Abstract
Due to their high strength-to-weight-ratio, magnesium alloys are very attractive for use in automotive engineering. For application at elevated temperatures, the alloys must be creep-resistant. Therefore, the influence of the operating temperature on the material properties under quasistatic and cyclic load has to be understood. A previous study investigated tensile-tensile fatigue behavior of the magnesium alloys DieMag422 and AE42 at room temperature (RT). The aim of this study was the comparison of both alloys regarding compression, tensile, and compression-compression fatigue behavior. The quasistatic behavior was determined by means of tensile and compression tests, and the tensile-compression asymmetry was analyzed. In temperature increase fatigue tests (TIFT) and constant amplitude tests (CAT), the temperature influence on the cyclic creeping (ratcheting) behavior was investigated, and mechanisms-relevant test temperatures were determined. Furthermore, characteristic fracture mechanisms were evaluated with investigations of the microstructure and the fracture surfaces. The initial material was analyzed in computed tomographic scans and energy dispersive X-ray (EDX) analyses.
Highlights
Due to their high specific strength, magnesium alloys represent an interesting alternative to materials conventionally used in automotive engineering with regard to reducing vehicle weight
Magnesium alloys have excellent castability and enable thin-walled and complex components to be produced by die casting
The results show clear differences in the cyclic deformation behavior for both alloys, which affect cyclic creeping behavior and lifetime at room temperature (RT)
Summary
Due to their high specific strength, magnesium alloys represent an interesting alternative to materials conventionally used in automotive engineering with regard to reducing vehicle weight.Magnesium alloys have excellent castability and enable thin-walled and complex components to be produced by die casting. For applications in the powertrain, it is necessary to use alloys that are resistant to creep forming at temperatures above 200 ◦ C. The alloy AE42 (Mg-4Al-2SE), which contains rare earth (RE) as alloying elements, is used in the powertrain and has good creep resistance up to 150 ◦ C. The relatively cheap material magnesium becomes very cost-intensive through the use of expensive RE [2]. For these reasons, alternative creep-resistant magnesium alloys have been developed for many years which do not require RE as alloying elements. A development in this area is the DieMag alloy series, such as DieMag422 (Mg-4Al-2Ba-2Ca/ABaX422) They contain barium and calcium as alloying elements [3]
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