Characterization the contribution and limitation of the characteristic processing parameters in cold metal transfer deposition of an Al alloy

Abstract

Cold metal transfer (CMT) depositing processes in aluminium alloy were conducted using various characteristic parameters which represent for the control of current output and wire motion. The effects of characteristic parameters on the energy input characteristic, metal transfer behavior, weld geometry, and microstructure of deposited weld metal were investigated. There were some limitations for characteristic parameters to achieve stable CMT process. For stable CMT process, the three distinct energy input periods of CMT cycle were controlled by characteristic parameters and thereby affect the features of deposited weld metal. The speed of wire feed motion affected not only burn phase duration but also short-circuiting duration. With the increased speed of wire feed motion, the whole energy input first increased and then decreased; the weld width and contact angle decreased, which was different from the effects of other characteristic parameters. An increment in short-circuiting current resulted in an increase in dilution ratio and grain size of weld metal although whole energy input was essentially constant. In conclusion, adjusting characteristic parameters can control the energy input process coupled with metal transfer behavior to design and optimize the weld properties for each special CMT application, which is suitable for additive manufacturing of aluminium alloy.