测试了TG6钛合金盘锻件STA状态+再经600℃,100 h试样热暴露在不同温度下的拉伸性能.TG6钛合金随着温度升高,抗拉强度下降,塑性提高.在室温下,与STA状态试样相比,经热暴露后的试样拉伸塑性显著降低,而当测试温度在150℃以上时,试样热暴露后的拉伸塑性显著提高,亦即热稳定性得到很大程度的恢复.引起TG6钛合金热稳定性下降的主要因素是有序α2相的共格析出和表面氧化.在150℃以上的高温条件下,热稳定性的恢复归因于位错滑移模式的变化,随着温度的升高,由位错剪切α2相的集中平面滑移逐渐向位错交滑移转变,促进位错更为均匀的滑移,从而提高塑性,表现在断口上为宏观的平面形向波浪形断裂特征的转变.
The tensile properties of TG6 titanium alloy forging disc as solution and aging treatment (STA) state and STA plus 600 °C, 100 h exposed state were tested at various temperatures. The results show that the tensile strength decreases while the ductility increases with the test temperature increasing. Compared with as STA state, the room temperature tensile plasticity of the specimen subjected to a long-term thermal exposure decreases remarkably. However, once the temperature rises over 150 °C, the tensile ductility increases rapidly, namely, the thermal stability gets a recovery to a great extent. The loss of thermal stability of TG6 titanium alloy may be mainly attributed to the coherent precipitation of α2 phase and surface oxidation. When the temperature is above 150 °C, the resumption of the thermal stability would come from the change of dislocation slip mode. Upon temperature rising,the slip mode of the dislocation changes fi'om concentrated slip mode by curing the coherent α2 particles to cross slip mode, which will promote a more homogeneous plastic deformation and result in the improvement of tensile ductility, showing the characteristic of the macro-transferring from a planar slip to a wave slip on the fracture surface.
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