GMW GMW25 PDF

This specification defines the mechanical and material requirements for externally threaded fasteners sized M39 and smaller. This specification is based on ISO 898-1. However, only property class described in this document shall be used.

Material Description. The fasteners applicable to this specification are formed from wire steel and heat treated by quench and tempering, as required by the property class. The chemical composition, internal cleanliness of the steel, mechanical properties, microstructure, and other physical properties are described in this document.

Symbols. Not applicable. 

Typical Applications. This specification applies to bolts, screws, SEMS (bolts with washer assembly), threaded plugs, and studs.

Remarks. 

GM does not allow new release of fasteners with property class 9.8. The properties listed are for reference for legacy parts only. 

Property class 12.9 fasteners shall be released only after consultation and approval from GM Fastener and Materials Engineers. Usage of property class 12.9 (underlined grade) is not permitted. 

The scope of ISO 898-1 does not include threaded plugs. For the purpose of this specification, a threaded plug can be considered a very short bolt.