异质TC17线性摩擦焊接头焊后时效处理组织与性能

线性摩擦焊是制造航空发动机整体叶盘的关键技术. 通过光学显微镜、扫描电镜、电子式万能试验机及显微硬度仪对比分析了TC17(α + β)/TC17(β)钛合金线性摩擦焊接头焊态及不同时效温度下接头的组织与性能. 结果表明，焊态下焊合区及附近区域的微观组织为过冷β细晶，硬度最低；经焊后时效处理，析出了细小针状α相，硬度升高. 焊后时效温度为400 ℃时，焊合区及附近区域的硬度值明显提高，焊接区脆化. 焊后时效温度为630 ℃时，接头弯曲角度最高，但强度降低. 综合焊接接头的硬度、弯曲与拉伸性能优化出的焊后时效温度为550 ℃. 接头弯曲角度和抗拉强度分别达到母材的36%和95%. TC17(α + β)侧热力影响区( thermal-mechanical affected zone，TMAZ)受力后微观塑性变形更均匀，其强塑性能均优于TC17(β)侧TMAZ. 接头的弱化区对应于TC17(β)侧TMAZ硬度变化梯度及组织梯度最大的区域. 相比母材，接头的塑性损失比强度损失要大得多.

Microstructure and properties of the linear friction welded joints between the different quality TC17 with post-weld aging treatments

Linear friction welding has been a key technology for manufacturing aero-engine blisks. The microstructure and properties of linear friction welded (LFW) joints of TC17 (α + β) and TC17(β) titanium alloy and post weld aging treatment (PWAT) joints at different temperature are compared by testing of optical microscope, scanning electron microscope, universal testing machine and microhardness tester. The results show that the microstructure of the weld and the surrounding area in the welded state is supercooled β-fine grained, with the lowest hardness. After post-weld aging treatment, fine needle-like α-phase is precipitated, and the hardness increases. The hardness values of the welding area and the surrounding area are obviously increased when the post-weld aging temperature is 400 ℃, and the welding area is embrittled. The bending angle of the joint is the highest, but the strength decreases when the post-weld aging temperature is 630 ℃. With the considerations of both the bending and tensile properties of the welded joint, the optimal post-weld aging temperature is found to be 550 ℃. The joint’s bending angle and tensile strength could reach 36% and 95% of that of the base metal, respectively. The micro plasticity deformations of TC17(α + β) thermal and mechanical affected zone (TMAZ) are more uniform after applying force, and its strength and plastic properties are than those of the TC17(β) side TMAZ. The weakest zone of the joint is located at TC17(β) TMAZ, where the variations of the hardness and microstructure have the greatest gradient. Compared with the base metal, the plastic loss of LFW joint is much greater than the strength loss.