ISO 1035:2026

Overview

ISO 1035:2026 provides a comprehensive international standard for the dimensions, shape, mass, and tolerances of hot-rolled steel bars in metric series. Developed by ISO Technical Committee ISO/TC 17, Steels, this standard covers various cross-sectional shapes of steel bars including round, square, flat, hexagonal, and octagonal forms. ISO 1035:2026 is designed to harmonize the specification of hot-rolled steel bars across industries, supporting consistency in quality and manufacturing processes worldwide. This document supersedes previous editions (ISO 1035-1:1980 through ISO 1035-4:1982) with revised and expanded requirements.

Key Topics

• Scope of Application:
  • Covers hot-rolled round bars (5.5 mm to 400 mm diameter), square bars (5.5 mm to 300 mm side), flat bars (3 mm to 60 mm thickness, 10 mm to 200 mm width), hexagonal bars (8 mm to 70 mm across flats), and octagonal bars (16 mm to 40 mm across flats).
  • Metric series ensures widespread compatibility for international use.
• Dimensional Specifications:
  • Detailed preferred dimensions, masses per unit length, and sectional areas for each type of bar.
  • Tolerance classes (normal, fine, superfine for rounds and squares; class N, F for hexagons and octagons) ensure precision based on application needs.
• Shape & Form Control:
  • Permissible levels of ovality and out-of-squareness for each bar shape help maintain cross-sectional integrity.
  • Requirements for straightness and, when specified, twist are described, enhancing structural reliability.
• Contractual Flexibility:
  • Provisions for supplier and purchaser agreements on non-standard dimensions, tolerances, and special requirements such as sharp corners or radius.
• Measurement and Tolerances:
  • Systematic tables address tolerances on length, width, thickness, and straightness.
  • Recommendations for distance from bar ends for tolerance measurements ensure uniformity in product acceptance.

Applications

• Structural Engineering: Used as fundamental building elements for construction, bridges, frameworks, and reinforcement.
• Automotive and Machinery: Essential in manufacturing components that require consistent shape and mass, supporting mechanical performance.
• General Manufacturing: Suitable for fabrication of parts in various industries where standardized steel bar dimensions are critical for production efficiency and interchangeability.
• Procurement and Quality Assurance: Provides a clear reference for ordering, inspection, and acceptance of hot-rolled steel bars on a global scale.

By adopting ISO 1035:2026, organizations ensure that hot-rolled steel bars meet international best practices for dimensional accuracy, physical consistency, and mass properties - supporting reliable design, manufacturing, and structural safety.

Related Standards

For compatibility and further technical information, ISO 1035:2026 references and relates to several international and regional standards:

• ISO 6929: Steel Products – Vocabulary
• EN 10058, EN 10059, EN 10060, EN 10061: European standards for hot-rolled flat, square, round, and hexagonal steel bars
• GB/T 702: Hot-rolled steel bars – Dimensions, shape, mass, and tolerances (China)
• ASTM A6M: General requirements for rolled structural steel bars (USA)
• ISO 630 Series: Structural steels and technical delivery conditions
• ISO 7452: Tolerances on dimensions and shape for hot-rolled steel plates
• JIS G 3191, JIS G 3194: Japanese standards for hot-rolled steel bars

These references ensure alignment with global steel industry requirements and facilitate smooth international trade in steel products.

Keywords: hot-rolled steel bars, ISO 1035, steel bar dimensions, shape and tolerances, metric series steel bars, standard steel bar masses, structural steel standards, steel product specifications