Effect of Substrate Alloy Type on the Microstructure of the Substrate and Deposited Material Interface in Aluminium Wire + Arc Additive Manufacturing

Abstract

Wire + Arc Additive Manufacture is an Additive Manufacturing process that requires a substrate to initiate the deposition process. In order to reduce material waste, build and lead time, and improve process efficiency, it is desirable to include this substrate in the final part design. This approach is a valid option only if the interface between the substrate and the deposited metal properties conform to the design specifications. The effect of substrate type on the interface microstructure in an aluminium part was investigated. Microstructure and micro-hardness measurements show the effect of substrate alloy and temper on the interface between the substrate and deposited material. Microcracks in the as-deposited condition were only found in one substrate. The deposited material hardness is always lower than the substrate hardness. However, this difference can be minimised by heat treatment and even eliminated when the substrate and wire are made of the same alloy.

Mechanical performances of the interface between the substrate and deposited material in aluminium wire Direct Energy Deposition

“…The study of the 2219 substrate and 2319 WAAM deposit combination enabled a focus on microstructural features, while the 2024 substrate and 2319 WAAM combination provided an outlook on challenges occurring when using dissimilar alloys. -As shown in previous work [14], the substrate microstructure, especially grain size, can impact defect formation in the partially melted zone. To investigate this phenomenon on the mechanical performance, two substrates made of the same alloy were selected, one conventionally made and one rapidly solidified.…”

“…Heat treatment was carried out for the 2219+2319 and 6061+2319 combinations as these alloys have the same solution treatment temperature. The issues occurring during the heat treatment of the 2024+2319, due to the low melting point of the 2024 alloys were previously reported [14] The tensile specimens were machined, as shown in Fig. 1.…”

“…Zhang et al [12] studied the fatigue behaviour of a Ti6Al4V interface; Gu et al [13] investigated the microstructure and tensile properties of aluminium interfaces focusing on the effect of deposition parameters and post deposition heat treatment. Eimer et al [14] reported microstructure observation of the interface between aluminium deposit and four 2000 series aluminium alloys, but no mechanical testing was carried out.…”

“…This paper aims to assess the possibility of integrating the substrate in an aluminium WAAM component. Several phenomena are well known from welding metallurgy, including softening of the Heat Affected Zone (HAZ) [22,23], alloying element segregation in the partially melted zone [24][25][26], and hot cracking in the fusion zone [27][28][29], could affect the mechanical performance of the interfaces, as reported by Eimer et al [14].…”

Review of Aluminum Alloy Development for Wire Arc Additive Manufacturing

“…Heating of the feedstock wire prior to deposition was attempted to reduce porosity and increase production efficiency [30]. The importance in selection of substrate build material was highlighted by Eimer et al [94].…”