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What causes looper lines in drawn aluminum?


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October 23, 2008 8:57PM

Looper lines or also known as "roping" in aluminum is a form of "surface roughening" which occurs during deep drawing or drawing and ironing operations. The origin of looper lines occur during ingot casting, homogenization and rolling practices. The coarse grain structure are formed during the hot rolling or intermediate annealing when drawn into fine "fiber" like structure during temper rolling. In annealed sheets, if these fibers fail to recrystalize, the fibers can produce looper lines. Looper lines also can form because of segregated constituent or solute. If the coarse grains with segregation persist the reheating, this can produce looper lines.