DESCRIPTION

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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.

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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.

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COMPOSITION

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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.

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MATERIALS

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The two standard grades of stainless steel utilised by Component Developments are:

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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.

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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.

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Both grades have excellent formability, weldability and impact strength making them suitable for fabrication of products used as surface drainage and protection.

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PHYSICAL PROPERTIES

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                                                       304                             316

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