Saad Ahmed - Academia.edu (original) (raw)
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University for Development Studies, Tamale, Ghana
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Papers by Saad Ahmed
Materials Science and Engineering: B, 2008
The present study focuses on the microstructure and mechanical properties of dissimilar joints of... more The present study focuses on the microstructure and mechanical properties of dissimilar joints of 2024-T3 Al alloy to 7075-T6 Al alloy produced by friction stir welding. Effects of welding speed and fixed location of base metals on microstructures, hardness distributions, and tensile properties of the welded joints were investigated. SEM-EDS analysis revealed that the stir zone contains a mixed structure and onion ring pattern with a periodic change of grain size as well as a heterogeneous distribution of alloying elements. The maximum tensile strength of 423.0 MPa was achieved for the joint produced at welding speed of 1.67 mm/s when 2024 Al alloy was located on the advancing side.
MATERIALS TRANSACTIONS, 2007
Dissimilar alloys such as 2024-T3 Al alloy and AZ31 Mg alloy of plates in 3 mm thickness has been... more Dissimilar alloys such as 2024-T3 Al alloy and AZ31 Mg alloy of plates in 3 mm thickness has been friction stir butt welded. The welding was carried out at a constant rotation speed of 2500 min À1 and welding speeds of 200, 300, 400 and 550 mm/min. Effects of welding speeds on microstructures and hardness distributions of the joints were investigated. Distribution of phases in the stir zone (SZ) was analyzed by a scanning electron microscope (SEM) equipped with an energy dispersive X-ray spectroscopy (EDS). Increasing welding speed brought about a redistribution of phases in SZ where the regions occupied by 2024 Al alloy concentrated in the lower portion of SZ while AZ31 Mg alloy concentrated in the upper region beneath the tool shoulder. The laminated structure was formed in the SZ near the boundary between SZ and TMAZ on the advancing side of 2024 Al alloy regardless of the welding speed. The hardness value fluctuates in the SZ due to formation of intermetallic compounds that formed by constitutional liquation during welding.
Materials Science and Engineering: A, 2007
Friction stir welding (FSW) has received a great deal of attention as a new solid-state welding t... more Friction stir welding (FSW) has received a great deal of attention as a new solid-state welding technique. In the present study, the relationship between the microstructure of stir zone and the mechanical property of FS-welded 5083 aluminum alloy was investigated. The microstructures of the stir zones consisted of fine equiaxed grains at various FSW conditions in FS-welded 5083 Al alloy.
AA 2024-T3 Aluminum alloy plates of 3 mm thickness were friction stir butt welded at a constant r... more AA 2024-T3 Aluminum alloy plates of 3 mm thickness were friction stir butt welded at a constant rotation speed of 1250 min À1 and welding speeds of 50 and 100 mm/min. Three types of backing materials such as SUS304, pure copper block, and a combination of copper-block with 0.5 mm SUS304 were used. Controls of temperature history were achieved and their effects on microstructures, hardness distributions, and tensile properties of the joints were investigated. Grain size of the stir zone decreased from 7.4 mm in the case of stainless steel to 4.4 and 1.7 mm for the cases of a combination backing type and copper-block respectively. As a result of higher heating/or cooling rates, both higher welding speed and copper-block backing material resulted in increased hardness in HAZ and a maximum value was achieved for the combined backing plate at 100 mm/min of welding speed. Higher peak temperature was beneficial for higher hardness in stir zone while lower one in HAZ. A maximum tensile stre...
Materials Science and Engineering: B, 2008
The present study focuses on the microstructure and mechanical properties of dissimilar joints of... more The present study focuses on the microstructure and mechanical properties of dissimilar joints of 2024-T3 Al alloy to 7075-T6 Al alloy produced by friction stir welding. Effects of welding speed and fixed location of base metals on microstructures, hardness distributions, and tensile properties of the welded joints were investigated. SEM-EDS analysis revealed that the stir zone contains a mixed structure and onion ring pattern with a periodic change of grain size as well as a heterogeneous distribution of alloying elements. The maximum tensile strength of 423.0 MPa was achieved for the joint produced at welding speed of 1.67 mm/s when 2024 Al alloy was located on the advancing side.
MATERIALS TRANSACTIONS, 2007
Dissimilar alloys such as 2024-T3 Al alloy and AZ31 Mg alloy of plates in 3 mm thickness has been... more Dissimilar alloys such as 2024-T3 Al alloy and AZ31 Mg alloy of plates in 3 mm thickness has been friction stir butt welded. The welding was carried out at a constant rotation speed of 2500 min À1 and welding speeds of 200, 300, 400 and 550 mm/min. Effects of welding speeds on microstructures and hardness distributions of the joints were investigated. Distribution of phases in the stir zone (SZ) was analyzed by a scanning electron microscope (SEM) equipped with an energy dispersive X-ray spectroscopy (EDS). Increasing welding speed brought about a redistribution of phases in SZ where the regions occupied by 2024 Al alloy concentrated in the lower portion of SZ while AZ31 Mg alloy concentrated in the upper region beneath the tool shoulder. The laminated structure was formed in the SZ near the boundary between SZ and TMAZ on the advancing side of 2024 Al alloy regardless of the welding speed. The hardness value fluctuates in the SZ due to formation of intermetallic compounds that formed by constitutional liquation during welding.
Materials Science and Engineering: A, 2007
Friction stir welding (FSW) has received a great deal of attention as a new solid-state welding t... more Friction stir welding (FSW) has received a great deal of attention as a new solid-state welding technique. In the present study, the relationship between the microstructure of stir zone and the mechanical property of FS-welded 5083 aluminum alloy was investigated. The microstructures of the stir zones consisted of fine equiaxed grains at various FSW conditions in FS-welded 5083 Al alloy.
AA 2024-T3 Aluminum alloy plates of 3 mm thickness were friction stir butt welded at a constant r... more AA 2024-T3 Aluminum alloy plates of 3 mm thickness were friction stir butt welded at a constant rotation speed of 1250 min À1 and welding speeds of 50 and 100 mm/min. Three types of backing materials such as SUS304, pure copper block, and a combination of copper-block with 0.5 mm SUS304 were used. Controls of temperature history were achieved and their effects on microstructures, hardness distributions, and tensile properties of the joints were investigated. Grain size of the stir zone decreased from 7.4 mm in the case of stainless steel to 4.4 and 1.7 mm for the cases of a combination backing type and copper-block respectively. As a result of higher heating/or cooling rates, both higher welding speed and copper-block backing material resulted in increased hardness in HAZ and a maximum value was achieved for the combined backing plate at 100 mm/min of welding speed. Higher peak temperature was beneficial for higher hardness in stir zone while lower one in HAZ. A maximum tensile stre...