Gas metal arc brazing of galvannealed steel sheets

Abstract

An advanced gas metal arc welding technique with controlled short-circuiting mode of metal transfer and arcing at low power was employed for brazing of galvannealed steels using CuSi3 filler wire. The brazed joints showed the presence of an interface layer with Fe–Si intermetallic compounds (IMC). Increase in heat input resulted in an increase of the interface layer thickness. The maximum failure load of 2.5 kN was achieved for a heat input of 105 J mm⁻¹ with the corresponding interface layer thickness of 2.7 µm. Heat inputs beyond 105 J mm⁻¹ led to excessive spatter of zinc and increase in interface layer thickness with hard Si-rich IMC. In contrast, heat input values lower than 80 J mm⁻¹ produced inadequate wetting of the steel surface by the molten filler wire deposit and resulted in low joint strength.

Keywords:

• Gas metal arc brazing
• Controlled short-circuiting
• Galvannealed steel
• Bead profile
• Joint strength