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Bernhard Stauder - One of the best experts on this subject based on the ideXlab platform.
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thermo mechanical fatigue influence of copper and silicon on hypo eutectic al si cu and al si mg cast alloys used in Cylinder Heads
International Journal of Fatigue, 2016Co-Authors: Patrik Huter, Stefan Oberfrank, Florian Grun, Bernhard StauderAbstract:Abstract In this paper, different hypo-eutectic Al–Si cast alloys with varying silicon, copper and iron contents were tested under thermo-mechanical fatigue (TMF) conditions to achieve a unified approach to damaging and fatigue endurance behaviour. The Cylinder Heads from which the specimens were taken were serially produced with T79 heat treatment. This includes homogenisation, quenching and ageing. The alloy used by these investigations are commonly used for automotive Cylinder Heads. Under operational conditions, a complex interaction of mechanical and thermal cyclic loadings is inherent. Hence, the main purpose here is to distinguish between the influences of the alloying elements of hypo-eutectic Al–Si cast alloys and propose its effects to mechanical and environmental damages. The results underlined the important role of hard phases for crack nucleation especially in high copper alloys. The hard phases, like eutectic silicon or primary AlCu, AlFeSi phases in general got ruptured, independent of the applied mechanical loading. In contrast, damages in low copper alloys were caused by high plastic matrix deformations and the loss of adhesion of eutectic silicon particles. For both types of alloys, the crack propagation was mostly constrained on the eutectic itself. An improved TMF endurance was achieved by AlSi9Cu1(Sr) and primary AlSi8Cu3. Here, probably the increased matrix strength by precipitation hardening and the manifold crack deflections on the eutectic silicon reduced intrinsically the microstructural damage. Further, in TMF regimes it is recommended to use Al–Si cast alloys with low iron contents because present ternary α- Al 15 ( Fe,Mn ) 3 Si 2 and quaternary β- Al 5 FeSi supported crack nucleation and lowered the fatigue endurance. Additionally, an over-aged AlSi7MgCu alloy in T74 condition significantly lacks in fatigue endurance because of a minor fatigue strength by incoherent θ-precipitations. However, the results presented here identify the major damages of hypo-eutectic Al–Si cast alloys and the influences of the alloying elements on TMF endurance. This enables further unified fatigue modelling by the automotive designer and additional optimizations of the metallurgical systems by the foundry which underlines the demand of improved knowledge of the Cylinder head under real-life operational conditions.
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high and low cycle fatigue influence of silicon copper strontium and iron on hypo eutectic al si cu and al si mg cast alloys used in Cylinder Heads
International Journal of Fatigue, 2016Co-Authors: Patrik Huter, Stefan Oberfrank, Florian Grun, Philipp Renhart, Martin Schwab, Bernhard StauderAbstract:Abstract In this publication, ambient condition fatigue investigations with different types of Al–Si–Cu and Al–Si–Mg cast alloys in rotating-bending high-cycle fatigue (HCF) and push–pull low-cycle fatigue (LCF) regimes have been performed with varying Si, Cu, Fe and Sr contents. The cast alloys investigated here are common used in Cylinder Heads for automotive application. Because the Cylinder head is one of the most fatigued parts in combustion chamber engines, the microstructural knowledge of the damage process provides a tool of construction and its material selection. The investigations were also supported with an in-situ microstructural crack observation in high plasticity rotating-bending regimes. The specimens were directly processed out of serial produced T79 heat-treated Cylinder Heads to provide the equal microstructure for testing as under operational conditions. The observations clearly identified the effects of the individual alloying elements both under low- and high-cycle fatigue. The crack propagation speed and the crack paths were majorly influenced by the eutectic silicon. Additional, the precipitation hardening due to copper affected significantly the fatigue endurance, too. In high plasticities the silicon’s influence got almost lost and only the matrix strength was crucial. Thus, increased fatigue strength in high loaded LCF regimes was observed for alloys with less copper content, thus higher ductility. By contrast, improved HCF and low loaded LCF endurance was only achieved when the matrix strength was increased by copper’s precipitation hardening. Crack branching and deflections strongly influenced the microstructural damage of the ductile AlSi7Mg(Sr) and hence, gained its fatigue strength. Iron phases could not identified as harmful inclusions, since the phases were similar in size of other hard phase elements like the other primary intermetallic phases like Al 2 Cu and β- Si phases under notch stress aspects, by the well defined solidification process in the test section. Because the crack nucleation mainly occurred on Si particles, strontium as a refinement agent influenced the early crack onset and accordingly the fatigue in total. Thus, the AlSi6Cu4(Sr) had increased lifetimes compared to AlSi6Cu4 both in HCF and LCF. Further, the presented results provide a modification of the Manson–Coffin approach to describe the relationship between plastic strain and lifetime, valid for all proposed alloys with only one set of parameters. Thus, it was possible to perform the fatigue calculation with a reduced range of scatter.
Patrik Huter - One of the best experts on this subject based on the ideXlab platform.
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thermo mechanical fatigue influence of copper and silicon on hypo eutectic al si cu and al si mg cast alloys used in Cylinder Heads
International Journal of Fatigue, 2016Co-Authors: Patrik Huter, Stefan Oberfrank, Florian Grun, Bernhard StauderAbstract:Abstract In this paper, different hypo-eutectic Al–Si cast alloys with varying silicon, copper and iron contents were tested under thermo-mechanical fatigue (TMF) conditions to achieve a unified approach to damaging and fatigue endurance behaviour. The Cylinder Heads from which the specimens were taken were serially produced with T79 heat treatment. This includes homogenisation, quenching and ageing. The alloy used by these investigations are commonly used for automotive Cylinder Heads. Under operational conditions, a complex interaction of mechanical and thermal cyclic loadings is inherent. Hence, the main purpose here is to distinguish between the influences of the alloying elements of hypo-eutectic Al–Si cast alloys and propose its effects to mechanical and environmental damages. The results underlined the important role of hard phases for crack nucleation especially in high copper alloys. The hard phases, like eutectic silicon or primary AlCu, AlFeSi phases in general got ruptured, independent of the applied mechanical loading. In contrast, damages in low copper alloys were caused by high plastic matrix deformations and the loss of adhesion of eutectic silicon particles. For both types of alloys, the crack propagation was mostly constrained on the eutectic itself. An improved TMF endurance was achieved by AlSi9Cu1(Sr) and primary AlSi8Cu3. Here, probably the increased matrix strength by precipitation hardening and the manifold crack deflections on the eutectic silicon reduced intrinsically the microstructural damage. Further, in TMF regimes it is recommended to use Al–Si cast alloys with low iron contents because present ternary α- Al 15 ( Fe,Mn ) 3 Si 2 and quaternary β- Al 5 FeSi supported crack nucleation and lowered the fatigue endurance. Additionally, an over-aged AlSi7MgCu alloy in T74 condition significantly lacks in fatigue endurance because of a minor fatigue strength by incoherent θ-precipitations. However, the results presented here identify the major damages of hypo-eutectic Al–Si cast alloys and the influences of the alloying elements on TMF endurance. This enables further unified fatigue modelling by the automotive designer and additional optimizations of the metallurgical systems by the foundry which underlines the demand of improved knowledge of the Cylinder head under real-life operational conditions.
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high and low cycle fatigue influence of silicon copper strontium and iron on hypo eutectic al si cu and al si mg cast alloys used in Cylinder Heads
International Journal of Fatigue, 2016Co-Authors: Patrik Huter, Stefan Oberfrank, Florian Grun, Philipp Renhart, Martin Schwab, Bernhard StauderAbstract:Abstract In this publication, ambient condition fatigue investigations with different types of Al–Si–Cu and Al–Si–Mg cast alloys in rotating-bending high-cycle fatigue (HCF) and push–pull low-cycle fatigue (LCF) regimes have been performed with varying Si, Cu, Fe and Sr contents. The cast alloys investigated here are common used in Cylinder Heads for automotive application. Because the Cylinder head is one of the most fatigued parts in combustion chamber engines, the microstructural knowledge of the damage process provides a tool of construction and its material selection. The investigations were also supported with an in-situ microstructural crack observation in high plasticity rotating-bending regimes. The specimens were directly processed out of serial produced T79 heat-treated Cylinder Heads to provide the equal microstructure for testing as under operational conditions. The observations clearly identified the effects of the individual alloying elements both under low- and high-cycle fatigue. The crack propagation speed and the crack paths were majorly influenced by the eutectic silicon. Additional, the precipitation hardening due to copper affected significantly the fatigue endurance, too. In high plasticities the silicon’s influence got almost lost and only the matrix strength was crucial. Thus, increased fatigue strength in high loaded LCF regimes was observed for alloys with less copper content, thus higher ductility. By contrast, improved HCF and low loaded LCF endurance was only achieved when the matrix strength was increased by copper’s precipitation hardening. Crack branching and deflections strongly influenced the microstructural damage of the ductile AlSi7Mg(Sr) and hence, gained its fatigue strength. Iron phases could not identified as harmful inclusions, since the phases were similar in size of other hard phase elements like the other primary intermetallic phases like Al 2 Cu and β- Si phases under notch stress aspects, by the well defined solidification process in the test section. Because the crack nucleation mainly occurred on Si particles, strontium as a refinement agent influenced the early crack onset and accordingly the fatigue in total. Thus, the AlSi6Cu4(Sr) had increased lifetimes compared to AlSi6Cu4 both in HCF and LCF. Further, the presented results provide a modification of the Manson–Coffin approach to describe the relationship between plastic strain and lifetime, valid for all proposed alloys with only one set of parameters. Thus, it was possible to perform the fatigue calculation with a reduced range of scatter.
Stefan Oberfrank - One of the best experts on this subject based on the ideXlab platform.
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thermo mechanical fatigue influence of copper and silicon on hypo eutectic al si cu and al si mg cast alloys used in Cylinder Heads
International Journal of Fatigue, 2016Co-Authors: Patrik Huter, Stefan Oberfrank, Florian Grun, Bernhard StauderAbstract:Abstract In this paper, different hypo-eutectic Al–Si cast alloys with varying silicon, copper and iron contents were tested under thermo-mechanical fatigue (TMF) conditions to achieve a unified approach to damaging and fatigue endurance behaviour. The Cylinder Heads from which the specimens were taken were serially produced with T79 heat treatment. This includes homogenisation, quenching and ageing. The alloy used by these investigations are commonly used for automotive Cylinder Heads. Under operational conditions, a complex interaction of mechanical and thermal cyclic loadings is inherent. Hence, the main purpose here is to distinguish between the influences of the alloying elements of hypo-eutectic Al–Si cast alloys and propose its effects to mechanical and environmental damages. The results underlined the important role of hard phases for crack nucleation especially in high copper alloys. The hard phases, like eutectic silicon or primary AlCu, AlFeSi phases in general got ruptured, independent of the applied mechanical loading. In contrast, damages in low copper alloys were caused by high plastic matrix deformations and the loss of adhesion of eutectic silicon particles. For both types of alloys, the crack propagation was mostly constrained on the eutectic itself. An improved TMF endurance was achieved by AlSi9Cu1(Sr) and primary AlSi8Cu3. Here, probably the increased matrix strength by precipitation hardening and the manifold crack deflections on the eutectic silicon reduced intrinsically the microstructural damage. Further, in TMF regimes it is recommended to use Al–Si cast alloys with low iron contents because present ternary α- Al 15 ( Fe,Mn ) 3 Si 2 and quaternary β- Al 5 FeSi supported crack nucleation and lowered the fatigue endurance. Additionally, an over-aged AlSi7MgCu alloy in T74 condition significantly lacks in fatigue endurance because of a minor fatigue strength by incoherent θ-precipitations. However, the results presented here identify the major damages of hypo-eutectic Al–Si cast alloys and the influences of the alloying elements on TMF endurance. This enables further unified fatigue modelling by the automotive designer and additional optimizations of the metallurgical systems by the foundry which underlines the demand of improved knowledge of the Cylinder head under real-life operational conditions.
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high and low cycle fatigue influence of silicon copper strontium and iron on hypo eutectic al si cu and al si mg cast alloys used in Cylinder Heads
International Journal of Fatigue, 2016Co-Authors: Patrik Huter, Stefan Oberfrank, Florian Grun, Philipp Renhart, Martin Schwab, Bernhard StauderAbstract:Abstract In this publication, ambient condition fatigue investigations with different types of Al–Si–Cu and Al–Si–Mg cast alloys in rotating-bending high-cycle fatigue (HCF) and push–pull low-cycle fatigue (LCF) regimes have been performed with varying Si, Cu, Fe and Sr contents. The cast alloys investigated here are common used in Cylinder Heads for automotive application. Because the Cylinder head is one of the most fatigued parts in combustion chamber engines, the microstructural knowledge of the damage process provides a tool of construction and its material selection. The investigations were also supported with an in-situ microstructural crack observation in high plasticity rotating-bending regimes. The specimens were directly processed out of serial produced T79 heat-treated Cylinder Heads to provide the equal microstructure for testing as under operational conditions. The observations clearly identified the effects of the individual alloying elements both under low- and high-cycle fatigue. The crack propagation speed and the crack paths were majorly influenced by the eutectic silicon. Additional, the precipitation hardening due to copper affected significantly the fatigue endurance, too. In high plasticities the silicon’s influence got almost lost and only the matrix strength was crucial. Thus, increased fatigue strength in high loaded LCF regimes was observed for alloys with less copper content, thus higher ductility. By contrast, improved HCF and low loaded LCF endurance was only achieved when the matrix strength was increased by copper’s precipitation hardening. Crack branching and deflections strongly influenced the microstructural damage of the ductile AlSi7Mg(Sr) and hence, gained its fatigue strength. Iron phases could not identified as harmful inclusions, since the phases were similar in size of other hard phase elements like the other primary intermetallic phases like Al 2 Cu and β- Si phases under notch stress aspects, by the well defined solidification process in the test section. Because the crack nucleation mainly occurred on Si particles, strontium as a refinement agent influenced the early crack onset and accordingly the fatigue in total. Thus, the AlSi6Cu4(Sr) had increased lifetimes compared to AlSi6Cu4 both in HCF and LCF. Further, the presented results provide a modification of the Manson–Coffin approach to describe the relationship between plastic strain and lifetime, valid for all proposed alloys with only one set of parameters. Thus, it was possible to perform the fatigue calculation with a reduced range of scatter.
Florian Grun - One of the best experts on this subject based on the ideXlab platform.
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thermo mechanical fatigue influence of copper and silicon on hypo eutectic al si cu and al si mg cast alloys used in Cylinder Heads
International Journal of Fatigue, 2016Co-Authors: Patrik Huter, Stefan Oberfrank, Florian Grun, Bernhard StauderAbstract:Abstract In this paper, different hypo-eutectic Al–Si cast alloys with varying silicon, copper and iron contents were tested under thermo-mechanical fatigue (TMF) conditions to achieve a unified approach to damaging and fatigue endurance behaviour. The Cylinder Heads from which the specimens were taken were serially produced with T79 heat treatment. This includes homogenisation, quenching and ageing. The alloy used by these investigations are commonly used for automotive Cylinder Heads. Under operational conditions, a complex interaction of mechanical and thermal cyclic loadings is inherent. Hence, the main purpose here is to distinguish between the influences of the alloying elements of hypo-eutectic Al–Si cast alloys and propose its effects to mechanical and environmental damages. The results underlined the important role of hard phases for crack nucleation especially in high copper alloys. The hard phases, like eutectic silicon or primary AlCu, AlFeSi phases in general got ruptured, independent of the applied mechanical loading. In contrast, damages in low copper alloys were caused by high plastic matrix deformations and the loss of adhesion of eutectic silicon particles. For both types of alloys, the crack propagation was mostly constrained on the eutectic itself. An improved TMF endurance was achieved by AlSi9Cu1(Sr) and primary AlSi8Cu3. Here, probably the increased matrix strength by precipitation hardening and the manifold crack deflections on the eutectic silicon reduced intrinsically the microstructural damage. Further, in TMF regimes it is recommended to use Al–Si cast alloys with low iron contents because present ternary α- Al 15 ( Fe,Mn ) 3 Si 2 and quaternary β- Al 5 FeSi supported crack nucleation and lowered the fatigue endurance. Additionally, an over-aged AlSi7MgCu alloy in T74 condition significantly lacks in fatigue endurance because of a minor fatigue strength by incoherent θ-precipitations. However, the results presented here identify the major damages of hypo-eutectic Al–Si cast alloys and the influences of the alloying elements on TMF endurance. This enables further unified fatigue modelling by the automotive designer and additional optimizations of the metallurgical systems by the foundry which underlines the demand of improved knowledge of the Cylinder head under real-life operational conditions.
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high and low cycle fatigue influence of silicon copper strontium and iron on hypo eutectic al si cu and al si mg cast alloys used in Cylinder Heads
International Journal of Fatigue, 2016Co-Authors: Patrik Huter, Stefan Oberfrank, Florian Grun, Philipp Renhart, Martin Schwab, Bernhard StauderAbstract:Abstract In this publication, ambient condition fatigue investigations with different types of Al–Si–Cu and Al–Si–Mg cast alloys in rotating-bending high-cycle fatigue (HCF) and push–pull low-cycle fatigue (LCF) regimes have been performed with varying Si, Cu, Fe and Sr contents. The cast alloys investigated here are common used in Cylinder Heads for automotive application. Because the Cylinder head is one of the most fatigued parts in combustion chamber engines, the microstructural knowledge of the damage process provides a tool of construction and its material selection. The investigations were also supported with an in-situ microstructural crack observation in high plasticity rotating-bending regimes. The specimens were directly processed out of serial produced T79 heat-treated Cylinder Heads to provide the equal microstructure for testing as under operational conditions. The observations clearly identified the effects of the individual alloying elements both under low- and high-cycle fatigue. The crack propagation speed and the crack paths were majorly influenced by the eutectic silicon. Additional, the precipitation hardening due to copper affected significantly the fatigue endurance, too. In high plasticities the silicon’s influence got almost lost and only the matrix strength was crucial. Thus, increased fatigue strength in high loaded LCF regimes was observed for alloys with less copper content, thus higher ductility. By contrast, improved HCF and low loaded LCF endurance was only achieved when the matrix strength was increased by copper’s precipitation hardening. Crack branching and deflections strongly influenced the microstructural damage of the ductile AlSi7Mg(Sr) and hence, gained its fatigue strength. Iron phases could not identified as harmful inclusions, since the phases were similar in size of other hard phase elements like the other primary intermetallic phases like Al 2 Cu and β- Si phases under notch stress aspects, by the well defined solidification process in the test section. Because the crack nucleation mainly occurred on Si particles, strontium as a refinement agent influenced the early crack onset and accordingly the fatigue in total. Thus, the AlSi6Cu4(Sr) had increased lifetimes compared to AlSi6Cu4 both in HCF and LCF. Further, the presented results provide a modification of the Manson–Coffin approach to describe the relationship between plastic strain and lifetime, valid for all proposed alloys with only one set of parameters. Thus, it was possible to perform the fatigue calculation with a reduced range of scatter.
Mohammad Azadi - One of the best experts on this subject based on the ideXlab platform.
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numerical simulations of cyclic behaviors in light alloys under isothermal and thermo mechanical fatigue loadings
Materials & Design, 2014Co-Authors: Gholam Hossein Farrahi, M Felfeli, Amir Shamloo, Mohammad AzadiAbstract:Abstract In this article, numerical simulations of cyclic behaviors in light alloys are conducted under isothermal and thermo-mechanical fatigue loadings. For this purpose, an aluminum alloy (A356) which is widely used in Cylinder Heads and a magnesium alloy (AZ91) which can be applicable in Cylinder Heads are considered to study their stress–strain hysteresis loops. Two plasticity approaches including the Chaboche’s hardening model and the Nagode’s spring-slider model are applied to simulate cyclic behaviors. To validate obtained results, strain-controlled fatigue tests are performed under low cycle and thermo-mechanical fatigue loadings. Numerical results demonstrate a good agreement with experimental data at the mid-life cycle of fatigue tests in light alloys. Calibrated material constants based on low cycle fatigue tests at various temperatures are applied to models to estimate the thermo-mechanical behavior of light alloys. The reason is to reduce costs and the testing time by performing isothermal fatigue experiments at higher strain rates.
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a new energy based isothermal and thermo mechanical fatigue lifetime prediction model for aluminium silicon magnesium alloy
Fatigue & Fracture of Engineering Materials & Structures, 2013Co-Authors: Gholam Hossein Farrahi, Mohammad Azadi, Gerhard Winter, Wilfried EichlsederAbstract:In this paper, a new fatigue lifetime prediction model is presented for the aluminium–silicon–magnesium alloy, A356.0. This model is based on the plastic strain energy density per cycle including two correction factors in order to consider the effect of the mean stress and the maximum temperature. The thermal term considers creep and oxidation damages in A356.0 alloy. To calibrate the model, isothermal fatigue and out-of-phase thermo-mechanical fatigue (TMF) tests were conducted on the A356.0 alloy. Results showed an improvement in predicting fatigue lifetimes by the present model in comparison with classical theories and also the plastic strain energy density (without any correction factors). Therefore, this model is applicable for TMF, low cycle fatigue (LCF) and both TMF/LCF lifetimes of the A356.0 alloy. Furthermore, this model can be easily used for the estimation of thermo-mechanical conditions in components such as Cylinder Heads.
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Heat treatment effect on thermo-mechanical fatigue and low cycle fatigue behaviors of A356.0 aluminum alloy
Materials & Design, 2013Co-Authors: Mohammad Azadi, Mehdi Mokhtari ShirazabadAbstract:In the present paper, the heat treatment effect on A356.0, a cast aluminum alloy which has been widely used in diesel engine Cylinder Heads, is investigated under out-of-phase thermo-mechanical fatigue and low cycle fatigue (at different temperatures) loadings. A typical heat treatment is applied to the material including 8h solution at 535°C, water quench and 3h ageing at 180°C. The experimental fatigue results show that the heat treatment process has considerable influence on mechanical and low cycle fatigue behaviors, especially at room temperature, but its effect on thermo-mechanical fatigue lifetime is not significant. The improvement in the strength can be explained by the dislocation theory. Under thermo-mechanical fatigue loadings, the difference between the fatigue lifetime of A356.0 alloy and A356.0-T6 alloy decreases when the temperature range increases. In this condition, plastic strain increases severely during the fatigue cycles in A356.0-T6 alloy due to over-ageing phenomenon and therefore, the amount of cyclic softening in heat treated alloy is more.
