Ultra high strength bainitic fasteners are gaining significant attention in recent years due to their exceptional combination of strength and toughness. The unique bainitic microstructure is generated through controlled heat treatments which impart superior mechanical characteristics and making these fasteners suitable for demanding applications in industries such as automotive, aerospace, construction and industrial machinery.
Generally, 14.8 grade and above are classified as ultrahigh-strength fasteners. We have a standard covering up to 12.9 grade in ISO 898. There is no ISO standard available to talk about fastener grade properties above 12.9. However, VDA 235-205 and USCAR-IFI provide guidance for ultrahigh-strength fasteners.