M42 Grade 4.6 Torque Specification

Torque Values by Surface Condition

Stress area: 1120.9 mm² · Proof load: 252,203 N · Clamp load (75%): 189,152 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	1588.9	1171.9	14063.0	16202.3
Oiled	0.15	1191.7	879.0	10547.4	12152.0
Zinc Plated	0.18	1430.0	1054.7	12656.6	14582.0
Waxed	0.1	794.4	585.9	7031.0	8100.7
MoS₂	0.12	953.3	703.1	8437.4	9721.0
Galvanized	0.25	1986.1	1464.9	17578.5	20252.7

Stress area: 1205.7 mm² · Proof load: 271,282 N · Clamp load (75%): 203,462 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	1709.1	1260.6	15126.8	17428.0
Oiled	0.15	1281.8	945.4	11344.9	13070.8
Zinc Plated	0.18	1538.2	1134.5	13614.2	15685.3
Waxed	0.1	854.5	630.2	7563.0	8713.5
MoS₂	0.12	1025.4	756.3	9075.6	10456.2
Galvanized	0.25	2136.3	1575.7	18907.9	21784.3

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 225 MPa × 1120.9 mm² = 189,152 N

Step 2 — Torque (dry): T = 0.20 × 0.0420 m × 189,152 N = 1588.9 N·m

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

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.

SizeM42

Class4.6

Diameter42 mm

Pitch (coarse)4.5 mm

Tensile400 MPa

Yield240 MPa

Proof225 MPa