Junction Characterization in a Functionally Graded Aluminum Part

Abstract

Aluminum alloys are widely used to produce automotive components, thanks to their great mechanical properties–to–density ratio. Engine components such as pistons are conventionally produced by casting of Al–Si eutectic alloys (Silumin alloys) such as EN AC 48000. Due to the harsh working conditions and the lower ductility if compared to aluminum–silicon alloys with lower silicon content, pistons made of this alloy are prone to fatigue failures in the skirt region. In order to overcome such limits, the use of a Functionally Graded Material (FGM) in the production of a piston is proposed. The adoption of a functionally graded architecture can maximize the properties of the component in specific areas. A higher level of thermal resistance in the crown of the piston can be achieved with EN AC 48000 (AlSi12CuNiMg), while higher elongation at rupture in the skirt region would be conferred by an EN AC 42100 (AlSi9Mg0.3). The FGM properties are strictly related to the metallurgical bonding between the alloys as well as to the presence of intermetallic phases in the alloys junction. In the present article, the characterization of gravity casted FGM samples based on Al–Si alloys with respect to microstructure and mechanical testing is presented, with a specific focus on the characterization by impact testing of the joint between the two alloys.

Case Study of the Tensile Fracture Investigation of Additive Manufactured Austenitic Stainless Steels Treated at Cryogenic Conditions

“…Fracture analysis was carried out by field-emission scanning electron microscope (FE-SEM; Zeiss EVO) (Zeiss, Oberkochen, Germany) equipped with energy dispersive X-ray analysis (EDS) (Oxford Instrument, Abingdon-on-Thames, UK). The average size of dimples was evaluated by means of the linear intercept method (according to ASTM E112-96) [26,27]. Different areas were identified as the fracture surface, the sum of which is considered to be representative of the investigated material, by measuring microstructural features on different micrographs.…”

“…Thames, UK). The average size of dimples was evaluated by means of the linear intercept method (according to ASTM E112-96) [26,27]. Different areas were identified as the fracture surface, the sum of which is considered to be representative of the investigated material, by measuring microstructural features on different micrographs.…”

Effects of Casting-Additives on the Microstructure Evolution of Hypoeutectic Aluminium-Silicon Alloys

“…In regard to microstructures, alloy EN AC 45300 belongs to the hypoeutectic system Al-Si and is suitable for both mould and sand castings; its composition contains relatively high amounts of Cu and Mg, enabling the nucleation of intermetallic phases as θ-Al On the contrary, alloy EN AC 43500 can only form intermetallics Fe, Mn, and Mg-based [12,29]. This alloy is largely used for high-pressure die casting but is suitable for all types of casting.…”

“…From this perspective, the usage of different alloys properly joined to each other could be useful to guarantee, for example, a change in specific properties within the piece. Since the various possible welding processes to join aluminium alloys may give rise to weak spots in the joint [10], different kinds of multi-material junctions were proposed [11][12][13][14][15]. On the multi-material solutions are difficult to implement.…”

Design of a Test Rig for the Characterization of Thermal Fatigue and Soldering Resistance of the Surfaces of Tool Steels for High‐Pressure Die‐Casting Dies

“…Complex shapes of casted parts and high production rates often involve difficulties in standardizing casting quality; this is commonly related to the severe thermomechanical loading and the corrosive wear conditions the die is subjected to . Several mechanisms are involved in die wear: metallization due to corrosion of steel by the molten aluminum alloy; washout, a mixed corrosive and erosive mechanism acting when the velocity of the liquid alloy on the die surface exceeds 0.4 m s −1 ; and finally all those mechanisms due to thermal fatigue that create interconnected crack networks . Although these mechanisms are different, they frequently interact with each other.…”