M42 Grade 4.8 Torque Specification

Torque Values by Surface Condition

Stress area: 1120.9 mm² · Proof load: 347,479 N · Clamp load (75%): 260,609 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	2189.1	1614.6	19375.2	22322.7
Oiled	0.15	1641.8	1210.9	14531.2	16741.8
Zinc Plated	0.18	1970.2	1453.1	17437.7	20090.5
Waxed	0.1	1094.6	807.3	9688.0	11161.9
MoS₂	0.12	1313.5	968.8	11625.5	13394.0
Galvanized	0.25	2736.4	2018.3	24219.2	27903.6

Stress area: 1205.7 mm² · Proof load: 373,767 N · Clamp load (75%): 280,325 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	2354.7	1736.7	20840.9	24011.3
Oiled	0.15	1766.0	1302.5	15630.4	18008.3
Zinc Plated	0.18	2119.3	1563.1	18757.4	21610.9
Waxed	0.1	1177.4	868.4	10420.9	12006.2
MoS₂	0.12	1412.8	1042.0	12504.3	14406.6
Galvanized	0.25	2943.4	2170.9	26051.3	30014.4

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 310 MPa × 1120.9 mm² = 260,609 N

Step 2 — Torque (dry): T = 0.20 × 0.0420 m × 260,609 N = 2189.1 N·m

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

Light structural connections, furniture assembly, non-load-bearing joints

• 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

Class4.8

Diameter42 mm

Pitch (coarse)4.5 mm

Tensile420 MPa

Yield340 MPa

Proof310 MPa