Titanium Alloy Essay

Abstract
Titanium alloy, Ti-6Al-4V plate was diffusion bonded with AISI 304 stainless steel plate with silver foil as an intermediate layer at various temperatures for different holding period. The appropriate process parameters have been investigated to achieve good quality joints. The microstructures formed in the diffusion region were observed and determined by optical microscopy. The microhardness across and perpendicular to the interface were measured and the strength of the joints were also determined with lap-shear test. X ray diffraction analysis confirms the presence of intermetallic compounds present in interface regions. This paper focuses on the effect of process parameters on hardness, strength and diffusion layer thickness of

Bonded surfaces were ground by 1200 grit SiC paper and polished using diamond paste (2 µm) followed by cleaning in ethanol and acetone prior to diffusion bonding. Good bonding was achieved when the temperature used was between 700 to 8000c and holding time between 30 to 90minutes. The pressure was between 1 to 5MPa. Bonding separated when the temperature used was less than 7000c and above 8250c. Successful bonding happened when the holding time was between 30 to 90minutes and bonding was also successful at 120minutes. But de-bonding of coupons happened which was bonded at a holding time of 120minutes during specimen preparation for the conduct of lap shear test. After choosing the factors and levels, Box Behnken design was used to perform experiments as shown in Table 3. The Box-Behnken design is an independent quadratic design in that it does not contain an embedded factorial or fractional factorial design. In this design the treatment combinations are at the midpoints of the edges of the process space and at the center. These designs are rotatable (or near rotatable) and require 3 levels of each factor. The number of experiments conducted is much lesser compared to a central composite