关键词: 切削加工, 流变行为, 本构方程, 置氢, 钛合金

Abstract: Static and dynamic compression experiments of a hydrogenated titanium alloy TC4 (Ti-6Al-4V) are carried out by means of a material testing machine and a split Hopkinson pressure bar (SHPB). Stress-strain curves are obtained over the strain rates range from 0.001 s^-1 to 15 000 s^-1 and temperatures from 293 K to 973 K. The sensitivities of the plastic flow stress to strain rate and temperature are analyzed. The experimental results indicate that all hydrogenated titanium alloy TC4 specimens exhibit a distinct heat softening effect, but that the strain rate hardening effect is comparatively weak. In addition, the strain rate hardening effect decreases as the temperature increases. The flow stress increases at first and then decreases gradually with the increase of the hydrogen content. Adding 0.3% of hydrogen in TC4 allows a maximum reduction of 25% in flow stress. The change of experimental cutting force and cutting temperature is analyzed with the flow stress at elevated temperatures in terms of the relevant cutting theory. Finally, the corresponding Johnson-Cook constitutive relation is derived, and the prediction results based on the corresponding model agree well with the experimental data.

Key words: cutting machining, flow behavior, constitutive equation, hydrogenation, titanium alloys