Effect of the microstructure of IMCs and zinc accumulation on the mechanical properties of aluminum/galvanized steel joints in the VP-CMT process

Process stability and forming accuracy on wire arc additive manufactured Al–Zn–Mg–Cu alloy with different electrode positive/electrode negative ratios of CMT advance process

“…While the latter one was increased to the current level of the wait phase (Stage II). There are two reasons accounting for this current waveform in the SC phase of Stage II: (1) The heat input of the EN CMT cycle was lower than that of the EP CMT cycle, which deteriorated the wettability of the molten pool [11]. The increased current in the last section of the SC phase contributed to the well-off metal transfer process.…”

“…As for Stage II, the arc climbing phenomenon induced arc energy to be primarily applied to melt wire instead of the substrate due to the polarity change [14], so the molten pool was in a relatively 'cold' state with poor wettability. On the other hand, the heat input in Stage I was higher than in Stage II, which also improved the wettability of the molten pool in Stage I. lower than that of the EP CMT cycle, which deteriorated the wettability of the molten pool [11]. The increased current in the last section of the SC phase contributed to the well-off metal transfer process.…”

“…(2) The lower heat input in the EN CMT cycle also made difficulty on the arc reignition of the subsequent CMT cycle, this high current in the SC phase was useful to suppress this problem [11].…”

“…The EP/EN ratio is the key process parameter in the CMT advance process, which affected welding current/arc voltage waveforms, arc/metal transfer behaviours, molten pool flow, and heat input. The effect of the EP/EN ratio on the microstructure and related mechanical properties of weld joints was studied [11][12][13]. Wang et al [12] welded the Mg/Al dissimilar metal with different EP/EN ratios, and the thickness of the intermetallic compounds (IMCs) layers was reduced with decreased EP/EN ratio from 4:1 to 1:4.…”

Investigation of heat input effects on the joint characteristics of CMT welded Aa6061 sheets

“…At present, many fusion welding methods employed in the industry expose the high heat energy that creates unnecessary problems during welding of low melting alloys such as aluminium, magnesium and copper. 1,2 Therefore, Fronius Austria developed Cold Metal Transfer (CMT), a welding process to control the excess heat input, preferably suited for joining (low melting alloys) aluminium alloys by low heat input with the stabilised metal transfer. In addition, high-speed digital control strategies are being used to govern the metal transfer and arc length through advanced wire feed mechanisms in this welding process.…”