Ultimate Strength
8 x100 = 800MPa
Yield Strength or Stress at 0,2% permanent Set
8 x 8 x 10 = 640 MPa
Property class Designation for Nuts
The
corresponding code for nuts is a single number and is derived from the left
hand number of the property class of the bolt, screw and stud. This number
when multiplied by 100 indicates the Proof Load Stress of the nut in MPa.
Thus, for the bolt of property class 8,8 in the above example a nut of
property class 8 is required. This nut will have a Proof Load Stress of 8 x
100 = 800 MPa
In practice only standard threaded fasteners in the high tensile property
classes, i.e. property class 8,8 and above are required to be marked with
the appropriate code.
Property class Designation Marking of Bolts, Screws and Studs
Property class
3,6
3,6
4,6
4,8
5,8
6,6
6,8
8,8
10,9
12,9
14,9
Markings
3,6
3,6
4,6
4,8
5,8
6,6
6,8
8,8
10,9
12,9
14,9
Property class Designations of Steel Nuts
Property class
4
5
6
8
10
12
Proof Load Stress, MPa
400
500
600
800
1000
1200
Steel Bolts/ Screws/ Stud and Nut Combinations
Property class of Bolt
3,6
4,6
4,8
5,6
(5,8)
(6,6)
6,8
8,8
10,9
12,9
(14,9)
Recommended Property class Of Nut
4
4
4
5
5
6
6
8
10
12
14
Note: *Higher property class nuts may be used on lower property class bolts