| 1. |
- Tiryakioğlu, M., et al.
(författare)
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The Impact of the Minimum Ductility Requirement in Automotive Castings on the Carbon Dioxide Footprint throughout the Useful Life of an Electric Car
- 2023
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Ingår i: Metals. - : MDPI. - 2075-4701. ; 13:3
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Tidskriftsartikel (refereegranskat)abstract
- There is a trend in the automotive producers to require that foundries use more secondary aluminum alloy ingots to reduce the CO2 footprint of car production. The merits of this trend have been investigated in this study. Results have shown that requiring the use of more secondary ingots while simultaneously reducing the elongation requirement of aluminum alloy die castings is counterproductive, i.e., increases the CO2 footprint of the car over its useful life by not taking advantage of the weight reduction possible. It is recommended that (i) foundries improve their melt handling capabilities to reduce and minimize the entrainment damage made to the melt in the melting and casting process chain, and (ii) automobile producers reduce the weight of die castings by increasing requirements on elongation, to secure a reduced CO2-footprint in the designs, materials usage and life-cycle of cars.
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| 2. |
- Bogdanoff, Toni, et al.
(författare)
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On the combined effects of surface quality and pore size on the fatigue life of Al–7Si–3Cu–Mg alloy castings
- 2023
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Ingår i: Materials Science & Engineering. - : Elsevier. - 0921-5093 .- 1873-4936. ; 885
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Tidskriftsartikel (refereegranskat)abstract
- This study has aimed to determine the effects of surface quality and pore size, obtained by different levels of hydrogen content of the liquid metal, on the fatigue behavior of an Al–7%Si–3%Cu–Mg casting alloy. Three surface conditions have been studied: as-cast rough, as-cast smooth, and standard machined and polished surface. The S–N curves have shown that surface roughness and hydrogen content individually impact fatigue strength. Surprisingly, the fatigue strength of machined and polished samples, which aligns with standard testing practices, is significantly reduced, compared to other conditions. Fatigue cracks have been observed to initiate at the pores just below the as-cast surface or on the machined surfaces. In all cases, pores have been observed to be surrounded by bifilms. Moreover, hydrogen content and roughness of the as-cast surface have been found to interact to determine the fatigue performance. These findings necessitate a re-evaluation of fatigue testing procedures for cast aluminum components.
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| 3. |
- Bogdanoff, Toni, et al.
(författare)
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On the secondary cracks during crack propagation in an Al-Si-Cu-Mg alloy : An in-situ study
- 2023
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Ingår i: Materials Characterization. - : Elsevier. - 1044-5803 .- 1873-4189. ; 203
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Tidskriftsartikel (refereegranskat)abstract
- During in situ cyclic testing of hot isostatically pressed and heat-treated Al-5Si-0.5 Mg-1Cu alloy castings, cracks were observed to open up in places far away from the area of stress concentration. Cyclic testing was interrupted to assess these cracks. Analysis showed that these cracks originated from oxide bifilms that were entrained in the liquid state. Moreover, Si and Fe-rich intermetallics were observed to have precipitated on these bifilms. These finding makes it necessary to re-evaluate how damage is interpreted in mechanical studies. Entrainment damage, which takes place in the liquid state, may remain invisible in non-destructive inspection and can significantly affect fatigue properties when bifilms open up under low tensile stresses and present the propagating crack a path of low resistance during propagation.
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