M56 Grade 4.6 Torque Specification

Torque Values by Surface Condition

Stress area: 2030.0 mm² · Proof load: 456,750 N · Clamp load (75%): 342,562 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	3836.7	2829.8	33957.7	39123.6
Oiled	0.15	2877.5	2122.3	25468.0	29342.4
Zinc Plated	0.18	3453.0	2546.8	30561.6	35210.9
Waxed	0.1	1918.4	1414.9	16979.3	19562.3
MoS₂	0.12	2302.0	1697.9	20374.4	23474.0
Galvanized	0.25	4795.9	3537.3	42447.3	48904.8

Stress area: 2120.0 mm² · Proof load: 477,000 N · Clamp load (75%): 357,750 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	4006.8	2955.3	35463.2	40858.1
Oiled	0.15	3005.1	2216.4	26597.4	30643.6
Zinc Plated	0.18	3606.1	2659.7	31916.7	36772.1
Waxed	0.1	2003.4	1477.6	17731.6	20429.1
MoS₂	0.12	2404.1	1773.2	21278.1	24515.1
Galvanized	0.25	5008.5	3694.1	44329.0	51072.7

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 225 MPa × 2030.0 mm² = 342,562 N

Step 2 — Torque (dry): T = 0.20 × 0.0560 m × 342,562 N = 3836.7 N·m

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

Non-critical assemblies, light-duty applications, general-purpose hardware where high strength is not required

• 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.

SizeM56

Class4.6

Diameter56 mm

Pitch (coarse)5.5 mm

Tensile400 MPa

Yield240 MPa

Proof225 MPa