This standard specifies the test procedure for evaluating the acceptability of surface discontinuities designated in GB/T 5779.2 excluding nuts made of free cutting steel.
It applies to nuts with:
property classes to GB/T 3098.2 or GB/T 3098.4;
nominal thread diameter from 5mm up to and including 39mm;
product grades A and B.
2 Normative References
The following standards contain provisions which, through reference in this text, constitute provisions of this standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below.
GB/T 3098.2-2000 Mechanical Properties of Fasteners - Nuts - Coarse Thread (idt ISO 898-2: 1992)
GB/T 3098.4-2000 Mechanical Properties of Fasteners - Nuts - Fine Pitch Thread (idt ISO 898-6: 1996)
GB/T 3098.9-1993 Mechanical Properties of Fasteners - Prevailing Torque Type Steel Hexagon Nuts (eqv ISO 2320: 1983)
GB/T 5779.2-2000 Fasteners - Surface Discontinuities - Nuts (idt ISO 6157-2: 1995)
3 Widening Test
3.1 Principle
After removal of the thread up to the nominal thread diameter a tapered mandrel is pushed into the nut.
The widening is measured as a percentage of the hole diameter.
GB/T 3098.14-2000 The following standards are cited：
