Study On TIG Welding Of Titanium Alloy And Stress Corrosion Cracking Of TC4 Titanium Alloy Welded Joint

With the development of the times,the development and utilization of the ocean has become the focus of the world.Titanium alloy has become the first choice material for marine equipment since its superior comprehensive performance.But There are many problems in the sheet welding of TC4 titanium alloy,such as welding deformation,large grain growth and so on,and the joint is easy to be the weak part of stress corrosion.The use of welded joints is often in the environment of cathodic hydrogen evolution,and there is danger of hydrogen embrittlement.The weldability of TB5 titanium alloy is rarely studied,which limits its extensive application.In this paper,the study is about the weldability of TIG welding between TC4 titanium alloy and TB5 titanium alloy which are used in marine equipment.The TIG welding parameters of sheet TC4 titanium alloy were optimized.The mechanical properties of welded joints were tested.The hardness of welded joints was determined,and the relationship between microstructure and mechanical properties was analyzed.At the same time,the slow tensile test of TC4 titanium alloy welded joint and slow tensile test after hydrogen charging were carried out.The stress corrosion susceptibility of titanium alloy welded joint and susceptibility of hydrogen embrittlement were studied.In this paper,mechanical properties analysis and microstructure observation of TB5 titanium alloy TIG welded joint with different welding forming method were also carried out and the weldability of TB5 titanium alloy was analyzed.After the analysis of the mechanical properties and microstructure of the TC4 titanium alloy welded joint with 2mm thickness,it was found that the welding joint had the best performance when the welding current was 80 A and the welding speed was 13m/h.The fracture position of the joint was at the base of the base material and the coarse grain problem was solved to some extent.Through the slow tensile test of welded joints,the experimental results showed that the stress corrosion cracking susceptibility of TC4 titanium alloy welded joints was increased with the increase of slow tensile rate.But general showed strong resistance to stress corrosion.At the same time,the effect of hydrogen filling on the susceptibility of TC4 titanium alloy welded joint hydrogen embrittlement was little.For TB5 titanium alloy,the mechanical properties of the welded joint were great,which were similar to base metal.After welding,the microstructure of double-sided welding had secondary phase,which improved the toughness of welded joint,and generally showed good weldability.