M64 Grade 12.9 Torque Specification

Torque Values by Surface Condition

Stress area: 2676.0 mm² · Proof load: 2,595,720 N · Clamp load (75%): 1,946,790 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	24918.9	18379.2	220551.0	254103.0
Oiled	0.15	18689.2	13784.4	165413.4	190577.5
Zinc Plated	0.18	22427.0	16541.3	198495.8	228692.6
Waxed	0.1	12459.5	9189.7	110275.9	127052.0
MoS₂	0.12	14951.3	11027.5	132330.2	152461.4
Galvanized	0.25	31148.6	22974.0	275688.5	317628.5

Stress area: 2809.0 mm² · Proof load: 2,724,730 N · Clamp load (75%): 2,043,548 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	26157.4	19292.7	231512.6	266732.2
Oiled	0.15	19618.1	14469.6	173634.9	200049.7
Zinc Plated	0.18	23541.7	17363.5	208361.7	240059.4
Waxed	0.1	13078.7	9646.4	115756.3	133366.1
MoS₂	0.12	15694.4	11575.6	138907.2	160038.9
Galvanized	0.25	32696.8	24115.9	289391.2	333415.8

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 970 MPa × 2676.0 mm² = 1,946,790 N

Step 2 — Torque (dry): T = 0.20 × 0.0640 m × 1,946,790 N = 24918.9 N·m

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

Socket head cap screws, racing/motorsport, aerospace, maximum strength applications — highest standard 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.

SizeM64

Class12.9

Diameter64 mm

Pitch (coarse)6.0 mm

Tensile1220 MPa

Yield1100 MPa

Proof970 MPa