ISO 898-5:1998 pdf download – Mechanical properties of fasteners made of carbon steel and alloy steel
1 Scope
This part of ISO 898 specifies the mechanical properties of set screws and similar threaded fasteners not under tensile stresses with nominal thread diameters from 1,6 mm up to and including 24 mm, which are made of carbon steel or alloy steel.
The mechanical and physical properties apply when tested at an ambient temperature of 10 °C to 35 °C and will vary at higher or lower temperatures.
This part of ISO 898 does not apply to set screws requiring special properties such as
— specified tensile stresses (see ISO 898-1);
— weldability;
— corrosion resistance;
— ability to withstand temperatures above + 300 °C or below – 50 °C.
NOTE — Set screws made from free-cutting steel should not be used above + 250 °C.
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this part of ISO 898. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this part of ISO 898 are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards.
ISO 965-3:1998, ISO general purpose metric screw threads —Tolerances — Part 3: Deviations for constructional threads.
ISO 4948-1:1982, Steels — Classification — Part 1: Classification of steels into unalloyed and alloy steels based on chemical composition.
ISO 6506:1981, Metallic materials — Hardness test — Brinell test.
ISO 6507-1:1997, Metallic materials — Vickers hardness test — Part 1: Test method.
ISO 6508:1986, Metallic materials — Hardness test — Rockwell test (scales A – B – C – D – E – F – G – H – K).
6.1 Hardness tests
Hardness tests shall be conducted as near as practicable to the centre position of the point end of the screw. If the maximum hardness as given in table 3 is exceeded, a retest shall be conducted on a cross-section 0,5 d back from the point end where d is the nominal thread diameter. In case of doubt, the Vickers hardness test is decisive for acceptance. Hardness readings for the surface hardness shall be taken on the end of the screw, which will be prepared by slightly grinding or polishing to ensure reproducible readings.
6.2.1.1 base metal hardness: Hardness closest to the surface (when traversing from core to outside diameter) just before an increase or decrease occurs denoting carburization or decarburization.
6.2.1.2 decarburization: Generally, loss of carbon at the surface of commercial ferrous materials (steels).
6.2.1.3 partial decarburization: Decarburization with loss of carbon sufficient to cause a lighter shade of tempered martensite and significantly lower hardness than that of the adjacent base metal, however without showing ferrite grains under metallographic examination.
6.2.1.4 complete decarburization: Decarburization with sufficient carbon loss to show only clearly defined ferrite grains under metallographic examination.
6.2.1.5 carburization: Process of increasing surface carbon to a content above that of the base metal.