TC4钛合金真空电子束焊焊接接头组织性能与腐蚀行为研究

Study on microstructure and corrosion behavior of TC4 titanium alloy vacuum electron beam welded joints

真空电子束焊具有能量集中度高、热影响区小等优点,在钛合金焊接领域被广泛应用。本文研究了TC4钛合金薄板真空电子束焊对接组织性能以及在不同腐蚀介质中的腐蚀行为及特征。研究结果表明:接头母材区组织是等轴α相和间隙β相的机械混合,焊缝区组织为针状马氏体(α'相),热影响区由原始α相、β相加α'相构成;接头显微硬度明显高于母材且随着与母材距离的增加,硬度逐渐增加;同时焊缝区网篮组织的形成使接头拉伸强度和断面收缩率更高,塑性更好。在3.5%NaCl溶液中,母材的腐蚀倾向大于焊缝,而在10%HCl溶液中则相反,焊缝成为薄弱环节;同时,焊接接头在10%HCl溶液中自腐蚀电流显著高于在3.5%NaCl溶液中,说明介质对接头的电化学腐蚀性能影响显著。

Vacuum electron beam welding has the advantages of high energy concentration and small heat affected zone,which is widely used in the field of titanium alloy welding.In this paper,the microstructure and properties of TC4 titanium alloy sheet by vacuum electron beam welding butt-joints and the corrosion behavior and characteristics in different corrosion media are studied.The results show that the microstructure of Welded joint base material area is a mechanical mixture ofα-phase andβ-phase.Weld zone microstructure is acicular Martensite(α’phase)and the HAZ is the originalα-phase andβ-phase fine needle-like Martensite structure.Joint microhardness gradually decreases from weld zone to base metal and strength and plasticity are higher beause of the formation of basket structure.In the 3.5%NaCl solution,the corrosion tendency of the base metal is greater than that of the weld,while in the 10%HCl solution,the weld becomes a weak link;at the same time,the self-corrosion current of the welded joint in the 10%HCl solution is significantly higher than that in the 3.5%NaCl solution,indicating that the medium has a significant impact on the electrochemical corrosion performance of the joint.