Hex head bolts DIN 931 are a type of threaded fastener with an external hexagonal head used in mechanical assemblies and structural connections. The hexagonal shape of the bolt head allows it to be easily tightened or loosened with a wrench or socket. These bolts are made to the DIN 931 international standard which specifies the exact dimensions, tolerances, and mechanical properties. They are available in a range of metric thread sizes like M8, M10, M12 etc. and have a course pitch thread for use in thicker materials.

The hex head has 6 flat sides that can be gripped by tools to provide torque when tightening the bolt. This prevents rounding off the head compared to fasteners with curved heads like slotted or phillips. The hex shape also allows for maximal contact between the tool and bolt head for efficient torque transfer. These bolts are extremely popular and used in many applications such as machinery, equipment, vehicles, structural steelwork, and anywhere a strong threaded fastener is required. They provide an excellent combination of usability, strength, and cost-effectiveness. Materials used for DIN 931 hex head bolts include low, medium, and high carbon steels for varying levels of strength. The DIN 931 standard ensures consistent quality across manufacturers and sourcing locations. Overall, these versatile hex head bolts are a staple component in mechanical assemblies and construction projects.