Stainless steel is not a single specific material; it is a name given to a group of corrosion resistant steels normally containing at least 11% chromium and bearing additions of nickel, molybdenum, titanium, and niobium.
Their corrosion resistance is owed to a passive film of sub-microscopic thickness (130å) rich in chromium and oxygen. Their film instantly reforms when broken as long as there is a supply of oxygen available.
Chromium Gives corrosion resistance. Ferrite former.
Carbon Gives hardness. Powerful austenite former.
Nickel Gives ductility. Increases high temperature strength. Austenite former.
Manganese Combines with Sulphur to form mang/sulphides which are austenite formers.
Silicon Increases high temperature strength. Prevents carburisation. Ferrite former.
Molybdenum Increases corrosion resistance and high temperature strength.
Titanium and Columbium Stabilise.
Sulphur and Selenium Increase machinability. Lower ductility and corrosion resistance.
Nitrogen Powerful austenite former.
Copper Increases corrosion resistance for sulphuric applications. Austenite former.
The two standard grades of stainless steel utilised by Component Developments are:
304 (BS 1449:PART 2:1983) 1.4301 (BS EN 10088-1:1995)
An austenitic grade for general-purposes with good resistance to atmospheric corrosion and to many organic and inorganic chemicals.
316 (BS 1449:PART 2:1983) 1.4436 (BS EN 10088-1:1995)
An austenitic grade with good resistance to uniform corrosion, pitting and crevice corrosion.
Both grades have excellent formability, weldability and impact strength making them suitable for fabrication of products used as surface drainage and protection.
Density 7.9 kg/dm3 8.0 kg/dm3
Modulus of Elasticity 200 Gpa 200 Gpa
Thermal Expansion 16 10-6/°C 16 10-6/°C
Thermal Conductivity 15 W/m°C 15 W/m°C
Thermal Capacity 500 J/kg°C 500 J/kg°C
Electrical Resistivity 0.73 mWm 0.75 mWm
Magnetisability No No