INFLUENCE OF BONDING PRESSURE ON THE DISSIMILAR JOINTS OF TITANIUM AND STAINLESS STEEL WITH AN ALUMINUM INTERLAYER

In present investigation diffusion bonded joints between titanium (Grade 2) and stainless steel (X5CrNi18-10) using 120 mu m thick aluminum foil as a filler metal were produced at 600 degrees C for 60 minutes under: 2, 4, 6 and 8 MPa pressure in vacuum. The microstructure was investigated using light optical microscopy and scanning electron microscopy equipped with an energy dispersive X-ray system (EDS) to determine chemical composition of the joint. Joinings between dissimilar materials result in formation of intermetallic phases in the interface. The FeAl3 and Fe2Al5 intermetallic layers were observed at the stainless steel-aluminum interfaces. At the aluminum-titanium interfaces TiAl2 intermetallic layers were identified. The investigation shows that the pressure is important factor to control mechanical properties of diffusion bonded joints. The highest shear strength (88 MPa) was achieved for samples prepared using the highest pressure value, and for those samples were performed corrosion resistance test in 3 % sodium chloride solution. The samples were kept in the solution for 24, 48, 72 and 96 h. Corrosion resistance of the diffusion brazed joints was evaluated by the weight loss during the test.