METRIC BOLT GRADES CHART

Metric Bolt Grades according to ISO 898 standard for carbon steel and alloy steel with property classes designations of 4.6, 4.8, 5.8, 8.8, 9.8, 10.9 and 12.9.

Metric Bolt Grades Chart
Mechanical or physical property Property class
4.6 4.8 5.6 5.8 6.8 8.8 9.8 10.9 12.9
d≤16 mm d>16mm
Minimum
tensile
strength,
MPa
400 420 500 520 600 800 830 900 1040 1220
Minimum
stress
at 0,2 %
nonproportional
elongation,
MPa
- - - - - 640 660 720 940 1100
Nominal
stress
under
proof load,
MPa
225 310 280 380 440 580 600 650 830 970
 

Reference:

  • ISO 898-1:2013– Mechanical properties of fasteners made of carbon steel and alloy steel Part 1: Bolts, screws and studs with specified property classes – Coarse thread and fine pitch thread