Numerical analysis of electron beam welding of different grade titanium sheets

Abstract

In the paper the numerical analysis of a titanium sheet welding process was presented. During the welding process sheets made of titanium Grade 2 and Grade 5 were joined using electron beam welding technology. The result of the welding operation was tailor welded blank which in the next stage of processing was formed to produce a final part of an aircraft. Tailor welded blanks are made of dissimilar materials and as a result they have mixed properties of their constituent materials. Titanium Grade 2 provides good formability and can be used for those parts of a blank which are susceptible to cracking during a forming process. Titanium Grade 5 provides high strength. Electron beam welding is a fusion welding technology which is characterized by a high power density heat source, high quality of joints, a wide range of weld depths and a small heat input.For the purpose of the simulation finite element method was used. A thermo-elastic–plastic material model was assumed. The main difficulty in simulating the process of thin sheet welding is sheets’ tendency to significant deformation as a result of thermal expansion. In the paper different factors contributing to transverse and longitudinal bending were analyzed. It was shown that introduction of a welding gap into the model facilitates capturing transverse bending deformation. The impact of transverse bending on longitudinal bending was analyzed. The effect of mesh density and element type on transverse bending was analyzed. The calculated deformations were compared against the experimental results. The calculated temperature and stress fields were also presented.