钛合金厚板磁控窄间隙TIG焊接接头的组织与性能

Microstructure and Mechanical Properties of Magnetically Controlled Narrow Gap TIG Welding Joint of Titanium Alloy Thick Plate

针对影响Ti-6Al-4V合金厚板磁控窄间隙TIG焊接接头力学行为的微观组织因素展开研究。测定了100 mm厚Ti-6Al-4V接头的显微硬度分布和室温拉伸性能,采用数字图像关联技术监测拉伸过程的应变分布,通过全面的微观组织表征揭示接头组织不均匀性对力学行为的影响。结果表明:接头抗拉强度达到893 MPa,接头强度系数达到94%,伸长率仅为3.8%。热影响区组织不均匀性显著,由三种典型特征组织构成。靠近母材的热影响区发生了回复和部分再结晶,成为硬度和强度最薄弱区域,拉伸过程中首先发生屈服和颈缩。接头显著的组织不均匀性导致拉伸过程中发生严重的应变局域化现象,使得接头整体伸长率显著恶化。

The microstructure factors affecting the mechanical behavior of magnetically controlled narrow gap TIG welded joint of Ti-6Al-4V alloy thick plate were systematically studied.The microhardness distribution and tensile properties at room temperature of the 100mm thick Ti-6Al-4V joint were measured.The strain distribution during tensile process was recorded by digital image correlation technology.Through comprehensive microstructure characterization,the influence of joint microstructure heterogeneity on the mechanical behavior was revealed.The results show that the tensile strength of the joint reaches 893 MPa,the joint strength coefficient is 94%,and the elongation is only 3.8%.The microstructure of heat affected zone is composed of three characteristic structures and shows a significant microstructural heterogeneity.Recovery and partial recrystallization occurs in the heat affected zone near the base metal,which exhibits the lowest hardness and strength.Yield and necking first occur in this area during tensile process.The significant microstructural heterogeneity of the joint leads to serious strain localization during tensile process,which makes the overall elongation of the joint deteriorate significantly.