1.1 This part of ISO 6157 establishes limits for various types of surface discontinuities on bolts, screws and studs for special requirements.
It applies to bolts, screws and studs with
nominal thread diameters 5 mm and larger;
product grades A and B;
nominal lenghts l ≤ 10d (or longer if specified);
property class 12.9;
property classes 8.8, 9.8 and 10.9 when specified in product standards or agreed between supplier and purchaser.
1.2 Where the permissible limits for surface discontinuities indicated in clause 3 occur, the minimum values for the mechanical and functional properties specified in ISO 898-1 should still be met.
When fatigue strength requirements are specified, the fatigue strength should not be lower than that obtained on bolts without defects taken from the same lot.
NOTE 1 The figures in clause 3 are examples only. They apply correspondingly also to other types of bolts, screws and studs.
NOTE 2 The individual figures show the surface discontinuities exaggerated in some cases for clarity.