Ti6242合金微观组织差异及其演变对拉伸和疲劳性能影响

Effects of Microstructure Difference and Evolution on Tensile and Fatigue Properties of Ti6242 Alloy

典型近α型钛合金Ti6242合金制备盘锻件的综合力学性能与其棒材原始微观组织特征密切相关。本研究选取具有明显微观组织特征差别的3种Ti6242钛合金棒材为研究对象,定量化评估不同Ti6242钛合金棒材锻造态、固溶态和固溶+时效态的微观组织差别和演变规律,并讨论棒材微观组织差别和演变对综合力学性能的影响。研究结果显示具有明显差别的不同棒材微观组织在经历相同的固溶和时效处理后,其初生α相体积分数差别趋于相近,而初生α相的尺寸分布和形状分布等微观组织特征仍保留差别;力学性能结果显示室温拉伸力学性能趋于近似,而低周疲劳和保载疲劳力学性能对微观组织特征较为敏感。对比不同特征组织和力学性能分析结果,具有细小非等轴状且没有明显取向集中分布初生α相的棒材原始组织有助于获得更好的疲劳性能。

The mechanical properties of the near-alpha titanium alloys Ti6242 alloy disc forgings usually have close relationship with the original microstructure of bars.In this study,three kinds of Ti6242 alloy bars with different original microstructure were selected to quantitatively analyze the difference and evolution of different microstructure characteristics,including the forged state,the solid solution state and the solid solution and aging state.The effects of the microstructure difference and evolution on the mechanical properties were also compared.The results showed that the differences of primaryαphase volume fraction reduced after similar solid solution and aging treatment process,while the sectional area distribution and shape distribution of primaryαphase still retained some differences.Room temperature tensile mechanical properties showed no significant difference,while the low fatigue property and dwell fatigue property exhibited significant difference.According to the microstructure difference analysis and mechanical property results,the original microstructure of bar with fine,non-equiaxed and no obvious orientation primary alpha phase contributed to good fatigue properties.