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利用分离式霍普金森压杆对扁平帽型试样进行加载,结合高速红外测温技术与“冻结”试样的金相微观观察,分析了TA2钛合金受迫剪切过程的力学响应及绝热剪切温度演化特性,探讨绝热剪切失稳起始温度及条件.实验结果显示:绝热剪切带起始时刻温度约为470K,明显低于再结晶温度.在此温度下,热软化还不足以导致材料应力-应变曲线软化,因此,热软化可能不是绝热剪切带起始的控制因素,相反一旦绝热剪切带形成,带内应变高度局域化导致温度发生陡然上升.若以此温度作为绝热剪切起始条件,则随平均变形速度增大,试样绝热剪切起始及破坏位移减小.
The flat hat sample was loaded by the split Hopkinson pressure bar, and the mechanical response of the “frozen” sample was analyzed by the combination of high speed infrared temperature measurement technology and the microstructure of the “frozen” sample. And the adiabatic shear temperature evolution characteristics were discussed.The onset temperature and conditions of adiabatic shear instability were discussed.The experimental results show that the initial temperature of the adiabatic shear band is about 470K which is obviously lower than the recrystallization temperature.At this temperature, Is not enough to cause material stress-strain curve to soften, so thermal softening may not be the controlling factor for the onset of adiabatic shear band, whereas on the contrary once the adiabatic shear band is formed, the in-band strain height localization leads to a sharp rise in temperature. As the starting condition of adiabatic shear, the temperature increases with the average deformation rate, and the adiabatic shear initiation and destructive displacement of the specimen decrease.