Z-quality (through thickness) testing is usually specified where main design concern is high loads perpendicular to the plate surface. 16 mm – 100 mm thickness of the product material is cut out perpendicular to the surface (in the thickness direction). The test specimens are strained and broken by a tensile tester. Z quality of materials are determined according to percentage cross-sectional contraction of the rupture zone. It specifically measures ductility of materials rather than strength.
TS EN 10164: Steel products with improved deformation properties perpendicular to the surface of the product – Technical delivery conditions