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使用Gleeble-3800热模拟试验机在温度为800~1000℃、应变速率为0.01~10 s~(-1)、变形程度为70%的条件下对锻态β-CEZ钛合金进行热模拟试验。利用试验数据及Prasad判据绘制了真应力-真应变曲线和加工图,研究了该合金在α+β两相区和β单相区的高温变形行为、变形失稳现象和变形机制。结果表明:本实验条件下β-CEZ钛合金表现出动态回复和动态再结晶2种软化机制,在α+β两相区流动应力达到峰值后随应变的增大而缓慢下降,在β单相区流动应力达到峰值后发生不连续屈服现象快速下降一段后趋于稳定;功率耗散率η出现极大值的区域在α+β两相区为850~890℃/0.01~0.05 s~(-1),是片层α相球化的区域;在β单相区为940~980℃/0.2~0.6 s~(-1),是动态再结晶区域;流动失稳区为800~850℃/0.1~10 s~(-1),850~900℃/0.1~5 s~(-1),900~1000℃/1~10 s~(-1),失稳现象在α+β两相区表现为绝热剪切带,在β单相区表现为不均匀变形。
The thermal simulations of forged β-CEZ titanium alloy were carried out on a Gleeble-3800 thermal simulator at a temperature of 800-1000 ℃, a strain rate of 0.01-10 s -1, and a deformation degree of 70%. The true stress-true strain curves and the processing diagrams were drawn by using the experimental data and Prasad criterion. The high-temperature deformation behavior, deformation instability and deformation mechanism of the alloy in α + β two-phase region and β single-phase region were studied. The results show that the β-CEZ titanium alloy exhibits two kinds of softening mechanism of dynamic recovery and dynamic recrystallization under the experimental conditions. When the flow stress in the α + β two-phase zone reaches the peak value, the β-CEZ titanium alloy decreases slowly with the increase of strain, When the flow stress peaked, the discontinuous yielding tended to be stable after a period of rapid decline. The region where the power dissipation rate η appeared maximum was in the range of 850 ~ 890 ℃ / 0.01 ~ 0.05 s ~ (- 1) is the α-phase lamellar α-phase spheroidized region. In the β-single phase region of 940-980 ℃ / 0.2-0.6 s -1, it is a dynamic recrystallization region. The flow instability region is 800-850 ℃ / 0.1 ~ 10 s ~ (-1), 850 ~ 900 ℃ / 0.1 ~ 5 s ~ (-1), 900 ~ 1000 ℃ / 1 ~ 10 s ~ The performance of adiabatic shear band in the single-phase β showed uneven deformation.