Description
In an effort to determine the best course for developing die cast alloys with improved creep resistance, the creep behavior of existing commercial alloys is being studied. For many automotive applications under consideration, such as bolted housings and covers, the critical loads are compressive. In spite of this fact, most creep testing has been performed in a tensile mode. In this study we compare the tensile and compressive creep behavior of die cast alloy AM60B at 150°C. The behavior is typical of magnesium alloys in this temperature range. For intermediate tensile stresses (20–60 MPa), a power law with a stress exponent n≈4 describes the stress dependence of the minimum strain rate. The same power law dependence is observed in compression, however, the rates themselves are about an order of magnitude lower. The presence of porosity in the die casting may explain this observation. Although the secondary creep rates at a given stress were slightly lower than those reported for AZ91D, there appears to be more transient creep.