热处理对Ti1300高强钛合金电子束焊接组织和力学性能的影响

Effect of Heat Treatments on Microstructure and Mechanical Property of Electron Beam Weldment of Ti1300 Alloy

摘要:

对不同原始状态的Ti1300合金电子束焊接样品进行不同的热处理,研究了焊前热处理和焊后热处理工艺对合金焊接样品的组织和力学性能影响。结果表明,焊接前不同热处理对合金焊缝组织和性能影响不大,在焊缝无热处理情况下,焊缝主要由较大尺寸的柱状β晶和亚晶构成,形成的α相极少,并主要分布在稳定晶粒的晶界处,这种组织使得焊缝区的强度和塑性明显低于基体。焊接后无论采取哪种热处理工艺,都无法改变合金焊缝区β晶粒的形态和尺寸,亚晶依然存在。热处理可以调节焊缝区α相的含量、尺寸和形态,但析出的α相的分布总体趋向于在稳定晶界处形成。焊缝区的性能依赖于析出α相的尺寸和数量,当单独在较低温度退火或时效时,焊缝区α相强化效果明显,焊缝强度大于基体,断裂发生在基体。

Abstract:

The microstructures and mechanical properties of electron beam weldment Ti1300 alloy after or before different heat treatment were investigated. The results indicated that the various heat treatments before welded treatment cause little effect on microstructures and mechanical properties for different samples. The fusion zone microstructure of non heat treatment (NHT) specimen after welded treatment is mainly composed of columnar β grain and β subgrain with big size, and there is small amount of α phase distributing at high-angle boundary in the fusion zone. This microstructure shows low strength and elongation in comparison to matrix. For the welded specimens after various heat treatments, the morphology and size of columnar β grain or β subgrain, and the distribution of α phase during heat treatment can not be changed. However, the morphology, size and quantity of α phase can be adjusted for different heat treatments, and which determined the mechanical properties of weld joint zone. For the welded samples after annealing or ageing treatment, α phase shows high strengthening effect in comparison to matrix and which result in the failure occurrence in matrix.