Control of mass and heat transfer for steel/aluminium joining using Cold Metal Transfer process

Abstract

The Cold Metal Transfer process is investigated to join zinc coated steel with aluminium alloy by braze-welding. A 4043 filler metal is deposited on the surface of the coated steel, and the effect of the current waveform on the metal transfer and the heat transferred to the base metal is investigated. The reduction in the ‘boost phase’ duration of the current waveform decreases the volume of liquid drops at the wire tip and allows to increase the short-circuit frequency, inducing a similar or higher deposit rate. Regular deposits are obtained when the linear energy remains below ∼500 J mm⁻¹. The heat transferred to the base metal, and thus the thickness of the intermetallic layer formed at the Al/steel interface, is lower for an equivalent deposit rate when the short-circuit frequency is high.

Keywords:

• Gas metal arc welding
• Cold metal transfer
• Aluminium-steel joining
• Metal transfer
• Heat transfer
• Intermetallic