brass casting 80/20

The bending stress exceeds the yield stress of the material.

If it cracks, it's ultimate stress has been exceeded.

Hi moonlight,

I don't understand well the crack direction "parallel to the width"

The crack is normal to the length (the direction in which the specimen strains)? This is the normal failure direction when strain exceeded the rupture elongation (for this type of material about 35% in a 2" length).

Have you performed tensile testing of casted material?

Which was the yield strength and the rupture elongation?

Which is the bending radii and angle? What theoretical elongation do you have for this bending values in the convex side of bended specimen?

Has the casting some inclusions, segregations, etc?

This would help to determine the root cause of failure.

Kind regards

Most cast materials are brittle. If you bend them cold, they will crack across the bend. I didn't take any non-ferrous metallurgy courses, but you may be able to inprove ductility with a heat treatment. Check with your material supplier or ASM.