Research On Welding Material And Process For Fusion Weld Butt Joints Of Titanium-steel Composite Plate

With the progressly growing of energy consume demand,it has become inevitable for long distance transportation of oil and gas,but it attracted the attention of people on the corrosion resistance of oil and gas pipeline.because of the frequent occurence of oil and gas leakage and pipeline explosion accidents.Corrosion cracking is the main reason about cause the oil and gas pipelines leak.In order to improve the pipeline corrosion resistance,people have tried to use pure stainless steel and titanium alloy to manufacture oil and gas pipelines,but the high cost makes people have to find another way.Titanium-steel composite pipe integrates the corrosion resistance of titanium and high strength and toughness of steel and solves this problem very well.Because of the large difference of physical and chemical characteristics for titanium and steel,it was too difficult to fusion weld joint.In the paper,the research was TA1/X65 layered-composite plate,based on the particularity and suitability of melting welding non-uniform temperature field and the layers of weld metal solidification of titanium-steel composite,it analyzes the differences of strength and toughness and transition layer interface adapter and other issues of titanium-steel welding.Welding materials of TA1/X65 layered-composite plate in cach layer had been respectly designed according to the strong and thinning properies of weld scam in welding process and the phase formation mechanism.At the same time,combining with the working process had been developed.By the overlaying welding and the macro and micro weld analysis,TA1 solid core wire as the welding materials for titanium layer,Cu base flux-cored wire as the welding material for transition layer and ER50-6 as welding material for steel layer can be well metallurgical connection for titanium and steel,but the weld microstructure was relatively bulky,in the weld,a small amount of Micro-crack was found and the bending perfornance was poor.Through docking testing and analysis of weld microstructure and peroperities found that,the metal intermetallic compound of Ti and Fe?C was the main causes of poor mechanical properties of weld,the metal intermetallic compound has high hardness and brittleness.Combining the analysis results,and the optimization of parent metal structure,titanium-copper-steel composite panels have been prodected by explosive production,the element diffusion problems in titanium and steel at the grass-roots level have been solved fundamentally,And through the optimization of composite plate welding process,the metallurgical bonding of titanium-steel composite panels have been achieved finally.According to the scanning electron microscope,energy spectrum and XRD analysis,the intermetallic compound of Ti,Fe and C elements was not detected in the weld,the mechanical properties of welded joint have been improved.