Repairing 2024 Aluminum Alloy via Electrospark Deposition Process: A Feasibility Study

Abstract

e electrospark deposition (ESD) technique has been studied as a potential method to repair locally damaged 2024 rolled sheets supplied in natural-aged (T4) and artificial-aged (T6) conditions. e 2024-T4 and 2024-T6 tensile samples were first notched, and then the notches were filled (repaired) by ESD with the same aluminum alloy. e effect of process parameters on the microstructure of the filling material and the substrate properties was studied by optical and scanning electron microscopy. Tensile and hardness tests were performed. e tensile test showed that T4 and T6 as-repaired specimens had low tensile properties, which was due to defectiveness and residual stress caused by high cooling rate during reparation. However, the asrepaired specimens were heat-treated at either 135°C or 190°C to improve the mechanical properties. A better yield strength was observed for the T4 heat-treated alloy. e ductility and ultimate tensile strength did not change, being mainly affected by voids and microcracks.

Effect of ElectroSpark Process Parameters on the WE43 Magnesium Alloy Deposition Quality

“…Generally, during the ESD process the cooling rates may reach 10 5 -10 6 • C/s [22,23]. Furthermore, the bond interfaces with the previously deposited material are not observed, unlike what was found for deposits via ESD in light alloy [19,31,32].…”

“…The perpendicularly cracks can arise in the first deposited layers, in the subsequent ones or nucleate on random shaped defects inside the deposits [38]. Usually, during the deposition process these cracks propagate upwards owing to repeated thermal stress [31,32]. Instead, the parallel cracks to the interface, also known as delamination cracks, can be generated by poor mixing of the electrode material with the substrate or layer previously deposited (weakly bounded interfaces) or by the mechanical impact of the electrode tip to the workpiece [31,39].…”

“…The main defects detected in the deposits occur as voids of different morphology: spherical or random shaped defects (n • 1 e n • 2, respectively) and laminar defects (n • 3) that extend both perpendicularly and parallel to the substrate/deposit interface. The spherical or random shaped defects are believed to be the result of the amount of material brought to melting and its distribution [25,31,32,37]. While generally, the formation of laminar shaped defects was considered as a normal consequence of thermal stress induced by the high thermal gradients inherent to the ESD process.…”

“…Some studies have analyzed both microstructure and defects of 2024 aluminum alloy coatings deposited onto a homologue substrate by ESD process [19,31]. Moreover, the effect of the ESD process as a repair technology was studied by P. Leo et al [32] and P. D. Enrique et al [33] respectively for a 2024 aluminum alloy and Ni-Superalloy. Especially, regarding the aluminum alloy, a comparative study between deposits performed on substrates supplied both in natural aged and artificial aged state has been performed.…”

Properties of AlB$_{12}$–Al Electric Spark Coatings on D1 Aluminium Alloy

“…As shows possible to eliminate the defects by applying of coatings with the use of concentrated energy flows: surface strengthening with ion implantation, ion-plasma spraying, micro arc oxidation, plasma electrolytic oxidation, anodizing, laser processing, and electric spark alloying (ESA) [4,[9][10][11][12][13][14][15][16]. One could say that ESA is a quite efficient (in a number of parameters) technique enabling, in general, simply to apply the coatings (with various materials) on the details surfaces, in particular, aluminium alloys.…”