Wire-arc additive manufacturing of Al-Mg alloy using CMT and PMC technologies

Abstract

Among the several metallic additive manufacturing (MAM) technologies available, the wire-and-arc based ones are very beneficial due to the lower operational costs, higher efficiency use of raw materials, and high deposition rates achieved. The Cold Metal Transfer (CMT) process stands out by the lower heat input compared to the other wire-and-arc based methods. On the other hand, processes such as Pulse Multi Control (PMC) and its variants have not been tested yet in additive manufacturing and for this reason they should be evaluated. Therefore, considering the technologies potential and the need of automotive and aeronautical industry of manufacturing parts of complex and optimized geometry in a faster way, the study of these technologies is very relevant. Thus, the objective of this paper is the additive manufacturing of walls with Al-Mg alloy using CMT, CMT-Pulse, PMC, PMC-Mix, and MIG-Pulse, and the evaluation of the hardness, mechanical strength, and porosity of the manufactured parts aiming future industrial applications. The results showed good mechanical properties, small pore fraction, and geometric uniformity of parts produced with PMC and PMC-Mix. MIG-Pulse and PMC parts presented the smaller pore fraction among the GMAW variants, although no difference was noticed in the mechanical properties of the parts.

Maximising the Deposition Rate of 5356 Aluminium Alloy by CMT-Twin-Based WAAM While Reducing Segregation-Related Problems by Local IR Thermography

“…However, in a real part, those defects must be avoided, because the BTF ratio increases as the effective area decreases (Table 5). Obtained tensile values are similar to the ones revealed for WAAM in other works [8,29,35] and higher compared to the main providers' material specifications. Moreover, taking into account the average of the obtained mechanical properties (Table 12) for the different interpass dwell times, they reveal deviations of less than 3 Mpa, which means that the used interpass dwell times do not induce substantial differences in the microstructure apart from the appearance of segregations in the outer zones.…”

Wire Arc Additive Manufacturing (WAAM) for Aluminum-Lithium Alloys: A Review

“…Some studies focused on the modification of variables in the process of reducing humps. Cold metal transfer (CMT) technology for Al-Mg alloy shows that a one-way continuous-arc trajectory presents better regularity in the part geometry, owing to the unique starting point imposed in this case; on the contrary, when using other ways, humps are formed, affecting the frequency of the deposits [ 96 ].…”

“…Consistently, good penetration is guaranteed, there is less undercutting, and it is possible to weld more quickly and more cost-effectively. PMC Mix technology combines this pulse-controlled transfer to cycles controlled short-circuit, generating a colder phase and reducing the heat input even more [ 96 , 112 ].…”

“…Gomes et al [ 96 ] also compared the PMC and CMT techniques for Al alloys. The porosity was smaller than 175 µm in diameter and was dispersed in both cases.…”

Investigation of microstructure, hardness and residual stresses of wire and arc additive manufactured 6061 aluminium alloy

“…In the literature, a substantial work on AM of aluminium alloys with PBF-Laser technique shows that all types of aluminium alloys are printable using this particular process [16]. In contrast, recent studies on WAAM show that only specific 2XXX [17][18][19][20][21][22][23][24][25], 4XXX [26][27][28][29][30] and 5XXX [20,22,27,28,[30][31][32][33][34][35][36] series can be successfully deposited. Thus, an upstream development is absolutely required to obtain WAAM-built parts using 6XXX and 7XXX series of aluminium alloys [37,38].…”