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Field inspection of 41 vehicles equipped with magnesium clutch housings or transfer cases was carried out after service in Nova Scotia or Prince Edward Island for periods up to five years. This area is reported to be the most severe location in North America for salt-induced corrosion of automobiles. The die cast magnesium components were unpainted, but basic measures were taken to control galvanic corrosion. The clutch housings had the longest history, with production spanning the years 1982-1987. The general surface corrosion of these housings was negligible, notably less than that of die cast aluminum 380 or carbon steel components on the same vehicle. Slight galvanic corrosion of exposed bolt bosses was observed, induced by the plated bolt. Some galvanic action was noted at the face-to-face junction between the magnesium clutch housings and aluminum 380 transmission cases. This was not sufficiently advanced to indicate a threat to component function.

Selected metallic platings and insulating coatings on steel fasteners were evaluated for ability to reduce galvanic corrosion of die cast magnesium in a modified salt spray test. Proprietary electroplate systems based on zinc, zinc-nickel, zinc-cobalt and tin-zinc were tested, along with a commercial 50-50 tin lead alloy electroplate without supplementary coating. A proprietary liquid-applied zinc-rich inorganic coating successfully used on automotive fasteners was also tested for compatibility with magnesium. Encapsulation of bolt heads with plastic insulating coatings or special molded caps was evaluated. Interruption of the continuous salt spray by rinse and bake cycles was investigated as a likely exposure condition for magnesium assemblies in powertrain or underhood applications. Several of the protection schemes were found to effectively eliminate galvanic corrosion of the magnesium.

A through-process methodology for numerical simulations of the structural behavior of thin-walled cast magnesium components is presented. The methodology consists of casting process simulations using MAGMAsoft, mapping of data from the process simulation onto a FE-mesh (shell elements) and numerical simulations using the explicit FE-code LS-DYNA. In this work, generic High Pressure Die Cast (HPDC) AM60 components have been studied using 3-point bending and 4-point bending tests. The experimental data are applied to obtain a validated methodology for finite element modeling of thin-walled cast components subjected to quasi-static loading. The cast magnesium alloy is modeled using a user-defined material model consisting of an elastic-plastic model based on a non-associated J2-flow theory and the Cockcroft-Latham fracture criterion. The fracture criterion is coupled with an element erosion algorithm available in LS-DYNA.

A specific objective of the European Mg-Engine project is to qualify at least two die cast Mg alloys with improved high temperature properties, in addition to satisfactory corrosion resistance, castability and costs. This paper discusses the selection criteria for high temperature alloys leading to four candidate alloys, AJ52A, AJ62A, AE44 and AE35. Tensile-, creep- and fatigue testing of standard die cast test specimens at different temperatures and conditions have led to a very large amount of material property data. Numerous examples are given to underline the potential for these alloys in high temperature automotive applications. The subsequent use of the basic property data in material models for design of automotive components is illustrated.