A fracture mechanism and forming limit in cylindrical deep-drawing below 47
3 K was investigated for commercially rolled sheet of magnesium alloy AZ31.
A small punch radius, of which the ratio to thickness was 2.5, was adopted
intentionally. At room temperature, a brittle fracture under a very small
punch load occurred at an early stage on the punch shoulder near the bottom
. It was confirmed by stretch bending tests that the fracture was caused by
bending under high tension, which deeply concerned with high yield stress
and little local elongation of this material. The forming limit was dominat
ed by this mechanism up to 453 K in semi-static drawing.