Slotted grub screws with conical head DIN 551 / ISO 4766- stainless A1 M4x20 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.

Slotted screw drives are the oldest form of rotary drives for fastening screws. The Schltz is usually manufactured in a pressed or milled version. Because of its uneconomical processing method (slow, unwieldy), the slot is increasingly disappearing in favor of other drives (hexagon socket, cross slot, hexagon socket).

Grade 1.4305 is a sulphurised austenitic stainless steel of the A1 type. It is specifically intended for machining. Due to its high sulphur content of up to 0.35 per cent, this material has lower corrosion resistance than comparable stainless steels with a typical sulphur content of no more than 0.015 per cent. It is not suitable for use in non-oxidising acids and media or in chloride-containing environments (such as marine environments, etc.).

Hardness classes are specified for set screws and similar fasteners that are not subject to tensile stress, which are regulated for stainless austenitic steels in ISO 3506-3 and for carbon steel and alloy steel in ISO 898-5. ISO 3506-3 defines the two hardness classes 12H and 21H, ISO 898-5 defines the four hardness classes 14H, 22H, 33H and 45H. The hardness class designation 14H means 140 HV (Vickers hardness).

A1: This grade of steel is specifically intended for machining. Owing to their high sulphur content, steels of this grade have lower corrosion resistance than equivalent steels with a normal sulphur content.