M45 Grade 4.8 Torque Specification

Torque Values by Surface Condition

Stress area: 1306.09 mm² · Proof load: 404,888 N · Clamp load (75%): 303,666 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	2733.0	2015.8	24189.1	27868.9
Oiled	0.15	2049.7	1511.8	18141.4	20901.2
Zinc Plated	0.18	2459.7	1814.2	21770.2	25082.1
Waxed	0.1	1366.5	1007.9	12094.5	13934.5
MoS₂	0.12	1639.8	1209.5	14513.5	16721.4
Galvanized	0.25	3416.2	2519.7	30235.9	34835.7

Stress area: 1397.15 mm² · Proof load: 433,116 N · Clamp load (75%): 324,837 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	2923.5	2156.3	25875.2	29811.5
Oiled	0.15	2192.7	1617.3	19407.0	22359.4
Zinc Plated	0.18	2631.2	1940.7	23288.1	26830.9
Waxed	0.1	1461.8	1078.2	12938.0	14906.3
MoS₂	0.12	1754.1	1293.8	15525.1	17886.9
Galvanized	0.25	3654.4	2695.3	32344.2	37264.6

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 310 MPa × 1306.09 mm² = 303,666 N

Step 2 — Torque (dry): T = 0.20 × 0.0450 m × 303,666 N = 2733.0 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.

SizeM45

Class4.8

Diameter45 mm

Pitch (coarse)4.5 mm

Tensile420 MPa

Yield340 MPa

Proof310 MPa