Abstract
Coarse grains and gas pores are two main problems that limit the application of additive manufacturing aluminum alloys. To reduce porosity and refine grains, this paper presents a quantitative investigation into the effect of pulse frequency and arc current on the porosity and grains of arc additive manufacturing Al–5Si alloy. The experiment results show that pulse frequency and arc current have a significant impact on the macrostructure, microstructure, porosity, and tensile properties of the samples. Fine grains and a uniform microstructure can be obtained with low pulse frequency and low arc current as a result of the rapid cooling of the molten pool. With the increase of pulse frequency, density shows a trend that firstly escalates and attains the maximum value at 50 Hz, but later declines as a result of the relation between pores formation and gas escape. Moreover, better tensile properties can be obtained at low pulse frequency and low arc current because of the finer grains.
Highlights
Over the last few decades, researchers have already made great strides in metal additive manufacturing technologies [1,2,3], which can be classified by the employed heat source, including laser additive manufacturing, electron beam additive manufacturing, and arc additive manufacturing.Williams et al [4] pointed out that, compared with other additive manufacturing methods, arc additive manufacturing has distinct advantages: High manufacturing efficiency, low cost, and good structural integrity
Much more coarse ripples periodicare ripples are atobserved the surface under low under pulse frequency, as shown inasFigure coarse periodic ripples are at the surface low pulse frequency, shown3a,b
Al–5Si alloy samples were fabricated by arc additive manufacturing with different
Summary
Over the last few decades, researchers have already made great strides in metal additive manufacturing technologies [1,2,3], which can be classified by the employed heat source, including laser additive manufacturing, electron beam additive manufacturing, and arc additive manufacturing. Some recent studies have been devoted to the process parameters on the quality and properties of arc additive manufacturing aluminum alloy [11,12]. The main reason that limited the aluminum’s application of additive manufacturing is that gas pores and coarse grains form during arc additive manufacturing, which largely reduce the mechanical properties of aluminum alloys [13,14,15,16]. Materials 2018, 11, 1344 pure argon flow rates in order to reduce the pores and obtain refine microstructure in arc additive manufacturing of Al–Cu alloy [17,18]. In this study, the effect of pulse frequency and arc current on the gas pores and grains has been systematically investigated. The mechanism of reducing porosity and refining grains was revealed by adjusting the pulse frequency and arc current. The geometry, microstructures, and tensile properties under different pulse frequencies and arc currents will be investigated
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