Microstructure and bonding strength of tin-based Babbitt alloy on ASTM 1045 steel by MIG arc brazing

The effect of composition of welding wires on the interfacial microstructure and the bonding strength of Babbitt alloys and steel substrate has been studied. A cladding of Sn-based Babbitt alloys was obtained on the surface of medium carbon steel by MIG arc brazing. The microstructure of Babbitt alloys and the interfacial microstructure of the interface between Babbitt alloys and steel substrate have been systematically investigated. The bonding strength of Babbitt and steel substrate has been collected according to the destructive testing method of the bimetallic bonding strength of sliding bearing. Among the three samples, the BW8-4 and steel substrate without no SnSb segregation had the highest bonding strength (83.07 MPa).The reason for the enhancement of the bonding strength was discussed. The IMC layers were harder than the α-Sn matrix so that they can effectively prevent the crack between generating and expanding at the joint part. Then, the bonding strength can be enhanced a lot. However, in samples obtained by BW11-6 and BW8-8, the segregated SnSb phase near the junction which was hard and fragile would result in the concentration of stress. And the SnSb would also lead to the occurrence of brittle fracture in the segregation. So that the bonding strength had been greatly reduced.