M6 Grade 9.8 Torque Specification

Torque Values by Surface Condition

Stress area: 20.12 mm² · Proof load: 13,078 N · Clamp load (75%): 9,808 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	11.8	8.7	104.4	120.3
Oiled	0.15	8.8	6.5	77.9	89.7
Zinc Plated	0.18	10.6	7.8	93.8	108.1
Waxed	0.1	5.9	4.4	52.2	60.2
MoS₂	0.12	7.1	5.2	62.8	72.4
Galvanized	0.25	14.7	10.8	130.1	149.9

Stress area: 22.03 mm² · Proof load: 14,320 N · Clamp load (75%): 10,740 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	12.9	9.5	114.2	131.5
Oiled	0.15	9.7	7.2	85.9	98.9
Zinc Plated	0.18	11.6	8.6	102.7	118.3
Waxed	0.1	6.4	4.7	56.6	65.3
MoS₂	0.12	7.7	5.7	68.2	78.5
Galvanized	0.25	16.1	11.9	142.5	164.2

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 650 MPa × 20.12 mm² = 9,808 N

Step 2 — Torque (dry): T = 0.20 × 0.0060 m × 9,808 N = 11.8 N·m

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

Heavy-duty automotive, high-performance machinery (limited availability, mostly M16 and smaller)

• 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.

SizeM6

Class9.8

Diameter6 mm

Pitch (coarse)1.0 mm

Tensile900 MPa

Yield720 MPa

Proof650 MPa