Hex Head screws partial threaded ISO 4014-Duplex D6-100 M12x90 mm

Stainless steel refers to alloyed or unalloyed steels that contain at least 10.5% chromium and less than 1.2% carbon. Colloquially, stainless steel is also referred to as stainless steel (NiRo), although not all stainless steel is the same as "stainless".

The term plain indicates a completely untreated, merely oiled, smooth surface for all DIN and ISO screws such as wood screws, hexagon head screws, threaded rods, nuts and many types of washers.

The wrench sizes for hexagon bolts and nuts are specified in ISO 272: 1982-01. The nominal wrench size on the workpiece (e.g. bolt, nut) is the same as that on the tool. However, there is some play between the two to allow the tool to be fitted without difficulty. The relationship between the nominal diameter d of the thread and the wrench size s is standardised in EN ISO 4014 and EN ISO 4017 for hexagon bolts, and in EN ISO 4032 for hexagon nuts (dimensions in mm).

Steel screws with underhead ribs: These have a minimum tensile strength of 1000 N/mm² and are case-hardened (surface hardness of at least 550 HV) to ensure that the ribs or locking teeth can fulfil their function. This is a key difference from standard screws in accordance with DIN 6921. Stainless steel screws and nuts: The stainless steel nuts and screws are available in the following strength classes: (50), 70, 80 and 100.