M10 Grade 8.8 Torque Specification

Torque Values by Surface Condition

Stress area: 58.0 mm² · Proof load: 33,640 N · Clamp load (75%): 25,230 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	50.5	37.2	447.0	515.0
Oiled	0.15	37.8	27.9	334.6	385.5
Zinc Plated	0.18	45.4	33.5	401.8	463.0
Waxed	0.1	25.2	18.6	223.0	257.0
MoS₂	0.12	30.3	22.3	268.2	309.0
Galvanized	0.25	63.1	46.5	558.5	643.4

Stress area: 61.2 mm² · Proof load: 35,496 N · Clamp load (75%): 26,622 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	53.2	39.2	470.9	542.5
Oiled	0.15	39.9	29.4	353.1	406.9
Zinc Plated	0.18	47.9	35.3	424.0	488.4
Waxed	0.1	26.6	19.6	235.4	271.2
MoS₂	0.12	31.9	23.5	282.3	325.3
Galvanized	0.25	66.6	49.1	589.5	679.1

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 580 MPa × 58.0 mm² = 25,230 N

Step 2 — Torque (dry): T = 0.20 × 0.0100 m × 25,230 N = 50.5 N·m

Proof stress per ISO 898-1:2013 Table 4. Stress area per ISO 898-1 Annex A. K-factor per VDI 2230.

Automotive engines, structural connections, high-strength machinery, flanged joints — the most common high-strength grade

• Torque values are for standard hex bolts with ISO metric threads. Socket head cap screws may have different requirements.
• Lubrication reduces required torque significantly — using dry torque values on lubricated bolts risks exceeding yield strength.
• For critical or safety-related applications, always consult the manufacturer's specifications or applicable design standard (e.g., VDI 2230).
• Re-used bolts may have altered friction characteristics. Inspect threads before reuse.

SizeM10

Class8.8

Diameter10 mm

Pitch (coarse)1.5 mm

Tensile800 MPa

Yield640 MPa

Proof580 MPa