Effect of Electrical Current Stressing on the Deterioration of Tensile Properties of High Strength Al-Cu 2017 Alloy

Autor: Kuo-Yi Chung, 鐘國益
Rok vydání: 2007
Druh dokumentu: 學位論文 ; thesis
Popis: 95
The study of relationship between mechanical properties and thermal behavior of the heat treatable aluminum alloy was well known. However, there were few discussions between electrical current stressing and mechanical properties. In this study, mechanical properties and microstructure of the high strength 2017-T351 Al-Cu alloy were discussed by using direct current flow at current density up to 2000A/cm2. The results showed the decreasing on the tensile properties of 2017-T351 was notable by electrical current stressing. It related to electrical current effect. There were obviously deterioration in hardness of cathode end, the tensile strength and elongation, the mechanical properties difference between the cathode end and anode end of the 2017 bulk specimens was not only effect of temperature, but also electrical current stressing. The similar serration phenomenon observed in tensile stress-strain curve after electrical current stressing and solution treatment ( 768K holding 1h and then quenched in water, i.e., T4). The solution-treated samples were tested within 20 min in tension. The serration curve is called “dynamic strain aging” (DSA). If the solution-treated samples were tested in tension after natural aging 3day (T4NA), there was no serration curve. At this time if we tested T4NA samples with electrical current stressing in tension, the curve was serrulated again, so we demonstrated the serration phenomenon was related to electrical current stressing. The electrical current stressing will dissolve precipitates. The dissolved precipitates will cause the strength of 2017-T351 decreasing. It makes solute atoms solve back to matrix, when solute concentration is enough, it would interact with dislocation to cause DSA.
Databáze: Networked Digital Library of Theses & Dissertations
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