Strain and hardness distributions in the cup wall drawn with ironing of 3004-H19 aluminum alloy sheets

Abstract

The strain and hardness distributions in the drawn cup walls of the cold rolled 3004 aluminum alloy sheet were measured and discussed on the anisotropy and the effect of simultaneous wall ironing during cup drawing. The thickness strain in the cup wall is large along the TD direction of the sheet and is small along the RD direction. This phenomenon is considered to be corresponding to the anisotropy of r value in the cold rolled 3004 aluminum alloy sheet. In RD direction, the ears grow up at the cup wall edge because of the large radial strain balanced with small thickness strain. The sizing work that means ironing a part of the thicker cup wall tends to unify the distributions of thickness strain, and then the ears at the edge of cup wall become to be small. The hardness of the cup wall decreases by drawing to less than the material, and the hardness drop seems to be remarkable especially in TD direction where the thickness strain is large and the sizing work is heavy. The cause of hardness drop is considered to be due to the change of work hardened metal structure that depends on the additive strain through the complex different strain passes during cup drawing.