What is the primary heat treatment specified for high-strength fastener steel?

Quenching and tempering are required to achieve the desired mechanical properties and toughness.

What is the maximum permissible Sulphur and Phosphorus content?

It is generally limited to 0.040% max to ensure adequate toughness and prevent embrittlement under stress.

Which property classes of fasteners does this standard primarily support?

It provides the material basis for manufacturing high-strength structural fasteners typically matching property classes 8.8S and 10.9S.

IS 1775

: 1993

Steel for high strength structural fasteners

CurrentSpecializedSpecificationMaterials Science · Fasteners, Bolts and Anchors

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This standard prescribes the requirements for steel used in the manufacture of high-strength structural fasteners, including bolts, nuts, and washers. It specifies the chemical composition, heat treatment, and mechanical properties necessary to ensure reliability in critical slip-resistant and dynamic structural connections.

Specifies the requirements for steel used for the manufacture of high strength structural fasteners.

Quick Reference Values

Max Sulphur content0.040 %

Max Phosphorus content0.040 %

Minimum Tensile Strength (Property Class 8.8)800 MPa

Minimum Yield Stress (Property Class 8.8)640 MPa

Minimum Tensile Strength (Property Class 10.9)1040 MPa

Minimum Yield Stress (Property Class 10.9)940 MPa

Practical Notes

Steel for high-strength fasteners must be fully killed and suitably heat-treated (quenched and tempered) to achieve uniform mechanical properties.

Strict control over Sulphur and Phosphorus limits is critical during manufacturing to prevent brittleness and hydrogen embrittlement.

Always ensure the Mill Test Certificate (MTC) of the raw material verifies conformity to this standard before heading or threading the bolts.