Metric Property Class 10.9
Class 10.9 is quenched-and-tempered alloy steel used in heavy machinery and high-preload joints. Close to SAE Grade 8 in strength, not interchangeable with it.
| Marking | 10.9 plus manufacturer ID (required from M5 on marked products) |
|---|---|
| Matching nut | ISO 898-2 class 10 |
Mechanical properties (ISO 898-1)
| Class | Tensile Rm (min) | Yield (min) | Proof stress | Hardness |
|---|---|---|---|---|
| 10.9 | 1040 MPa | 940 MPa | 830 MPa | 320 - 380 HV |
These tables carry the same figures as the printed sheet below.
The printed sheet
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Text version of this sheet
ISO 898-1 · property class 10.9 · high strength
FIELD IDENTIFICATION
What it is
Class 10.9 is quenched-and-tempered alloy steel used in heavy machinery and high-preload joints.
Close to SAE Grade 8 in strength, not interchangeable with it.
MFG
10.9
Marking
10.9 plus manufacturer ID (required from M5 on marked products)
Matching nut
ISO 898-2 class 10
Head stamped 10.9 + manufacturer ID
Mechanical properties (ISO 898-1)
Class
10.9
Tensile Rm (min)
Yield (min)
1040 MPa
Proof stress
940 MPa
Hardness
830 MPa
320 - 380 HV
Key points
Electroplated 10.9 needs a hydrogen-embrittlement-controlled process; zinc-flake coatings are common.
Governing standards: ISO 898-1:2013; ISO 898-2:2022. Editions shown are the latest confirmed as of September 2026. The drawing and the governing standard always take
precedence over this sheet.
torquing any fastener. Verify the current governing standard, project documents, OEM requirements, size, thread, coating and lot certification. To the fullest extent permitted by law, The Fastener App disclaims liability
arising from reliance on this reference.
Fastener Guide reference FG-13AD90 · thefastenerapp.com/fastener-guide/technical-reference/metric-property-class-10-9 · © The Fastener App. Reference only — verify the current governing standard, drawing and manufacturer data before specifying or installing.
