Overview
ISO 16120-4:2017 - "Non-alloy steel wire rod for conversion to wire - Part 4: Specific requirements for wire rod for special applications" specifies quality, composition and inspection requirements for non-alloy steel wire rod with improved characteristics intended for drawing and/or cold rolling for special applications. This third edition (2017) is intended to be used with ISO 16120-1 (general requirements) and complements ISO 16120-2 (general-purpose wire rod).
Key topics and technical requirements
- Scope and designation: Grades are designated C##D2 (C = non-alloy steel; ## = indicative average carbon; D = for drawing; 2 = special applications). Steels can alternatively be ordered by tensile strength (e.g., C##D2 – 1020).
- Chemical composition: Heat-analysis limits are specified for a wide range of carbon grades (C3D2 to C98D2) and major elements (Si, Mn, P, S, Cu, Ni, Cr, Mo, Al, N). The standard permits agreed microalloying additions (e.g., Cr, V) by purchase agreement.
- Product vs heat analysis tolerances: Permissible deviations are defined (example: carbon ±0.020 to ±0.040 depending on grade; Si ±0.040; Mn ±0.060; P and S +0.005).
- Internal soundness and surface quality: The rod shall be free from detrimental internal or surface discontinuities (shrink holes, cracks, folds, scabs, burrs).
- Surface discontinuity limits: Maximum depths and lengths for surface discontinuities are specified for round rod; smaller diameters have stricter depth limits (typical radial depth limits are on the order of 0.15–0.20 mm depending on diameter).
- Decarburization: Rules for complete and partial decarburization inspection apply to higher carbon grades (C42D2 to C98D2); complete decarburization is not permitted.
- Microstructure and inclusions: Requirements cover non-metallic inclusions, core segregation, microstructure (resolvable pearlite) and a cementite network requirement added in this edition.
- Mechanical and surface characteristics: Tensile strength ranges and scale/mechanical damage criteria are defined or referenced.
Applications and users
ISO 16120-4:2017 is used by:
- Steel producers and mills producing wire rod for high-drawability or cold-rolled conversion
- Wire-drawing and cold-rolling manufacturers who require predictable feedstock properties
- Quality/control laboratories and inspection bodies for material verification and acceptance testing
- Procurement and engineering teams specifying wire rod for special applications that demand tighter chemical, mechanical or surface controls
Related standards
Keywords: ISO 16120-4:2017, non-alloy steel wire rod, wire rod for special applications, chemical composition, decarburization, surface discontinuities, tensile strength, wire-drawing.
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