ISO 1035-3:1980

Overview - ISO 1035-3:1980 (Hot-rolled steel bars - Dimensions of flat bars)

ISO 1035-3:1980 specifies the dimensions and nominal masses for metric-series hot-rolled steel flat bars. The standard provides a tabulated set of preferred and second-preference widths and masses per unit length, and establishes the default rule for dimensional tolerances. Mass values in the table are calculated using a steel density of 7.85 kg/dm³. This edition (1980) cancels and replaces ISO Recommendation R 1035/3‑1969.

Key topics and technical requirements

• Scope: Metric-series hot-rolled steel flat bars - dimensional sizes and associated masses.
• Preferred sizes: A table lists the preferred and second-preference widths and the mass per unit length for each size (dimensions in millimetres).
• Tolerances: Unless otherwise specified in the purchase order, dimensional tolerances are the normal tolerances defined in ISO 1035-4. The standard notes that tighter tolerances will be the subject of a future International Standard.
• Mass calculation: Mass values are based on a steel density of 7.85 kg/dm³ (explicitly stated in the document).
• Edition and development: First edition published 1980-11-01; developed by ISO/TC 17 (Steel).

Applications - who uses ISO 1035-3 and why

ISO 1035-3 is used by organizations that specify, produce, buy, or inspect hot‑rolled flat steel bars, including:

• Steel mills and hot-rolling producers for consistent product sizing and mass reporting.
• Metal fabricators and machine shops for material selection and cost/mass calculations.
• Structural and mechanical engineers who need standardized bar dimensions for design and detailing.
• Procurement and quality-control teams to define order requirements and acceptance criteria.
• Distributors and stockholders to standardize inventory and interoperability across suppliers.

Practical benefits:

• Ensures interchangeability of hot-rolled flat bars across suppliers and borders.
• Simplifies specification writing and reduces ambiguity in orders.
• Provides a common basis for mass-per-length calculations used in estimating and logistics.

Related standards

• ISO 1035-4 - Hot-rolled steel bars: tolerances for round, square and flat bars (metric series) - referenced for normal tolerances.
• ISO 1035 series (other parts) - for dimensions and tolerancing of related bar forms.

Keywords: ISO 1035-3:1980, hot-rolled steel flat bars, flat bar dimensions, metric series, dimensions and tolerances, preferred sizes, mass per unit length, ISO 1035-4.