M52 Grade 4.6 Torque Specification

Torque Values by Surface Condition

Stress area: 1757.73 mm² · Proof load: 395,489 N · Clamp load (75%): 296,617 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	3084.8	2275.2	27302.8	31456.3
Oiled	0.15	2313.6	1706.4	20477.1	23592.2
Zinc Plated	0.18	2776.3	2047.7	24572.3	28310.5
Waxed	0.1	1542.4	1137.6	13651.4	15728.2
MoS₂	0.12	1850.9	1365.2	16381.9	18874.0
Galvanized	0.25	3856.0	2844.0	34128.5	39320.4

Stress area: 1828.6 mm² · Proof load: 411,435 N · Clamp load (75%): 308,576 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	3209.2	2367.0	28403.8	32724.9
Oiled	0.15	2406.9	1775.2	21302.9	24543.6
Zinc Plated	0.18	2888.3	2130.3	25563.6	29452.6
Waxed	0.1	1604.6	1183.5	14201.9	16362.4
MoS₂	0.12	1925.5	1420.2	17042.1	19634.7
Galvanized	0.25	4011.5	2958.7	35504.8	40906.1

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 225 MPa × 1757.73 mm² = 296,617 N

Step 2 — Torque (dry): T = 0.20 × 0.0520 m × 296,617 N = 3084.8 N·m

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

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.

SizeM52

Class4.6

Diameter52 mm

Pitch (coarse)5.0 mm

Tensile400 MPa

Yield240 MPa

Proof225 MPa