Abstract
Due to its high efficiency, cold metal transfer (CMT) arc additive manufacturing presents considerable potential in the aluminium alloy additive manufacturing industry. However, during CMT arc additive manufacturing, the surrounding air environment promotes the lateral flow of liquid aluminium and the instability of the molten pool, reduces the surface quality and material utilisation of deposition walls, and causes internal hydrogen pores and coarse columnar grains, which negatively affect the structure and mechanical properties of the deposition walls. This study developed a CMT arc additive die manufacturing process to control the substrate material and deposition path to improve the physical properties of the deposition wall. The experimental results indicated that the copper plates can affect molten pool flow and material formation in the additive process, minimise hydrogen pores, and refine columnar grains. The porosity dropped from 2.03% to 0.93%, and the average grain size decreased from 16.2 ± 1.4 to 13.6 ± 1.3 μm, thereby enhancing the structure and mechanical properties of the deposition wall to attain standard additive manufacturing products.
Highlights
IntroductionIt is common to use the arc additive manufacturing technology to prepare nickel-aluminium intermetallic compounds or nickel-based alloys [1, 2]
Arc additives present a wide range of applications in the engineering manufacturing
The bottom of the molten pool is in contact with the upper layer of the weld, and other parts are in direct contact with the air. e average cooling rate of the molten pool is relatively low, and the air present in the molten pool cannot rapidly escape from the deposition wall before it solidifies, which leads to the formation of more pores in the deposition wall
Summary
It is common to use the arc additive manufacturing technology to prepare nickel-aluminium intermetallic compounds or nickel-based alloys [1, 2]. Productive additive manufacturing processes are pursued by manufacturing industries [3]. Pore defects are considered the main problem of aluminium alloy arc additive manufacturing [5]. Aluminium alloy pores mainly result from hydrogen, and the correlation between the number of pores and hydrogen-containing molecules is approximately linear [6]. E middle area of the deposition wall mainly constitutes uniform equiaxed grains along the generation direction [9]. When the number of deposition layers increases, due to thermal cycling, columnar grains increase and grow along the generation direction [10]
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