Bolt steels used for steel structures

Bolts are used in a wide variety of fields including the automobile industry, the civil engineering and construction industry, and the machine industry. Therefore, bolt strength class and fastening method are all highly variable according to use location and purpose, Consequently, the optimum steel grade for the application concerned must be selected from carbon steels to alloy steels. Bolts for steel structures are standardized by 'Sets of high strength hexagon bolt. hexagon nut and plain washers for friction grip joints (JIS B 1186 by Japanese Standards Association)' and 'Sets of torshear type high strength bolt. hexagon nut and plain washers for structural joints (JSS II 09 by Society of Steel Construction of Japan)'. But their bolts are not specified about used materials, However, it is necessary for the materials to possess a lot of characteristics, example for toughness and ductility, corrosion resistance, fire resistance, delayed fracture resistance, according to the use condition. In this paper, high strength bolt steels for steel structures are mainly introduced about conventional bolt, hot dip galvanized bolt, fire resistance bolt, weathering bolt, stainless bolt, super high strength bolt.