Materials Science Forum Vol. 1129

Abstract: A positive segregation is usually formed on the casting surfaces produced by high-pressure die casting (HPDC). In diecast Al-Si-Cu alloy components, this segregation shows a higher content of Si compared to the nominal composition of the alloy and it drastically affects the anodizing response of the casting surface. In the present work, HPDC components were produced by AlSi11Cu2(Fe) alloy, grit-blasted, and then anodized in a sulfuric acid electrolyte at the temperature of -4.5°C. Before the anodizing process, some regions of the casting were also milled, in order to completely remove the surface segregation. Microstructural investigations were carried out on grit-blasted and milled surfaces to characterize the initial substrates before anodizing, and to study their effect on the growth of the anodic layer. Scratch and wear tests were also performed to investigate the surface mechanical properties after anodizing. The results show that the surface segregation and the rough surface present on grit-blasted substrate leads to the formation of a thin and homogeneous anodic layer. On the contrary, a thicker and scalloped oxide film is formed on the milled surfaces. After anodizing, grit-blasted surfaces show lower wear and scratch resistance than milled substrates. The presence of surface segregation prevents the thickening of the anodic layer, negatively affecting the surface wear resistance due to the reduced oxide thickness.

Abstract: The microstructure of Al-Mg-Si aluminium alloys is well characterised when it comes to the initial state of the cast billet or the artificially aged profile. Typically, a gas oven coupled with an induction oven is used to preheat the billets before extrusion. Preheating reduces the flow stress of the aluminium and dissolves the phases that have precipitated during cooling after homogenisation. In this paper, the influence of the gas oven temperature on the partial or complete dissolution of the precipitated phases will be shown. In addition, the negative effect of a wrong choice of parameters on the volume content of the MgSi phases will be shown.

Abstract: Aluminium alloys are being used more often as a result of industry demands for strong, lightweight materials. Because of its advantages over conventional fusion welding techniques, friction stir welding, or FSW, has become a promising technique for joining aluminium alloys. Nonetheless, there is still cause for concern regarding FSW joints' vulnerability to cavitation erosion, which is a major issue in applications exposed to harsh environments. The cavitation resistance of EN AW 1200 aluminium alloy joints made by the FSW process is the main objective of this study. By utilizing specialized equipment to conduct cavitation tests, the study uses a comprehensive methodology to assess the cavitation erosion behaviour of these joints. A number of variables are investigated in order to determine how they affect the cavitation resistance of the welded joints, including mechanical attributes, welding parameters, and microstructural features. The goal of the study is to shed light on how well FSW joints function and hold up in cavitation scenarios. This information will be useful in improving the dependability and suitability of EN AW 1200 aluminium alloy in sectors where the ability to withstand cavitation erosion is critical. The findings from this study are expected to contribute to the optimization of welding parameters and material selection, ultimately advancing the use of aluminium alloys in critical applications requiring resistance to cavitation-induced damage.