初生α相含量对近α钛合金TG6拉伸性能和热稳定性的影响

Effect of Primary α Phase Volume Fraction on Tensile Property and Thermal Stability of Near-Alpha TG6 Titanium Alloy

采用力学性能测试和断口分析等方法研究了初生α含量对TG6高温钛合金双态组织拉伸性能和热稳定性的影响。当双态组织中的初生α含量大约在20%-50%的范围内时,TG6钛合金的拉伸强度和塑性没有特别大的差别。但当经过600℃/100h的试样热暴露后,TG6钛合金的拉伸强度略有增加,而塑性则明显降低。塑性下降的程度与合金的初生α相含量密切相关,初生α含量越少,则热暴露后塑性下降幅度越大。导致TG6钛合金热暴露后塑性损失的主要因素有共格α2相的析出、硅化物的析出以及表面氧化。相对而言,其中共格α2相的析出是合金热暴露后塑性损失的最主要因素。

The effect of primary α phase volume fraction on the tensile property and thermal stability of the near-α TG6 Ti-alloy is investigated using mechanical properties testing and fracture analysis. The tensile strength and ductility have no obvious difference when the primary α fraction varies from 20% to 50%. While the specimens are subjected to 600℃/100h exposition in the high temperature air environment, the tensile strength increases slightly and the specimens decrease seriously. The degree of ductility degradation is strongly depended on the equiaxed primary ct fraction. Decreasing the primary α fraction may accelerate the ductility loss after thermal exposition. There are several structural and environmental factors enhance the ductility degradation for TG6 alloy, such as coherent α2 precipitation, silieide and surface oxidation, eontrastively, coherent α recipitation during the thermal exposition plays the most important role.