The Effect of Different Cooling Rates on the Grain Size, Second Phase Morphology, and Wetting Behavior of A205-T7 Heat Treated Aluminum Alloys
Mentor 1
Dr. Pradeep Rohatgi
Location
Union Wisconsin Room
Start Date
28-4-2017 1:30 PM
End Date
28-4-2017 4:00 PM
Description
A205-T7 is an Aluminum-Copper alloy considered to one of the highest strength commercially available alloys for castings. Its castability is comparable to 300-Series Aluminum-Silicon alloys and a unique microstructure that eliminates the shrinkage porosity, hot tearing and stress corrosion cracking that have heretofore inhibited the widespread implementation of investment casting of 200-Series alloys. A205-T7 is being considered for use in products where strength vs. weight ratio is a crucial consideration such as in aerospace and transportation. In the present study, the effect of cooling rates on the grain size, second phase morphology, and static contact angle of A205-T7 aluminum alloy with water has been investigated. To study the effect of cooling rates, a sand casting with varying section thicknesses was made and subjected to T-7 heat treatment (solutionizing and over-aging). Microstructural analysis and water contact angle measurements have been performed on the fully polished specimens using optical microscopy and a goniometer respectively. Furthermore, the effect of droplet size (4 μL to 10 μL) on the wettability of alloys with water was studied. The hardness of the specimens was evaluated using micro hardness measurements. The results show that by increasing the casting thickness, the average grain size increased from 27 μm to 75 μm and the static contact angle was decreased from 76 to 70 degrees.
The Effect of Different Cooling Rates on the Grain Size, Second Phase Morphology, and Wetting Behavior of A205-T7 Heat Treated Aluminum Alloys
Union Wisconsin Room
A205-T7 is an Aluminum-Copper alloy considered to one of the highest strength commercially available alloys for castings. Its castability is comparable to 300-Series Aluminum-Silicon alloys and a unique microstructure that eliminates the shrinkage porosity, hot tearing and stress corrosion cracking that have heretofore inhibited the widespread implementation of investment casting of 200-Series alloys. A205-T7 is being considered for use in products where strength vs. weight ratio is a crucial consideration such as in aerospace and transportation. In the present study, the effect of cooling rates on the grain size, second phase morphology, and static contact angle of A205-T7 aluminum alloy with water has been investigated. To study the effect of cooling rates, a sand casting with varying section thicknesses was made and subjected to T-7 heat treatment (solutionizing and over-aging). Microstructural analysis and water contact angle measurements have been performed on the fully polished specimens using optical microscopy and a goniometer respectively. Furthermore, the effect of droplet size (4 μL to 10 μL) on the wettability of alloys with water was studied. The hardness of the specimens was evaluated using micro hardness measurements. The results show that by increasing the casting thickness, the average grain size increased from 27 μm to 75 μm and the static contact angle was decreased from 76 to 70 degrees.
