CAJ | 학술논문

采用压缩实验研究应变速率和变形温度对新型亚稳β钛合金Ti2448温变形行为的影响.热模拟压缩实验在Gleeble?3800热模拟机上进行,变形温度为473~673 K,应变速率为0.001~10 s?1,变形程度为45%.结果表明:在高、低应变速率下合金呈现不同的变形特性.低应变速率(0.001~0.1 s?1)下,流动曲线呈现明显的应变硬化特性;在10 s?1的高应变速率下,流动应力在达到饱和后,因温升效应而下降;在673 K变形温度下流动应力因材料内部相变而具有显著的应变速率负敏感性.基于分段外推饱和模型和改进的Voce 模型分别构建Ti2448合金在温变形高、低应变速率下的流动应力模型;该模型得到的预测曲线(应力—应变曲线)和实验曲线吻合较好,能够有效预测Ti2448合金在温变形过程中的流动应力,其中,改进的Voce模型能同时较好地描述饱和型和非饱和型应变硬化特性.
채용압축실험연구응변속솔화변형온도대신형아은β태합금Ti2448온변형행위적영향.열모의압축실험재Gleeble?3800열모의궤상진행,변형온도위473~673 K,응변속솔위0.001~10 s?1,변형정도위45%.결과표명:재고、저응변속솔하합금정현불동적변형특성.저응변속솔(0.001~0.1 s?1)하,류동곡선정현명현적응변경화특성;재10 s?1적고응변속솔하,류동응력재체도포화후,인온승효응이하강;재673 K변형온도하류동응력인재료내부상변이구유현저적응변속솔부민감성.기우분단외추포화모형화개진적Voce 모형분별구건Ti2448합금재온변형고、저응변속솔하적류동응력모형;해모형득도적예측곡선(응력—응변곡선)화실험곡선문합교호,능구유효예측Ti2448합금재온변형과정중적류동응력,기중,개진적Voce모형능동시교호지묘술포화형화비포화형응변경화특성.
The effects of strain rate and deformation temperature on warm deformation behavior of a new kind of metastableβtitanium alloy Ti2448 were investigated by using compression tests. The experiments were carried out on a Gleeble?3800 thermo-mechanical simulator at deformation temperatures of 473?673 K, strain rates of 0.001?10 s?1, and height direction reduction of 45%. The results show that there are different deformation behaviors at high and low strain rates. At low strain rates (0.001?0.1 s?1), there are obvious work hardening behaviors in flow stress curves. At the high strain rate of 10 s?1, the alloy presents obvious hardening firstly, then saturated state and further softening caused by temperature rise finally. At 673 K, the alloy significantly exhibits the stain rate negative sensitivity because of the phase change. Based on the model in which the whole stress—strain curve is divided into the strain hardening part and the saturated state part and the modified Voce model, constitutive models were developed to describe the flow behaviors of Ti2448 alloy at high and low strain rates, respectively. The stress—strain curves predicted by the developed model well fit with the experimental results, which confirms that the developed model can predict the flow stress of Ti2448 alloy validly and the modified Voce model can describe the strain hardening behavior of both the saturated state and the unsaturated state.