Title: Effect of Aging Treatment on Microstructure and Mechanical Properties of Linear Friction Welded Ti-22Al-25Nb Alloy
文章编号: 1009-9964(2020)-37-4-001
作者: 高伟1，陈曦1,2,谢发勤2, 李文亚2, 郝建民1,郝婧渌1
(1.长安大学, 陕西西安710064)(2.西北工业大学,陕西西安710072)
Author(s): Gao Wei1,Chen Xi1,2, Xie Faqin2,Li Wenya2,Hao Jianmin1, Hao Jinglu1
(1. Chang’an University, Xi’an 710064, China）（2.Northwestern Polytechnical University, Xi’an 710072, China)
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摘要: 对Ti-22Al-25Nb合金线性摩擦焊接头进行840 ℃×2 h的时效处理，研究了焊接头的组织和力学性能。结果表明，焊接头主要分为3个区域，分别是焊缝区、热力影响区和母材区。焊缝区组织以B2相为主，α2相和O相的数量相对较少。热力影响区仅有少量的α2相和O相转变为B2相，且α2相形态变化不大。EBSD分析结果表明，母材的晶体学取向无法遗传到最终的焊缝组织中。经过840 ℃时效处理后，焊缝区发生了动态再结晶并析出了O相。在热力影响区，α2相的分解并不充分，可以观察到rim-O相围绕α2相析出。母材区O相有所长大，而α2相的形态无明显变化。时效处理之后细晶强化与O相的析出强化作用显著提高了焊接头的力学性能。
Abstract: The microstructure and mechanical properties of linear friction welded Ti-22Al-25Nb alloy were studied after aging at 840 ℃ for 2 h. The results show that the welded joint can be divided into three parts: weld zone, TMAZ and base metal. The microstructure of weld zone is dominated by B2 phase, while the volume fraction of α2 and O phase is relatively small. Only a small amount of α2 and O phase transformed into B2 phase in TMAZ, and the morphology of α2 phase changes little. The EBSD results show that the crystallographic orientation in base metal cannot be inherited into the final weld structure. After aging at 840 ℃, the recrystallization and the precipitation of O phase can be observed in weld zone. The decomposition of α2 phase is insufficient in TMAZ, while the rim-O phase precipitated around α2 phase can be observed. In base metal, the O phase has grown up, while the α2 phase has no obvious change. After the heat treatment, the strengthening of the O phase precipitation and the refined grains significantly increased the mechanical properties of the joint.
关键词: Ti-22Al-25Nb合金；线性摩擦焊；时效处理
Keywords: Ti-22Al-25Nb alloy; linear friction welding; aging treatment
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