ISO 898 Mechanical Properties of Fasteners Made of Carbon Steel and Alloy Steel

The “ISO 898 Mechanical properties of fasteners made of carbon steel and alloy steel” standard, developed by the International Organization for Standardization (ISO), consists of a number of subsections published under the same title. Namely,

The standard “ISO 898-1 Part 1: Bolts, screws and studs of specified property classes - Coarse thread and fine thread” 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 when bolts, screws and studs are considered together) that comply with the requirements of this standard are evaluated in that ambient temperature range. They may not retain the specified mechanical and physical properties at higher temperatures or lower temperatures.

Fasteners that meet the requirements of this standard are used in applications between minus 50 degrees and plus 150 degrees. Users are advised to consult an experienced fastener metallurgist for temperatures outside the minus 50 degrees to plus 150 degrees range and up to a maximum of plus 300 degrees when determining the appropriate selection for a particular application.

Information on the selection and application of steels for use at low and high temperatures is provided in, for example, EN 10269, ASTM F2281 and ASTM A320/A320M. 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 in the thread. These include bolts and screws with undercut or countersunk heads. This standard applies to the following types of bolts, screws and studs:

Made of carbon steel or alloy steel
Having a triangular ISO metric screw thread in accordance with the ISO 68-1 standard
With coarse thread pitch from M1,6 to M39 and fine thread pitch from M8×1 to M39×3
Having diameter / tooth pitch combinations in accordance with ISO 261 and ISO 262 standards
Having 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.

It also does not specify requirements for features such as:

Weldability
Corrosion resistance
Resistance to shear stress
Torque / clamping force performance
Fatigue resistance

The standard “ISO 898-2 Part 2: Nuts with specified property classes” describes the mechanical and physical properties of nuts made of unalloyed steel or alloyed steel when tested in the ambient temperature range of 10 degrees to 35 degrees. This standard is valid for the following nuts:

ISO metric thread (ISO 68-1)
Diameter/pitch combinations according to ISO 261 and ISO 262 standards
Coarse pitch gear from M5 to M39 and fine pitch gear from M8×1 to M39×3
Thread tolerances according to ISO 965-1, ISO 965-2 or ISO 965-5 standards
04, 05, 5, 6, 8, 10 and 12 specified feature classes including test load
Three different nut styles: regular nuts (style 1), high nuts (style 2) and thin nuts (style 0)
Minimum outside diameter or width along straight sections of at least 1,45D
Can be combined with bolts, screws and studs having property classes in accordance with ISO 898-1 standard
Designed for use in applications between minus 50 degrees and plus 150 degrees or up to plus 300 degrees

Nuts conforming to the requirements of this standard are tested in the ambient temperature range of 10 degrees to 35 degrees and are used in applications from minus 50 degrees to plus 150 degrees, but these nuts are also used outside this range and up to plus 300 degrees for certain applications. It is possible that they may not retain their specified mechanical and physical properties at lower or higher temperatures. Therefore, it is the user's responsibility to determine the appropriate selections based on the service environment conditions of the assembly.

For additional specifications applicable to hot dip galvanized nuts, the ISO 10684 standard applies.

For nuts designed for specific applications, the ISO/TR 16224 standard applies.

This standard does not specify requirements for functional characteristics such as:

Prevailing torque characteristics (ISO 2320)
Torque/clamp force characteristics (ISO 16047 for test method)
Weldability
Corrosion resistance

The standard "ISO 898-3 Part 3: Plain washers with specified property classes" describes the mechanical and physical properties of plain washers designed for use in bolted connections with bolts, screws, studs and nuts having a specified property class in accordance with ISO 898-1 and ISO 898-2 standards. These types of washers can also be used with other fasteners such as screws that form their own mating threads.

Washers meeting the requirements of this standard are rated for the ambient temperature range of 10 degrees to 35 degrees. They may not retain the specified mechanical and physical properties at elevated or low temperatures. Washers meeting the requirements of this standard are used in applications with a temperature range of minus 50 degrees to plus 150 degrees. Users are advised to consult an experienced fastener professional when determining appropriate selections or for critical applications for temperatures outside this range and up to a maximum of plus 300 degrees.

This standard applies to the following flat fixed and non-fixed washers made of carbon steel or alloy steel with a thickness of 0,2 mm to 12 mm:

Plain washers (serrated, ribbed or chamfered or unchamfered)
Square washers
Square hole washers
Shaped plates

This standard does not specify requirements for the following characteristics:

Corrosion resistance
Weldability

The standard “ISO 898-5 Part 5: Set screws and similar threaded fasteners not under tensile stresses” describes the mechanical properties of set screws and similar threaded fasteners made of carbon steel or alloy steel with nominal thread diameters from 1,6 mm to 24 mm, not under tensile stresses.

The mechanical and physical properties are valid when tested at an ambient temperature between 10 degrees and 35 degrees and will vary at higher or lower temperatures.

This standard does not apply to set screws that require the following special features:

Specified tensile stresses (ISO 898-1)
Weldability
Corrosion resistance
The ability to withstand temperatures above plus 300 degrees or below minus 50 degrees.

Set screws made of free-cutting steel should not be used above 250 degrees.

The standard “ISO 898-7 Part 7: Torsion test and minimum torques for bolts and screws with nominal diameters between 1 mm and 10 mm” describes a torsion test method for determining the failure torque of bolts and screws with nominal diameters between 898 mm and 1 mm having certain property classes according to ISO 1-10. This method is applicable to bolts and screws with threads less than M898 for which failure and test loads are not specified in ISO 1-32 and to short bolts and screws with nominal diameters between 3 mm and 10 mm which cannot be subjected to tensile testing. The minimum failure torques for hexagon socket set screws are not applicable to this method.

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