Laser Welding Of Titanium Alloy And Stainless Steel

In this paper, we are conduct a series of laser welding on TA2 and 304 stainless steel. Moreover, we compared the influence of different component. In order to get the control method of dissimilar metal welding quality, we compared transition metals with different width and different process parameters on the microstructure and properties of the joint. The following methods were used in this paper: optical microscopy; scanning electron microscopy(SEM), X-ray diffraction(XRD) on the microstructure analysis; tensile strength; micro hardness of joints; simulating the titanium/steel butt welding and 5mmCu/V transition section indirect but welding temperature field and stress field. The final result was verified by experiment.Because of the formation of a large number of series of brittle Ti-Fe compounds, the weld crack after TA2/304 directly butt welding and the fracture was occurred in the side of steel. Based on the key of the welding quality, the idea that the solid solution instead of the metal compound is put forward at the interface.In this paper, firstly, we used V as the transition metals to connect the TA2 and 304 stainless steel. When the width of V were used 2mm, 3mm, 4mm, 5mm wide, it can be effective connect the Ti and Fe. The joint is consisted by TA2/V, pure V and V/304 stainless steel. Each interface is only solid solution. When the transition section’s wide is 5 mm, we get the highest joint strength of 314.25 MPa. When we added 1mmV, the joint cracked after weld because the brittle compound is formed in the middle. When separately added 2mm-5mm wide Cu/V transition section, the joint is consist five parts of TA2/V weld, pure V zone, V/Cu weld, pure Cu zone, Cu-304 stainless steel. The highest strength of the joint strength is 5mm transition section, for 297.35 MPa. When the 1mmCu/V transition layer is used, there is no vanadium layer in the middle of the two welding seam. The fracture originated from this, the joint strength is 135.8MPa. Based on the 1mmCu/V, when the reduction of the V layer width is 0.5mm, the thickness of the layer of the non fusion vanadium layer is decreased, and the tensile strength is 243.3MPa. On the base of reducing the V layer thickness, the second laser beam to the copper side offset 0.1mm, and the strength of the joint come to 251.5MPa.The simulation results shows that the temperature rise and fall are very fast during the laser welding process. The process of weld solidification is an extreme non-equilibrium process. The results of direct butt welding stress shows that the maximum tensile stress exists in steel lateral interface compound area. With good plasticity, low yield strength, the Cu reduces the accumulation of stress. The final stress distribution is more uniform than the direct welding. which explains the key to improve the performance of the joint is to optimize the organization and improve joint plasticity.