Ti-22Al-27Nb合金线性摩擦焊接头组织与显微硬度分析

对Ti-22Al-27Nb合金进行了线性摩擦焊及热处理试验，并对热处理前后焊接接头的微观组织和显微硬度进行测量分析. 结果表明，利用线性摩擦焊方法焊接Ti-22Al-27Nb合金得到的接头无焊接缺陷. 焊态下，焊缝区形成了B2单相区组织. 热力影响区为B2 + O + α₂相三相区，出现等轴α₂相，针状O相几乎消失. 热处理后在焊缝区析出板条状O相和针状O相，热力影响区为O相均匀分布的两相区. 母材处的显微硬度值最低约为300 HV，随着向焊缝靠近，显微硬度值逐渐增加，焊缝中心达到最大值354 HV. 热处理后，由于板条O相和针状O相的沉淀析出，使焊缝中心显微硬度急剧增加.

Study on microstructure and microhardness of linear friction welded joints of Ti-22Al-27Nb alloy

In this paper, the Ti-22Al-27Nb based alloy was welded by linear friction welding (LFW), and then subjected to post-weld heat treatment. The microstructure and the microhardness of the linear friction welded joints were investigated. The results showed that the sound joints free of defects can be obtained by using LFW method. As welded condition, the weld zone is mainly composed of metastable B2 phase. In thermo-mechanically affected zone, equiaxial α₂ occurred in this zone and the acicular O phase nearly disappeared. After heat treatment, the lath O phase and acicular O phase precipitated at weld zone, the thermo-mechanically affected zone is a two-phase region with uniform distribution of O phase. The microhardness of base material is about 300 HV, the microhardness increases with approaching to weld center, which maximum microhardness is 354 HV. After heat treatment, the microhardness of the weld center increased sharply due to precipitation of lath O and acicular O phase.