What mechanical properties are listed in a round steel material certificate?

A round steel material certificate (Mill Test Report, MTR) includes critical mechanical properties that define performance. These typically cover tensile strength (maximum stress before fracture) – for example, ASTM A36 round steel requires 400–550 MPa, while EN S355JR specifies 470–630 MPa. Yield strength (stress at permanent deformation) is key too: ASTM A36 needs ≥250 MPa, and EN S355JR ≥355 MPa. Elongation percentage (stretch before breaking) ensures ductility – ASTM A36 mandates ≥23% (200mm gauge length), EN S355JR ≥22%. For cold or high-impact use, Charpy V-notch impact test results are added (e.g., ≥27 J at -20°C for EN S355J2). These properties are tested per standards like ASTM E8 (tensile) or EN 10002-1, with values linked to the round steel's heat number for traceability. Customers use these to confirm suitability for applications like shafts or fasteners, where strength and ductility prevent failures.