Typically there are two grades of stainless steel that Fasteners are produced in, the most common is stainless steel 304, which is typically known as A2 and 316 which is typically referred to as A4. Both grades of stainless steel offer excellent resistance from corrosion, especially in damp conditions and work well in both low and high temperatures.
Stainless steel grade 316 A4 is often used in marine environments, grade A4 has an increased resistance to chloride compared to 304 A2. The chemical formula for stainless steel A2 304 is : Carbon 0.08% - Manganese 2.00% - Phosphorus 0.045% - Sulfur 0.030% - Silicon 0.75% - Chromium 18-20% - Nickel 8-12% - Nitrogen 0.10% - Iron Balanced.
Fasteners are generally made from a 300 series austenitic stainless steel. Austenitic stainless steel has austentite (also known as gamma-phase iron y-Fe), as it is primary phase, as an alloy it generally contains both chromium and nickel and something nitrogen and molybdenum. Typically it is thought that stainless steel is non-magnetic, though that isn’t strictly true. More accurately the degree of magnetic response is derived from the microstructure of the steel. A totally non-magnetic material has a relative magnetic permeability of 1. In practice however this is rarely achieved, there is always a small amount of ferrite in the steel and so permeability values are always above one which makes it impossible for stainless steel to be “non-magnetic”.
Every day applications that stainless steel a preferred choice over steel zinc plated is because it doesn’t easily corrode, rust or stain from water where ordinary steel (even with a galvanised coating) can and will. The questions you would need to ask yourself when deciding which grade of stainless steel you require are generally,
1) Does the environment contain any; atmospheric conditions, water, chloride or is exposed to acid?
2) The higher the working temperature, the faster acceleration of corrosion and therefore indicates a higher grade required. Low temperature environments require a tough austensic steel (like stainless steel A2 & A4)
3) Higher strength can be obtained from the austenitic, duplex, martensitic and PH steels. Other processes such as welding and forming often influence which of these is most suitable. For example, high strength austenitic steels produced by work hardening would not be suitable where welding was necessary as the process would soften the steel.
Stainless steel is used in a wide and varied range of fasteners for applications and industries including automotive, train carriages, aircraft, jewellery and dentistry.
Stainless steel is 100% recyclable.
Metro Fixings stock a number of products in both stainless steel A2 and A4 which are listed below.
***CLICK HERE TO SEE THE STAINLESS FASTENER SECTION***
Hexagonal Full Nuts are most common nut that is used in construction and assembly. Full Nuts are available in both grades A2 and A4 stainless steel.
Hexagonal Nyloc Insert Nuts are a hexagonal full nut with a nylon filled collar at its top end, when a screw or bolt reaches the collar the threads of the screw or bolt form a tight frictional fit, reducing movement between the nut and bolt. Nyloc nuts are available in both grades A2 and A4 stainless steel.
Hexagonal Lock Nuts are a basically a Hexagonal Full Nut with approximately half the width. Typical applications of the Lock Nut is often used when a nut needs to be locked into place without clamping against another object. Other application where they are used is when a standard Hexagonal Full Nut simply will not fit. Hexagonal Lock Nuts are available in both grades A2 and A4 stainless steel.
Dome Nuts are ideal for making a bolt or a stud end look both attractive and safe. Dome Nuts are available in both grade A2 and A4 stainless steel.
Form A, B, C, D, and G Flat Washers are one of the most popular washers used in assembly and construction. The differences in thickness’ and diameters can be seen HERE. All form sizes are available in both grades A2 and A4 stainless steel.
Mudguard Penny Washers have a larger outside diameter comparted to form A, B or C Flat Washers. They are ideal for spreading the load on tightened fasteners or fixings. Penny Washers are also called Repair Washers & Mudguard Washers. Penny Washers are available in both grades A2 and A4 stainless steel.
Hexagon Headed Bolts are generally part threaded from the tip of the shank to just under the midpoint of the shank. Hex Bolts are available in both grades A2 and A4 stainless steel.
Hexagon Headed Set Screws are a variation of the Hexagon Headed Bolt. Hex Sets are generally fully threaded from the tip of the shank to the underside of the head. Hex Sets are available in both grades A2 and A4 stainless steel.
Socket Cap Screws have a cylindrical head with a hexagon drive. Deep sockets and a small head diameter allow for close spacing and a smooth finish. Socket Cap Screws are available in both grades A2 and A4 stainless steel.
Countersunk Socket Screws have a countersunk flush finish with a hexagonal drive that allows for a high torque attractive finish. Countersunk Socket Screws are available in both grades A2 and A4 stainless steel.
Socket Button Screws have a low profile dome head with a hexagonal drive that is ideal for a high torque attractive finish. Socket Button Headed Screws are available in both grades A2 and A4 stainless steel.
Coach Screws are a hexagonal headed screw with a wood screw thread for insertion into timber or use with nylon plugs. Coach Screws are available in both grades A2 and A4 stainless steel.
Coach Bolts are dome headed with a square shank underneath the head. A Coach Bolt is also commonly known as Cup Square Hex or Carriage Bolts. Coach Bolts are available from Metro Fixings in grade A2 304 stainless steel.
Self Tapping Screws are also known as “self tappers”, available in a range of heads including Pan, Countersunk in a number of drives including recessed and slotted. Most head types are available in grades A2 and A4 stainless Steel.
Posted: 20th July 2023
Author: Metro Fixings
