Wear and Corrosion of Wrought A6061 Aluminium Alloy in DOT3 Brake Fluid

The twofold impact of wear and corrosion on wrought A6061 alloy in hydraulic DOT3 brake fluid environment was studied. The wear studies were performed on the samples using a developed wear-jig. Weight loss corrosion test method was used to determine the corrosion rate of the wrought A6061 alloy samples immersed in the brake fluid for a total of 1680 hours. From the results of wear tests carried out on the A6061 alloy sample with brake oil, the highest wear value of 5.24x10-7 mg/mm2/cycle (approx.) was obtained from 6 N (approx) force after 130 minutes. The wrought A6061 alloy material demonstrated the highest corrosion rates nearly 3.0 x10-2 mg/mm2/yr within the early 168 hours of immersion in brake fluid. The result is practically lower than the corrosion rate of cast specimen in DOT3 brake oil or some other alloys immersed in other corrosive media that were previously reported in the literature. The results show that small amount of chemical corrosion is sufficient to cause and accelerate mechanical wear of the material in usage.

Effects of Si Content on the Tensile Strength and Machinability of Al-Mg-Si-Cu-Mn-Cr Alloys

This study investigated the effects of the Si content on the tensile properties and machinability of 6xxx−series aluminum alloys for application in hydrogen container valve housing. Four types of extruded Al−Mg−Si−Cu−Mn−Cr alloy specimens with different Si contents of 0.6−3.0 mass% were prepared. The effects of the Si content on characteristics such as microstructural features, tensile strength, and drill machinability were examined and compared with those of a commercial A6061 alloy. These specimens were found to exhibit different microstructures, tensile strengths, and chip segmentation behaviors after T6 heat treatment. These results were attributed to the interaction of the amount of second phase particles and solid-solute Mn and Cr with changes in the Si content.

Effect of ECAE on Structure and Strength of Porous A6061 Alloy with Aligned Unidirectional Pores

Deformation behavior of porous aluminum alloys with aligned unidirectional pores through equal-channel angular extrusion (ECAE) was investigated. The porous aluminum alloys were fabricated by dipping pure aluminum pipes into semi-solid slurry base metal. The pipes did not detach from the base metal even through the ECAE process. Comparing the sample dimension of pores before and after ECAE process, the amount of decrease in a dimension of pores was 19.4% in this study. The Vickers hardness increased by work hardening. Especially, the hardness value of area where plastic flow arose increased significantly. These results show that we can improve the mechanical properties with maintenance of the porous structure and measure the amount of the sample deformation quantitatively.

Effects of Surface Modification of SiC Nanoparticles and Preparation Process on Microstructures of SiCp/A6061 Alloy Matrix Composites

SiC nanoparticles (40nm) reinforced metal matrix composites (MMCs) were made by a common stir casting technique in two different preparation processing routes. In the first route, the coated ceramic powder was prepared using electroless plating to coat SiC nanoparticles by Cu. In the second route, Cu and SiC nanoparticles were fully mixed by high energy ball milling, and then SiC nanoparticles were embedded in Cu to form a “jujube-cake” structure. In both cases the average particles size were 0.2μm. The SiC nanoparticles enhanced A6061 alloy matrix composites were made by stir casting, and as-cast microstructures were studied by means of optical microscopy (OM) and scanning electron microscopy (SEM). The results show that in the first route, the Cu off and the slagging reaction occurs to form a mixture at the upper part of the ingot by a vacuum melting and the ingot central also has a large number of pores, only the lower part of the ingot organization is uniform. The second route can make better uniform composites.