Joint evolution and strengthening mechanisms in arc brazed galvanised steels with Cu97Si3 filler.

Galvanised steel sheets have been joined using an arc brazing processing technique with Cu97Si3 as the filler metal. Gas metal arc (GMA) brazing and gas tungsten arc (GTA) brazing tests were conducted in flowing argon and with varying process parameters. Excellent wetting between base material and filler was observed in all samples. Tensile specimens fractured at the base material in samples prepared using optimal brazing parameters. Microhardness tests performed on the cross-sections of joined samples indicated that joint zone hardness is higher than base material or copper filler. Examination using energy dispersive X-ray analysis revealed the presence of intermetallic compound Fe5Si3(Cu) in the joint as well as a small amount of copper inside the base material. The dispersal of fine Fe5Si3(Cu) particles in the joint is the main strengthening factor. The Fe5Si3(Cu) particles were determined to arise from three sorces: whiskerlike fragmentation, dissolve-separation, and anode spot action. MST/6157 [ABSTRACT FROM AUTHOR]