TY - THES

T1 - Temperature and Stress Distribution during Quenching of Al-7Si-0.4Mg

T2 - Simulation and Experimental Verification

AU - Kösemek, Cem

N1 - embargoed until 23-06-2027

PY - 2022

Y1 - 2022

N2 - In the last twenty years, the cast aluminum alloys have been widely used to replace heavy metals. The reason for this was the financial and political pressure to reduce fuel consumption and CO2 emissions. The cast aluminum alloys can be heat treated to obtain better mechanical properties. Therefore, the heat treatment process must be properly performed to develop Al alloys, to obtain longer life, higher ductility and higher strength without changing their chemical composition. It is well-known that residual stresses occur during the heat treatment process (after the quenching) and cause a negative effect on the dimensional stability and fatigue properties subsequently when the heat-treated casting part is in service. In this master thesis, the solution temperature and time were kept unchanged during the heat treatment of aluminium alloys and the quenching process was investigated while ageing has not been applied. Two different immersion directions of quenching were considered. The quenching process was applied to Al-7Si-0.4Mg (wt.%) cast alloy and its effect on the temperature and stress distribution were investigated. The samples were kept in the furnace at 540°C for 6 hours and then quenched in cold water. The quenching process was investigated with the commercial Computational Fluid Dynamics (CFD) simulation software AVL FIRE MTM. It should be noted that the cooling rate during quenching varies depending on the quenching direction. Significant nonuniformity in temperature distribution within the structure was observed, based on the movement of steam bubbles and their effect on heat transfer. On the basis of the temperature distribution, the stresses and deformation within the heat-treated parts were calculated. The obtained simulation results were compared with available measured data on different orientations along the different shaped parts. A good agreement between measured data and simulation results was obtained, which clearly indicates that the real-time quenching process of aluminium alloy with the vapor phase part can be simulated using the commercial CFD code AVL FIRE M™. After the quenching simulation process, solid stress analysis was performed with the AVL FIRE M™ simulation tool and the results were compared with X-ray diffraction (XRD) stress analysis.

AB - In the last twenty years, the cast aluminum alloys have been widely used to replace heavy metals. The reason for this was the financial and political pressure to reduce fuel consumption and CO2 emissions. The cast aluminum alloys can be heat treated to obtain better mechanical properties. Therefore, the heat treatment process must be properly performed to develop Al alloys, to obtain longer life, higher ductility and higher strength without changing their chemical composition. It is well-known that residual stresses occur during the heat treatment process (after the quenching) and cause a negative effect on the dimensional stability and fatigue properties subsequently when the heat-treated casting part is in service. In this master thesis, the solution temperature and time were kept unchanged during the heat treatment of aluminium alloys and the quenching process was investigated while ageing has not been applied. Two different immersion directions of quenching were considered. The quenching process was applied to Al-7Si-0.4Mg (wt.%) cast alloy and its effect on the temperature and stress distribution were investigated. The samples were kept in the furnace at 540°C for 6 hours and then quenched in cold water. The quenching process was investigated with the commercial Computational Fluid Dynamics (CFD) simulation software AVL FIRE MTM. It should be noted that the cooling rate during quenching varies depending on the quenching direction. Significant nonuniformity in temperature distribution within the structure was observed, based on the movement of steam bubbles and their effect on heat transfer. On the basis of the temperature distribution, the stresses and deformation within the heat-treated parts were calculated. The obtained simulation results were compared with available measured data on different orientations along the different shaped parts. A good agreement between measured data and simulation results was obtained, which clearly indicates that the real-time quenching process of aluminium alloy with the vapor phase part can be simulated using the commercial CFD code AVL FIRE M™. After the quenching simulation process, solid stress analysis was performed with the AVL FIRE M™ simulation tool and the results were compared with X-ray diffraction (XRD) stress analysis.

KW - Aluminium-Silizium-Magnesium-Legierung

KW - Abschrecken

KW - Multi-Domain Abschrecken Simulation

KW - Temperaturverteilung

KW - Eigenspannungen

KW - CFD

KW - AVL FIRE M™

KW - XRD.

KW - Aluminium-Silicon-Magnesium alloy

KW - quenching

KW - multi-domain quenching simulation

KW - temperature distribution

KW - residual stresses

KW - CFD

KW - AVL FIRE M™

KW - XRD.

M3 - Master's Thesis

ER -