ISO 898-1 Mechanical Properties of Fasteners Made of Carbon Steel and Alloy Steel - Coarse-Threaded and Fine-Threaded

The standard “ISO 898-1 Mechanical properties of fasteners made of carbon steel and alloy steel - Part 1: Bolts, screws and studs of specified property classes - Coarse thread and fine thread” developed by the International Organization for Standardization (ISO) describes the mechanical and physical properties of bolts, screws and studs made of carbon steel and alloy steel when tested in an ambient temperature range between 10 degrees and 35 degrees.

Fasteners (the term used to describe bolts, screws, and studs) that meet the requirements of this standard are evaluated within that ambient temperature range. They may not maintain the specified mechanical and physical properties at higher or lower temperatures.

Fasteners that meet the requirements of this standard are used in applications between -50°C and +150°C. Users are advised to consult an experienced fastener professional when determining the appropriate selection for a specific application for temperatures outside the -50°C to +150°C range, and for temperatures up to a maximum of +300°C.

Information on the selection and application of steels for use at low and high temperatures is given in, for example, EN 10269, ASTM F2281 and ASTM A320/A320M standards.

Some bolts and screws may not meet the tensile or torsion requirements of this standard because the geometry of their heads reduces the shear area at the head compared to the tension area at the thread. These include bolts and screws with undershot or countersunk heads.

This standard applies to the following types of bolts, screws and studs:

• Made of carbon steel or alloy steel
• With triangular ISO metric screw thread in accordance with ISO 68-1 standard
• Coarse thread from M1,6 to M39 and fine thread from M8×1 to M39×3
• Diameter/pitch combinations in accordance with ISO 261 and ISO 262 standards
• With thread tolerances in accordance with ISO 965-1, ISO 965-2 and ISO 965-4 standards

This standard does not apply to set screws and similar threaded fasteners that are not under tensile stress (see ISO 898-5).

This standard does not include requirements for features such as:

• Weldability
• Corrosion resistance
• Resistance to shear stress
• Torque / clamp force performance (see ISO 16047 standard test method)
• Fatigue resistance

In short, ISO 898-1 is a globally recognized standard that defines the mechanical properties of fasteners such as bolts, screws, and studs made of carbon steel and alloy steel. This standard is crucial for ensuring the reliability, safety, and performance of fasteners used in mechanical assemblies, construction, automotive, and heavy machinery applications.

The ISO 898-1 standard applies specifically to:

• Bolts, screws and studs having a nominal thread diameter of M1.6 to M39, a coarse thread or a specified fine thread pitch and a property class marking
• Fasteners made of carbon steel or alloy steel
• Products that are not subjected to special heat treatment after production (except quenching and tempering)

This standard does not apply to:

• Fasteners requiring different properties (e.g. high corrosion resistance or non-ferrous materials)
• Fasteners with customized designs or dimensions outside the specified ranges
• Threaded rods, self-tapping screws and wood screws (covered by other standards)

The main features of the ISO 898-1 standard are:

• Property classes: This standard defines a series of property classes (e.g., 4.6, 8.8, 10.9, 12.9) that indicate the mechanical strength of fasteners. These are two-digit codes. The first number represents 1/100 of the nominal tensile strength in MPa. The second number represents the ratio of yield strength to tensile strength.
• Mechanical requirements: This standard provides precise test methods and values ​​for:
  • Tensile strength
  • Yield strength or proof load
  • Elongation after fracture
  • Hardness (Brinell, Rockwell or Vickers)
  • Impact resistance (for larger diameter fasteners or special applications)
• Test conditions: Tests are performed at room temperature (10°C to 35°C). Results may be affected by manufacturing processes such as heat treatment, surface condition, and threading.

The ISO 898-1 standard has been widely adopted in industries that demand consistency and reliability in bolted connections. This standard provides:

• Interchangeability between manufacturers
• Predictable performance under mechanical stress
• A basis for design calculations and safety factors
• Guidance for quality control and compliance testing

Consequently, the ISO 898-1 standard plays a critical role in ensuring the mechanical integrity of fasteners used in countless applications. By adhering to this standard, manufacturers and engineers can ensure that fasteners will perform as expected under mechanical loads, reduce the risk of failure, and increase overall safety and reliability. A solid understanding of the ISO 898-1 standard is essential for correctly selecting and specifying fasteners in technical design and procurement.

Our organization, which has been supporting businesses across all sectors for years through a wide range of testing, measurement, analysis, and evaluation activities, boasts a strong team of employees who closely follow global developments in science and technology and are constantly improving themselves. In this context, we also provide testing services in accordance with the ISO 898-1 "Mechanical properties of fasteners made of carbon steel and alloy steel - Part 1: Bolts, screws, and studs with specified property classes - Coarse-threaded and fine-threaded."