Hex Head Cap Screws Stainless steel is a remarkable and versatile material with many applications. Stainless steel differs from carbon steel by the amount of chromium present. Despite many different alloys and applications, stainless steel is a very common alloy used in industrial applications. Call Lightning Bolt & Supply for stainless bolts, nuts, washers, and even specials. Hex cap screws are headed fasteners with external machine screw threads. They are used to fasten two or more parts together and allow for maintenance and repair disassembly.