ISO 4997:2025

Overview

ISO 4997:2025 - Cold-reduced carbon steel sheet of structural quality - specifies requirements for cold‑reduced carbon steel sheet intended for structural applications. It covers grades CR220, CR250, CR280, CR320 and CH550, typically produced without microalloying. The standard defines dimensions (commonly 0.36 mm to 3 mm thickness, widths 600 mm and over), manufacturing conditions, chemical and mechanical requirements, surface quality, testing and inspection, coil size, marking and purchaser information.

Key topics and technical requirements

• Grades and scope: Applies to cold‑reduced structural grades CR220–CR320 and CH550; excludes commercial/drawing qualities and several higher formability or hardness‑based steels (see Related Standards).
• Dimensions & product form: Supplied in coils and cut lengths; sheet <600 mm may be slit from wide coils and still considered sheet.
• Chemical composition: Heat analysis limits for C, Mn, P, S are specified (e.g., C up to 0.15–0.25% depending on grade; Mn up to 1.20–1.50%). Limits for Cu, Ni, Cr, Mo and trace microalloying elements (Nb, V, Ti) are also given.
• Product and heat analysis: Manufacturer heat analysis required for each heat; purchaser may request product analysis with defined tolerances and agreed sampling methods.
• Mechanical properties: Minimum yield and tensile strengths and elongation values are specified by grade (for example, CR220: yield 220 MPa, tensile 300 MPa; CR320: yield 320 MPa, tensile 400 MPa). CH550 is a high‑strength grade with yield approaching tensile strength.
• Manufacture & condition: Defines cold‑reduction and annealing practices; skin‑pass (light cold rolling) is normal except for CH550 and affects surface finish and formability.
• Weldability & fabrication: Guidance on weldability (e.g., spot welding difficulty increases above 0.15% C; CH550 not recommended for welding due to heat‑affected strength loss).
• Surface & finish: Surface quality classifications (A unexposed, B exposed), recommended roughness references, oiling and coating suitability.
• Testing & inspection: Tensile testing, sampling, retests, workmanship, marking and information to be supplied by purchaser are defined.

Applications and users

ISO 4997:2025 is intended for steel producers, structural fabricators, welders, design engineers, quality inspectors and procurement teams specifying cold‑reduced structural sheet for bolting, riveting, bending, forming and welding applications. It’s useful when specifying material performance, ensuring consistent chemistry, mechanical behavior and surface condition for fabricated steel structures.

Related standards

• ISO 3574 - drawing/commercial qualities (excluded)
• ISO 5954 - cold‑reduced sheet by hardness requirements (excluded)
• ISO 13887 - higher strength with improved formability (excluded)
• ISO 14590 - high tensile strength, low yield point, improved formability (excluded)

Keywords: ISO 4997:2025, cold‑reduced carbon steel sheet, structural quality, CR220, CR250, CR280, CR320, CH550, chemical composition, mechanical properties, weldability, surface quality.