Characterisation of the cold metal transfer (CMT) process and its application for low dilution cladding

Abstract

a b s t r a c tThe process characteristics of the synergic cold metal transfer (CMT) process have been examined for welding aluminium alloy. Utilising a simple backlighting system and through the arc monitoring the droplet transfer modes were identified. Whilst the modified short circuit mode was evident for the lower parameter range, a two part transfer mode based upon a combination of spray and short circuit transfer was observed for the mid to upper parameter range. The technology was also explored as a cladding process for applying to ternary alloyed (Al-Cu-Mg) aluminium plate. This alloy system is known to be susceptible to solidification cracking when MIG welded using the binary Al-2319 (Al-Cu) filler wire, this being due to the wide element freezing range of the weld resulting from mixing with the base material. Utilising this filler, weld dilution ratios for both CMT and pulsed welding were identified across the examined parameter range. The CMT process exhibited greater control of dilution that enabled deposition of a quasi-binary (Al-Cu) layer exhibiting a less crack susceptible composition. Onto this layer conventional MIG welding could be applied which could potentially eradicate cracking using a binary filler wire.

Analysis of Phase Transformations in Inconel 625 Alloy during Annealing

“…To the key benefits of the CMT method belong very low heat transmission to the base metal, high process speed, very low spatter, as well as precision control of the welding arc and its stability. These CMT features allow for producing high quality weld overlays on steels [14,15].…”

Erosive Wear of Inconel 625 Alloy Coatings Deposited by CMT Method

“…Traditional welding processes, such as the MIG/MAG welding technique, are characterized by relatively little capability to control the heat delivered to the substrate and, as a consequence of which, the iron content of the weld clad is too high [11]. The CMT (Cold Metal Transfer) technique [11,12] has turned out to be an alternative and, at the same time, innovative weld cladding method. However, a lot of conducted research studies point out to the need for developing a high-temperature method for erosive wear testing of constructional materials, protective coatings and refractories [9,13,14].…”

Características de fusão e potência de soldagem com a transferência MIG - CMT versus MIG convencional para Alumínio 5183

“…Dessa forma, o processo pode ser bem caracterizado como sendo intercalações de "quente e frio" [5], mas não necessariamente um processo "frio" em seu conjunto, como seu nome sugere. Esta combinação de potência alta e baixa é como se fosse uma corrente pulsada de onda retangular e, com a associação do retrocesso do arame, propicia uma transferência de gota metálica por tensão superficial de maneira muito suave, estável e regular [6] [7]. Essa tecnologia também se mostra eficaz na redução de respingos.…”