Designation system for tensile strength

The designation system for screw and stud property classes is shown in table 1. The x-coordinates give values for nominal tensile strength Rm in Newtons per square millimetre, while the y-coordinates give values for elongation after fracture Amin in per cent.

The tensile strength comprises two numbers:
- The first number specifies 1/100 of the nominal tensile strength in N/mm2 (see Rm in tensile strength requirements).
- The second number specifies 10 times the ratio between the lower proof stress (or the yield strength Rp0.2) and the nominal tensile strength Rm.

Multiplying these two numbers indicates 1/10 of the proof stress in Newtons per square millimetre.The lower proof stress ReL (or yield strength Rp0.2) and the minimum tensile strength Rm are equal to or greater than the nominal values. Table 1.

Note: Despite the fact that a large number of property classes are specified in this part of ISO 898, this does not mean that all classes are suitable for all products.Further information regarding the application of the specific property classes is given in the relevant product standards.For non-standardised products, it is advisable to follow the choices that have already been made for similar standardised products as closely as possible.

Source: ISO 898