"During the solidification process in casting, hot tearing may occur. It is a severe defect that normally involves the formation of a macroscopic tear, which generates cracks either on the surface or inside the casting. Over the past decades, many strategies have been developed to evaluate the hot tearing tendency. Unfortunately, most of the tests can only provide qualitative information. Therefore, a reliable and quantitative test to evaluate hot tearing in aluminum alloys is highly desirable. To address this issue, WPI and CANMET MTL (both members of the Light Metal Alliance) jointly developed a quantitative hot tearing test and established a specific methodology. Using a constrained rod mold, the hot tearing formation can be quantitatively studied by measuring the contraction force, time and temperature during solidification for a restrained casting or linear contraction, time and temperature for a relaxed casting. This study investigated cast aluminum alloys A380.1 and A390 and wrought aluminum alloys 6061 and 7075. The results show that wrought aluminum alloys have a much stronger hot tearing tendency than cast aluminum alloys based on a quantitative analysis. Also, the study involves the effects of adding strontium and oxides respectively into the cast aluminum alloy A380.1. Compared with the pure A380.1 alloy, the introduction of strontium decreases the hot tearing tendency, while the inclusion of oxide greatly increases the hot tearing. The information obtained through these tests provides a database of hot tearing phenomenon and establishes a new hot tearing index."
| Identifer | oai:union.ndltd.org:wpi.edu/oai:digitalcommons.wpi.edu:etd-theses-1940 |
| Date | 20 August 2012 |
| Creators | Wu, Qinxin |
| Contributors | Diran Apelian, Advisor, Richard D. Sisson, Jr., Department Head, Libo Wang, Committee Member |
| Publisher | Digital WPI |
| Source Sets | Worcester Polytechnic Institute |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Masters Theses (All Theses, All Years) |
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