Stainless steel

The material. Stainless steels are alloys of iron with chromium, nickel, and often four or five other elements. The alloying transmutes plain carbon steel that rusts and is prone to brittleness below room temperature into a material that does neither. Indeed, most stainless steels resist corrosion in most normal environments, and those that are austenitic (like AISI 302, 304, and 316) remain ductile to the lowest of temperatures.

Composition

Fe/ < 0.25C/16-30Cr/3.5-37Ni/ < General properties

Density

Price

Mechanical properties

Young’s modulus

Yield strength (elastic limit)

Tensile strength Elongation Hardness—Vickers Fatigue strength at 107 cycles Fracture toughness

Thermal properties

Melting point

Maximum service temperature Thermal conductor or insulator? Thermal conductivity Specific heat capacity Thermal expansion coefficient

Electrical properties

Electrical conductor or insulator? Electrical resistivity

On the left: siemens toaster in brushed austenitic stainless steel (by Porsche Design). On the right, scissors in ferritic stainless steel; it is magnetic, whereas austenitic stainless is not.

Ecoproperties: material

Annual world production

30 X 106

– 3.1 X 106

tonne/yr

Reserves

*2.5 X 109

– 2.6 X 109

tonne

Embodied energy, primary production

*77

– 85

MJ/kg

CO2 footprint, primary production

*4.7

– 5.4

kg/kg

Water usage

*112

– 336

l/kg

Eco-indicator

860

– 960

millipoints/kg

Ecoproperties: processing

Casting energy

*3.9

– 4.4

MJ/kg

Casting CO2 footprint

*0.24

– 0.29

kg/kg

Deformation processing energy

*3.0

– 3.7

MJ/kg

Deformation processing CO2 footprint

*0.26

– 0.31

kg/kg

Recycling

Embodied energy, recycling

*22

– 24

MJ/kg

CO2 footprint, recycling

*1.4

– 1.5

kg/kg

Recycle fraction in current supply

35

– 40

%

Typical uses. Railway cars, trucks, trailers, food-processing equipment, sinks, stoves, cooking utensils, cutlery, flatware, scissors and knives, archi­tectural metalwork, laundry equipment, chemical-processing equipment, jet – engine parts, surgical tools, furnace and boiler components, oil-burner parts, petroleum-processing equipment, dairy equipment, heat-treating equipment, automotive trim. Structural uses in corrosive environments, e. g., nuclear plants, ships, offshore oil installations, underwater cables, and pipes.