M33 Grade 4.6 Torque Specification

Torque Values by Surface Condition

Stress area: 693.55 mm² · Proof load: 156,049 N · Clamp load (75%): 117,037 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	772.4	569.7	6836.3	7876.3
Oiled	0.15	579.3	427.3	5127.2	5907.2
Zinc Plated	0.18	695.2	512.8	6153.0	7089.1
Waxed	0.1	386.2	284.8	3418.2	3938.2
MoS₂	0.12	463.5	341.9	4102.3	4726.4
Galvanized	0.25	965.6	712.2	8546.3	9846.4

Stress area: 760.85 mm² · Proof load: 171,191 N · Clamp load (75%): 128,393 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	847.4	625.0	7500.1	8641.1
Oiled	0.15	635.5	468.7	5624.7	6480.3
Zinc Plated	0.18	762.7	562.5	6750.5	7777.4
Waxed	0.1	423.7	312.5	3750.1	4320.6
MoS₂	0.12	508.4	375.0	4499.7	5184.3
Galvanized	0.25	1059.2	781.2	9374.7	10800.9

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 225 MPa × 693.55 mm² = 117,037 N

Step 2 — Torque (dry): T = 0.20 × 0.0330 m × 117,037 N = 772.4 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.

SizeM33

Class4.6

Diameter33 mm

Pitch (coarse)3.5 mm

Tensile400 MPa

Yield240 MPa

Proof225 MPa