Journal of Welding Science

Despite rapid advancement of additive manufacturing methods in recent years, sufficient research on bonding of additively manufactured materials to conventional alloys has not been conducted. This study evaluates the bonding between austenitic stainless steel L316 and Ti-6242 alloy, fabricated by electron beam melting, using the transient liquid phase (TLP) bonding method. The TLP bonding was achieved using a copper interlayer and processing in a vacuum furnace, examining the effects of process time and surface roughness on bond quality. The samples were characterized by optical and scanning electron microscopy, X-ray diffraction, shear strength testing, and surface roughness measurement. Results showed that reducing the surface roughness increased the shear strength. Additionally, processing time significantly affected the element diffusion, formation of intermetallic compounds like FeTi and TiCu, and the shear strength of the joints. The highest shear strength of 200 MPa was obtained with surface preparation by grinding and polishing and bonding at 980°C for 120 minutes.

Eutectic tin-zinc solder can be a suitable replacement for tin-lead solder due to its low cost, suitable melting temperature, and desirable mechanical properties. However, due to the high vapor pressure of zinc, manufacturing this alloy using the melt method is very difficult and expensive. In this study, Sn-8.9%Zn lead-free solder was fabricated using the angular accumulative extrusion method of tin sheets and zinc powder in 10, 12, and 15 passes, and characterized. Microstructural investigations were performed using optical and scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction spectroscopy. The shear strength and hardness of the solders were also measured. The results showed that after 12 passes, the dispersion of zinc powder in the tin matrix was improved, and the dissolution of zinc was confirmed by a decrease in the XRD peak intensities. However, after 15 passes, cracks appeared in the structure. The shear strength of the tin-zinc solder joint was about 60% higher than that of commercial tin-lead solder. The wetting angle of this solder on copper was measured to be 21 degrees, and its electrical resistance was measured to be 4.1 nanoohms, which is within the acceptable range for electronic applications, although it has a weaker performance compared to tin-lead solder.