M45 Grade 5.8 Torque Specification

Torque Values by Surface Condition

Stress area: 1306.09 mm² · Proof load: 496,314 N · Clamp load (75%): 372,236 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	3350.1	2470.9	29650.9	34161.6
Oiled	0.15	2512.6	1853.2	22238.4	25621.5
Zinc Plated	0.18	3015.1	2223.8	26685.9	30745.6
Waxed	0.1	1675.1	1235.5	14825.9	17081.3
MoS₂	0.12	2010.1	1482.6	17790.9	20497.4
Galvanized	0.25	4187.7	3088.7	37064.3	42702.8

Stress area: 1397.15 mm² · Proof load: 530,917 N · Clamp load (75%): 398,188 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	3583.7	2643.2	31718.4	36543.7
Oiled	0.15	2687.8	1982.4	23789.0	27408.0
Zinc Plated	0.18	3225.3	2378.9	28546.3	32889.0
Waxed	0.1	1791.8	1321.6	15858.8	18271.3
MoS₂	0.12	2150.2	1585.9	19030.9	21926.0
Galvanized	0.25	4479.6	3304.0	39647.8	45679.4

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 380 MPa × 1306.09 mm² = 372,236 N

Step 2 — Torque (dry): T = 0.20 × 0.0450 m × 372,236 N = 3350.1 N·m

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

General industrial fastening, equipment mounting, moderate structural loads

• 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.

SizeM45

Class5.8

Diameter45 mm

Pitch (coarse)4.5 mm

Tensile520 MPa

Yield420 MPa

Proof380 MPa