化机理主要为:β相楔入α/α界面、奥斯瓦尔德熟化和连续静态再结晶共同作用。

TC21 titanium alloy was forged for 1-3 forging cycles(corresponding true strains were 1.60,2.71 and 3.82,respectively).The subsequent spheroidization heat treatment experiments were conducted on forged samples at 860-920℃for 0.5-4 h.The effect laws of different process parameters,such as strain,heat treatment temperature and heat treatment time,on the static spheroidization of TC21 titanium alloyαlamellar were studied by quantitative metallographic method,scanning electron microscopy(SEM)and electron back-scattered diffraction(EBSD)techniques,the static spheroidization mechanism was revealed,and the kinetics equation of static spheroidization of TC21 titanium alloy was established.The results show that the static spheroidization volume fraction presents parabolic increase with the increase of heat treatment time.The larger the strain is,the larger the static spheroidization volume fraction is.The static spheroidization with smaller strain is more sensitive to the change of heat treatment temperature.The main static spheroidization mechanism is the combination ofβphase wedgingα/αinterface,Oswald ripening and continuous static recrystallization(CSRX).