Abstract
Diffusion bonding of aluminum bronze to austenitic stainless steel was performed with a phosphor bronze foil as an insert metal. The joints were fabricated at temperatures lower than the solidus temperature and also they were fabricated at temperatures between the solidus and liquidus temperatures of the phosphor bronze (solid-liquid bonding). Influences of bonding time, bonding temperature, bonding pressure and roughness of bonding surface on the joint tensile strength and the fatigue strength have been investigated. Main results obtained are as follows;
(1) In the solid-liquid bonding, Sn-riched liquid arose in the phosphor bronze and then it was discharged to the outside of the joint with increasing the bonding time at higher bonding pressures. At lower bonding pressures, however, the liquid stayed in the phosphor bronze and the fused structure in which voids were forms in the cooling process of the bonding operation was observed in the bond zone.
(2) When the volume fraction of the fused structure was around 1%, the joint tensile strength took the maximum value. The strength was decreased with the increase in the amount of the fused structure.
(3) The maximum joint strengths for the constant bonding load of 1 MPa and restrained bonding were 415 MPa and 465 MPa, respectively.
(4) The joint strength increased with the decrease of roughness of the bonding surface, and the maximum strength obtained was 515 MPa at Rz 0.04μm.
(5) The endurance ratio of the joints bonded at temperatures lower than the solidus temperature of the phosphor bronze was 36 to 46%, but it was higher than 50% for the solid-liquid bonding.
