Hex bolts have a hexagonal head, are partially threaded and are used in machinery and construction applications. You can find out more in our complete guide to hex bolts.UsesThey can be used with a nut or in a tapped hole and are tightened with a hex key or wrench.Hexagon bolts are suitable for heavy duty fastening applications such as on bridges, buildings and road structures.Materials used for Hex BoltsBrass is a copper alloy which is more expensive than steel. It gives a better level of corrosion resistance.Stainless Steel gives good corrosion resistance and can be used outdoors. There are two different types of stainless steel: A4 (316) has a higher corrosion resistance than A2 (304). Both grades can handle low and high temperatures.Steel comes in different grade and strengths. A higher number indicates a stronger, more hardened material.Zinc Plated Steel is used on bolts for indoor use and gives a moderate corrosion resistance.