Browsing by Author "Donkoh, Ebenezer"

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    Study of the Effects of Ageing Temperature and Ageing Time on the Microstructure and Some Mechanical Properties of Sand Cast AL-SI-CU and AL-SI-MG Alloys
    (SEPTEMBER 2016 ) Donkoh, Ebenezer
    This research work studied the effect of heat treatment on some mechanical properties of locally produced sand cast Al-Si-Mg and Al-Si-Cu alloys. The T6 heat treatment method was used for the heat treatment. The results show that solution heat treatment of Al-14%Si-2.66Cu at 480 oC produced an ultimate tensile strength of (126.72±0.51 MPa) with impact energy of (18.00±0.58 J) and the as-cast ultimate tensile strength was (129.94±0.66 MPa) with impact energy of (13.33±1.15 J). The peak ultimate tensile strength for the Al-14%Si-2.66Cu, artificially aged at 155oC for 7 hours was (143.46±0.33 MPa) with impact energy of (17.33±0.58 J) and (150.70±1.20 MPa) with impact energy of (14.67±1.53 J) when artificially aged at 165 oC for 6 hours. The solution heat treatment of Al-14%Si-0.288Mg at 530 oC for 6 hours resulted in an ultimate tensile strength of (120.00±0.70 MPa) with impact energy of (20.00±2.65 J) and the ascast ultimate tensile strength was (122.00±0.70 MPa) with impact energy of (12.33±0.58 J).The peak ultimate tensile strength was (228.32±0.93 MPa) with impact energy (14.00±0.58 J) when artificially aged at 170 oC for 5 hours. The peak strength at 160 oC for 7 hours was (200.40±0.98 MPa) with impact energy (13.67±0.58 J). These values obtained for the ultimate tensile strength were within the European standards for the ultimate tensile strength of sand cast Al-Si-Mg and Al-Si-Cu alloys (ISO Al Si7Mg, ISO AlSi10Mg and ISO Al Si12Cu in the T6 conditions are 260, 260 and 170 MPa) respectively. Also the Al-Si-Mg alloy responded much better to the heat treatment than the Al-Si-Cu alloy.