M6 Grade 5.8 Torque Specification

Torque Values by Surface Condition

Stress area: 20.12 mm² · Proof load: 7,646 N · Clamp load (75%): 5,734 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	6.9	5.1	61.1	70.4
Oiled	0.15	5.2	3.8	46.0	53.0
Zinc Plated	0.18	6.2	4.6	54.9	63.2
Waxed	0.1	3.4	2.5	30.1	34.7
MoS₂	0.12	4.1	3.0	36.3	41.8
Galvanized	0.25	8.6	6.3	76.1	87.7

Stress area: 22.03 mm² · Proof load: 8,371 N · Clamp load (75%): 6,279 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	7.5	5.5	66.4	76.5
Oiled	0.15	5.7	4.2	50.4	58.1
Zinc Plated	0.18	6.8	5.0	60.2	69.3
Waxed	0.1	3.8	2.8	33.6	38.7
MoS₂	0.12	4.5	3.3	39.8	45.9
Galvanized	0.25	9.4	6.9	83.2	95.9

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 380 MPa × 20.12 mm² = 5,734 N

Step 2 — Torque (dry): T = 0.20 × 0.0060 m × 5,734 N = 6.9 N·m

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

General industrial fastening, equipment mounting, moderate structural loads

• 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

Class5.8

Diameter6 mm

Pitch (coarse)1.0 mm

Tensile520 MPa

Yield420 MPa

Proof380 MPa