Correlation of Tensile Properties and Interfacial Structures in Ferrite Stainless Steel Joints Brazed Using Cu-Based Filler Metal

The effect of interfacial structures on the tensile properties of ferrite stainless steel(429EM) joints brazed using a Cu-based filler metal such as Cu-6.4Si and Cu-13.3Al is investigated. The brazing current is varied from 80-120A at a brazing speed of 800mm/min. The change in interfacial structure with changes in the insert metal and the brazing current is observed using optical microscopy, SEM/EDX, EBSD, FIB and TEM and the mechanical properties of the joints are evaluated by a tensile shear test. The hardness of the fusion zone, the interface, and the base metal is measured using a micro-Vickers hardness tester and a nano-indenter. Furthermore, a relationship among interfacial structure, fractured type and tensile properties is discussed and the interfacial structure is examined for a coherent or noncoherent interface between the base metal and the interface phase

Key Words : Arc Brazing, Ferrite Stainless Steel, Cu-6.4Si, Cu-13.3Al, Interfacial Structure, Tensile Properties, Hardness, Coherent structure, Noncoherent structure