Hexagon bolts DIN 931 partial thread 8.8

DIN 931 has been replaced by ISO 4014. They are interchangeable. The nominal dimensions have been expanded, and M7 has been added. The wrench widths have been changed for M10, M12, M14, and M22. The hardness classes 4.8 and 12.9 for steel have been added, and 9.8 has been omitted. The hardness class 80 for stainless steel has been added. Non-ferrous bolts have been removed.