Effect of Intermediate Heat·Brazing Heat Treatments on the Mechanical Properties of 3527/4343 Aluminum Clad Sheet Manufactured by Strip Casting/Clad Rolling

다국어 초록 (Multilingual Abstract)

This study attempted to produce a clad sheet with strip casted AA3527 alloy and AA4343 alloy, and attempted to investigate the effect of intermediate heat treatment and brazing treatment on the mechanical properties (hardness, tensile properties) of 3527/4343 aluminum clad sheet. The core sheet (manufactured by strip casting), AA3527 alloy (composition: Al-0.54Si-0.55Fe-0.76Cu-1.18Mn-0.03Mg-0.32Cr-0.08Ti), and surface thin sheet for brazing, AA4343 alloy (composition: Al-7.38Si-0.138Fe-0.01Ti) underwent hot rolling and cold rolling, and then a roll bonding for finishing. The overall thickness of the clad sheet was measured at approximately 0.22mm (AA3527: 0.20mm, AA4343: 0.02mm). The intermediate heat treatments were conducted on the conditions of 360℃-400℃/14 hours. Then, the samples underwent 100 minutes of brazing treatment at temperatures of 610℃. In the 3527 alloy region, Al, Al6Mn and AlFeMnSi phases were observed. In the case of 4343 region, Al, eutectic Si, AlFeSi phases were identified. The microstructure observation results represented partial recovery and recrystalization at temperatures of 360℃ and 380℃ heat treatment conditions, and complete recrystalization was observed at 400℃ condition. Tensile and yield strengths decreased (249.8MPa->203MPa, 203.8MPa->88MPa) and elongation increased (7.6%->10.4%) as heat treatment temperature increased. After brazing treatment, recrystalization and grain growth appears regardless of intermediate heat treatment temperature. Erosion in directed from partial 4343 alloy region to 3527 alloy region was occasionally found. Tensile properties after brazing are identified to be similar regardless of intermediate heat treatment conditions