Influence of zinc on intermetallic compounds formed in friction stir welding of AA5754 aluminium alloy to galvanised ultra-high strength steel

In this study, lap joints between AA5754 and DP1000 ultra-high strength steels were produced by friction stir welding. In order to investigate the roles of zinc on intermetallic phase formation and joint properties, steel substrates were used, two being galvanised coated and one uncoated. Joint performance has been evaluated in term of maximum tensile shear loading. The effects of the process parameter, translational speed; chemical compositions; and intermetallic phase formation on the mechanical properties have been investigated. The results show that joints with a galvanised layer exhibit higher strength as compared to the non-coated steel. A thicker galvanised layer promotes the presence of zinc in the aluminium matrix, resulting in better joint properties. The level of zinc contents in the aluminium matrix depends on process temperature and material circulation characteristics. Two stable Al-rich intermetallic phases, Al₅Fe₂ and Al₁₃Fe₄, were detected at the interface regardless of the coating conditions.     

Interactive Effects of Silicon and Soil pH on Growth,Yield and Nutrient Uptake of Maize

Silicon - Priming crop seeds with silicon (Si) to withstand various abiotic stresses is a novel approach. As soil pH affects dissolution of Si pools and Si uptake by plant, evaluation of this...     

Intermetallic compounds in friction stirred lap joints between AA5754/galvanised ultra-high strength steel

This paper presents results of joining of AA5754 and DP800 based on the friction stir welding process. Joints were produced by the tool made of H13 tool steel which was allowed to penetrate through the aluminium sheet until reaching the surface of steel sheet without penetrating into it. This approach is an economic and robust way to operate the dissimilar welding process without excessive tool cost. Bonding was achieved by interfacial diffusion reactions between aluminium and iron with a formation of intermetallic compounds. The formation of brittle intermetallic compounds at the interface between the materials was studied. Three intermetallic phases were found at the interface including Al₁₃Fe₄, Al₅Fe₂ and Fe₃Zn₁₀. A range of process parameters was identified with a thickness of the intermetallic layers around 2?µm. Shear fracture failure mode was observed under overlap loading. The mechanisms of formation of the joints and factors controlling the strength were discussed.