Al 7003 합금의 열처리(T5, T6)에 따른 인장 및 고주기 피로 변형 거동

다국어 초록 (Multilingual Abstract)

Tensile and high-cycle fatigue defomation behavior due to heat treatment (T5, T6) on Al 7003 alloy were investigated. Aluminum 7003 alloy was produced through casting and extruding, and then heat treatments of T5(90 ℃, 5hrs. + 150 ℃, 16hrs.) and T6 (470 ℃, 3hrs., 80 ℃ and WQ solution processing, 14hrs + 120 ℃, 42hrs.) followed respectively. Using the two kinds of Al 7003 alloys to which different heat treatments were applied, microstructure analysis, tensile tests, room-temperature high-cycle tests, etc., were performed. The observation of microstructure showed that the average grain size was 3.8 μm for T5 alloy and 4.1 μm for T6 alloy. Both kinds of heat-treated alloys were analyzed to be Al-matrix and to have MgZn₂ and Fe-intermetallic phase; MgZn₂ with T6 condition had finer and more regular distribution compared to the one with T5 condition. The tensile results showed the following properties under the T5 heat treatment condition: tensile strength of 359.0MPa; yield strength of 326.1MPa, and; ductility of 28.0%. On the other hand, under the T6 condition, tensile strength was 411.6MPa, yield strength was 373.6MPa, and ductility was 26.3%. In other words, under the T6 heat treatment condition, relatively higher strength and minor decrease in ductility were obtained compared to those under the T5 condition. The high-cycle fatigue results showed that the fatigue limit (10<SUP>7</SUP>cycle) under the T5 heat treatment condition was 290MPa, and the fatigue limit (10<SUP>7</SUP>cycle) under the T6 condition was 320WPa. Under all stress conditions, the fatigue life of T6 alloy was verified to be longer than that of T5 alloy. Based on the observation on tensile and fatigue fracture surfaces, the excellent properties of the T6 heat-treated alloy were confirmed to cone from the effective reinforcement phases with small and uniform distribution generated by the heat treatment under such condition. Based on these results, Al 7003 alloy`s tensile and fatigue deformation mechanisms were also discussed.

목차 (Table of Contents)

• Abstract
• 1. 서론
• 2. 실험 방법
• 3. 결과 및 고찰
• 4. 결론
• 참고문헌