Influence of secondary dendrite arm spacing (SDAS) on the fatigue properties of different conventional automotive aluminum cast alloys

For industrial in-series castings, the presence of casting defects, like porosity, geometrically complex intermetallic precipitates and the occurrence of eutectic silicon of varying morphologies, is well known but hard to prevent due to technical and economic limitations. To improve the performance...

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Main Authors: Sascha Gerbe, Ulrich Krupp, Wilhelm Michels
Format: Article
Language:English
Published: Gruppo Italiano Frattura 2019-04-01
Series:Fracture and Structural Integrity
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Online Access:https://www.fracturae.com/index.php/fis/article/view/2314/2368
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author Sascha Gerbe
Ulrich Krupp
Wilhelm Michels
author_facet Sascha Gerbe
Ulrich Krupp
Wilhelm Michels
author_sort Sascha Gerbe
collection DOAJ
description For industrial in-series castings, the presence of casting defects, like porosity, geometrically complex intermetallic precipitates and the occurrence of eutectic silicon of varying morphologies, is well known but hard to prevent due to technical and economic limitations. To improve the performance and safety of cast aluminum products, the present work deals with the correlation between the cooling-rate-dependent secondary dendrite arm spacing (SDAS), the high- and very-high-cycle-fatigue (VHCF) behavior, the crack propagation mechanisms under pure bending with a focus on the crack propagation paths for near-threshold stress intensity factor ranges ?KI using two conventional automotive cast aluminum alloys AlSi8Cu3 (engine blocks) and AlSi7Cu0.5Mg (cylinder heads). Furthermore, the role of a variation in porosity on the crack initiation process is discussed. Specimens were extracted from in-series castings choosing positions with a maximal difference in cooling rate and SDAS, respectively. It is shown that porosity is highly influencing the crack initiation mechanism and that the SDAS has a strong influence on both, crack propagation rate and crack propagation paths. Hence, analogies between the SDAS and the grain size as influence factor according to the Hall-Petch relationship were identified.
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series Fracture and Structural Integrity
spelling doaj-art-f7e5cfd5ab2b4e25a4b99ed28dbef3072025-01-02T23:01:19ZengGruppo Italiano FratturaFracture and Structural Integrity1971-89932019-04-01134810511510.3221/IGF-ESIS.48.1310.3221/IGF-ESIS.48.13Influence of secondary dendrite arm spacing (SDAS) on the fatigue properties of different conventional automotive aluminum cast alloysSascha GerbeUlrich KruppWilhelm MichelsFor industrial in-series castings, the presence of casting defects, like porosity, geometrically complex intermetallic precipitates and the occurrence of eutectic silicon of varying morphologies, is well known but hard to prevent due to technical and economic limitations. To improve the performance and safety of cast aluminum products, the present work deals with the correlation between the cooling-rate-dependent secondary dendrite arm spacing (SDAS), the high- and very-high-cycle-fatigue (VHCF) behavior, the crack propagation mechanisms under pure bending with a focus on the crack propagation paths for near-threshold stress intensity factor ranges ?KI using two conventional automotive cast aluminum alloys AlSi8Cu3 (engine blocks) and AlSi7Cu0.5Mg (cylinder heads). Furthermore, the role of a variation in porosity on the crack initiation process is discussed. Specimens were extracted from in-series castings choosing positions with a maximal difference in cooling rate and SDAS, respectively. It is shown that porosity is highly influencing the crack initiation mechanism and that the SDAS has a strong influence on both, crack propagation rate and crack propagation paths. Hence, analogies between the SDAS and the grain size as influence factor according to the Hall-Petch relationship were identified.https://www.fracturae.com/index.php/fis/article/view/2314/2368CastAluminumSDASThresholdKitagawa-Takahashi-diagramHall-Petch relationship
spellingShingle Sascha Gerbe
Ulrich Krupp
Wilhelm Michels
Influence of secondary dendrite arm spacing (SDAS) on the fatigue properties of different conventional automotive aluminum cast alloys
Fracture and Structural Integrity
Cast
Aluminum
SDAS
Threshold
Kitagawa-Takahashi-diagram
Hall-Petch relationship
title Influence of secondary dendrite arm spacing (SDAS) on the fatigue properties of different conventional automotive aluminum cast alloys
title_full Influence of secondary dendrite arm spacing (SDAS) on the fatigue properties of different conventional automotive aluminum cast alloys
title_fullStr Influence of secondary dendrite arm spacing (SDAS) on the fatigue properties of different conventional automotive aluminum cast alloys
title_full_unstemmed Influence of secondary dendrite arm spacing (SDAS) on the fatigue properties of different conventional automotive aluminum cast alloys
title_short Influence of secondary dendrite arm spacing (SDAS) on the fatigue properties of different conventional automotive aluminum cast alloys
title_sort influence of secondary dendrite arm spacing sdas on the fatigue properties of different conventional automotive aluminum cast alloys
topic Cast
Aluminum
SDAS
Threshold
Kitagawa-Takahashi-diagram
Hall-Petch relationship
url https://www.fracturae.com/index.php/fis/article/view/2314/2368
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AT ulrichkrupp influenceofsecondarydendritearmspacingsdasonthefatiguepropertiesofdifferentconventionalautomotivealuminumcastalloys
AT wilhelmmichels influenceofsecondarydendritearmspacingsdasonthefatiguepropertiesofdifferentconventionalautomotivealuminumcastalloys