Class 5.6 bolts are not very strong and they are flexible and forgable. therefore 5.6 bolts are only manufactured with Coarse Threads from M5 to M36
Hex nuts are manufactured according to varios standards suiting the bolt they connect with. Standard hex nuts are manufactured according to DIN934 standard. Stainless steel hex nuts and carbon steel hex nuts have wide use in industries.
Structural bolts are stronger than usual hex bolts even in equal tensile. structural bolts are commonly used in heavy construction sites including DAM and powerplant construction.