Ti-600合金热暴露前后室温拉伸性能及变形机制研究

研究了Ti-600合金镦制饼材600℃热暴露前后室温拉伸性能与组织的变化,并分析了其室温拉伸变形机制。研究结果表明,600℃热暴露100 h后,毛坯热暴露试样的强度较热暴露前的固溶时效试样(STA)提高了3%左右,延伸率的保持率为81.1%;试样热暴露试样的强度稍有降低,延伸率的保持率仅为55.6%。600℃热暴露100 h前后,Ti-600合金镦制饼材的组织变化不明显,热暴露后其原始β晶粒尺寸较之前的稍有长大。STA状态下晶界与板条较平直,热暴露后少数板条弯曲,并且板条较短较细小。试样热暴露试样组织内的α相与β板条比毛坯热暴露试样的粗大。经分析,Ti-600合金热暴露前后室温拉伸变形时主要的变形机制是位错穿越α束滑移以及位错柱面滑移。

Tensile Properties and Deformation Mechanism at Ambient Temperature for Ti-600 Alloy Before and After Thermal Exposure

Tensile testes were carried out at ambient temperature on Ti-600 alloy before and after being exposed at 600℃ for 100 h. Morphologies were investigated and deformation mechanism was also analyzed. The results indicate that the strength of the sample without oxidizing layers increases 3 % or so, the retention rate of elongation is 81.1% for the alloy exposed at 600 ℃ for 100 h. While for the sample with oxidizing layers, the strength decreases a little bit, the retention rate of elongation is only 55.6%. The morphologies of the alloy after being exposed at 600 ℃ for 100 h are almost the same as that of the alloy before thermal exposure. The size of primary transformed β grains becomes a little bigger after thermal exposure. The grain boundaries, α and β lathes are plain and flat, while some of which are with curve shape, short and fine a and β lathes can be found. And lathes in the samples with oxidizing layers are coarse than that in the samples without oxidizing layers. During the tensile deformation process at ambient temperature prior to and after long time high temperature thermal exposure, the main deformation mechanisms for the Ti-600 alloy are not only the slips of dislocation across the a clusters, but also prismatic slips of dislocations.