GRADE MARKINGS FOR FASTENERS

Grade Markings for Metric Fasteners

Markings of Screws

(According to ISO 898 – Part I)

Property Class 3.6 4.6 4.8 5.6 5.8 6.8 8.8 9.8 10.9 12.9
Marking 1),2) 3.6 4.6 4.8 5.6 5.8 6.8 8.8 9.8 10.9 12.9
1)The full-stop in the marking symbol may be omitted.
2)
When low carbon martensitic steels are used for property class 10.9 the symbol 10.9 shall be underlined: 10.9
Identification with the manufacturer’s mark and the property class is mandatory for hexagon screws 3.6 to 12.9 and socket head cap screws 8.8 to 12.9 with thread diameter d> 5mm, where the shape of the screw always allows it – preferably on the head.
Grade Mark Hex Bolt ABCD 8.8 - Technical Spec

Examples of markings on hexagon screws.

Grade Mark Socket Head ABCD 12.9 - Technical Spec

Examples of markings on socket head cap screws.

Marking Of Nuts

(According to ISO 898 – Part II)

Property Class 04 05 4 5 6 8 9 10 12
Either designation Symbol 04 05 4 5 6 8 9 10 12
Code (Clock Symbol) Symbol Hex Nut Grade Mark 4 - Technical drawing - Grade 04 Grade Mark 5 - technical Spec Grade Mark 4 - Technical Spec Grade Mark 5 - Technical Spec Grade Mark 6 - Technical Spec Grade Mark 8 - Technical Spec Grade Mark 9 - Technical Spec Grade Mark 10 - Technical Spec Grade Mark 12 - Technical Spec - Nut
Identification with the manufacturer’s mark and property class is mandatory for hexagon nuts with thread diameter d ≥ 5 mm.  The hexagon nuts must be marked with an indentation on the bearing surface or on the side or by embossing on the chamfer. Embossed markings must not protrude beyond the bearing surface of the nut.

*All information is strictly informative