Property Variation Within the Thin-Walled Magnesium Alloy Components

Abstract

Utilization of magnesium alloys within the field of vehicle design offers substantial opportunity for mass reduction. This has resulted in a wide range of automotive applications. More recently, the scope of application has been extended to include components that are considered crash critical. However, the magnesium die casting process is widely reported as producing parts that exhibit large local variation in part properties. Hence, this introduces the technical challenge of how to design effectively based upon these constraints. In order to better understand this phenomenon, two large size thin walled production components were examined. Tensile test coupons were extracted from multiple locations. Micro and macro level investigations were also conducted in an effort to identify the root cause of property variation. This paper discusses the influences of porosity on mechanical property variation, specifically tensile strain to failure. Further discussion is also presented, detailing a proposed empirical model, for the prediction of local strain to failure.

Modeling the tensile failure of cast magnesium alloys

“…Numerous researchers have presented both empirical and analytical approaches in attempts to characterize the dependence of local mechanical properties of both aluminum and magnesium die-cast alloys upon porosity [3,4,[7][8][9][10][11][12][13][14][15][16][17][18][19][20]. Several researchers present data which gives a strong correlation between the elongation of die-cast AM50 and AM60 with measured volumetric porosities [3,4,9].…”

“…Several researchers present data which gives a strong correlation between the elongation of die-cast AM50 and AM60 with measured volumetric porosities [3,4,9]. The majority of studies, however [7,8,[10][11][12][13][14][15][16][17][18][19][20], use a measure of the area fraction of porosity, either determined by post-tensile test fractography, or by in situ or non-destructive means, such as X-ray tomography or acoustic emission testing.…”

“…Several researchers have investigated the variations of mechanical properties in cast magnesium alloys, and determined a strong relationship between porosity and the local mechanical properties [3,4,[7][8][9][10][11][12][13][14][15][16][17]. In previous publications [7,8], we have developed an analytical model to predict the tensile elongation of die-cast magnesium alloys from the strain-hardening coefficient of the alloy and the local area fraction and location of porosity.…”

“…With a specific stiffness and strength comparable to steels, magnesium alloys also offer part consolidation and ease of castability. However, the use of die-cast magnesium alloys is currently limited due to the variations of local mechanical properties throughout a complex die-cast component [1][2][3][4]. A major goal in several research programmes in die-cast magnesium alloys is the predictive capability of these local mechanical properties [3][4][5][6].…”

“…However, the use of die-cast magnesium alloys is currently limited due to the variations of local mechanical properties throughout a complex die-cast component [1][2][3][4]. A major goal in several research programmes in die-cast magnesium alloys is the predictive capability of these local mechanical properties [3][4][5][6]. Due to local mechanical property variations, die-casters currently design components using lowerthan-actual properties which results in larger sections, resulting in greater component mass, minimizing the advantages of die-cast magnesium alloys.…”