GRAIN REFINEMENT EFFECT OF CORE ALLOY ON FORMING CHARACTERISTICS OF 4343/3003/4343 ALUMINUM CLAD SHEET

摘要

This study aimed to investigate the effects of grain refinement on forming and brazing characteristics of three-layer 4343/3003/4343 aluminum clad sheets. The clad sheets with 0.7 mm thickness were fabricated by hot roll bonding process. Al-10Ti master alloy was used for grain refining of 3003 Al-Mn core alloy. The Ti inoculation level was changed up to 0.1%. The forming characteristic of the clad sheets was strongly dependent on the recrystallization microstructure feature according to Ti inoculation level and stress relief annealing condition. 0.01～0.1%Ti inoculation treatment significantly improved the biaxial formability of the clad sheets at room temperature by 2 times or more. Ti solute dissolution of a significant level, 0.06%, from the core layer into the clad layer effectively refined α-Al cells and eutectic Si particles of the resolidified filler layer, resulting in bonding strength increment of the brazed clad sheets. The sagging resistance was improved with increasing Ti inoculation level, because the core strengthening effect due to Ti solute and its intermetallic compound was bigger than the weakening effect due to erosion phenomenon.