Processing Parameter Control of Lifetime-Limiting Failure Mechanisms in Al-Si Cast Alloys at Room and Elevated Temperatures
Aluminum-silicon cast alloys widely used throughout the transportation sector, A356, 319, and A390, have been studied with respect to chemical compositions and processing parameters that control the resultant mechanical behavior. First, the development of strengthening mechanisms is discussed in terms of the role that alloying elements, solidification behavior, and thermal treatments play. Based on this understanding, an extensive matrix of material conditions was developed and characterized in order to provide practical guidelines for alloy development. In order to provide an understanding of lifetime-limiting failure mechanisms, fatigue crack growth and hot compressive dwell behaviors were further investigated. Fatigue crack growth tests were conducted for all alloys at R = 0.1 and room temperature, and creep–fatigue of 319 was studied at R = − 1.5 and 250 °C. The role of processing parameters in controlling the mechanical properties is identified and discussed, and recommendations for optimized design are made.
This work was supported by the National Science Foundation (Grant Number 1151588) and the members of the Integrative Materials Design Center (iMdc) at Worcester Polytechnic Institute. Special thanks to Dr. Fred Major and Peggy Jones for their helpful input and discussions.
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