Fe–Cr–Ni (±Mo, N, C)
ChemistryStainless steel is specified as Fe–Cr–Ni (±Mo, N, C). Density band ~8.0 g/cm³.
What holds Stainless steel together is not the nickname. Formula Fe–Cr–Ni (±Mo, N, C), density ~8.0 g/cm³.
Meters are atlas-relative. Grades are the SKUs buyers write.
Phases
Microstructure
OrderProcessing sets grain, crystallinity or fibre orientation — the reason two lots of Stainless steel can test differently.
Interfaces
SurfacesCoatings, oxide films, sizings or paper faces often decide weather and fire behaviour more than the bulk brochure.
Defects
FlawsInclusions, voids, knots, pinholes or residual stress start the failures that mill certificates do not list.
Grades
VariantsStainless steel is a family. Grade names below are the ones buyers actually write on RFQs.
Ageing
TimeMoisture, UV, creep, hydrogen or carbonation shift properties in service. Design to the aged state.
Relative meters
Strength74
Strength is an editorial 0–100 mark relative to the other 31 materials in this atlas — not a laboratory certificate.
Heat envelope76
Heat envelope is an editorial 0–100 mark relative to the other 31 materials in this atlas — not a laboratory certificate.
Fire behaviour86
Fire behaviour is an editorial 0–100 mark relative to the other 31 materials in this atlas — not a laboratory certificate.
Insulation10
Insulation is an editorial 0–100 mark relative to the other 31 materials in this atlas — not a laboratory certificate.
Workability70
Workability is an editorial 0–100 mark relative to the other 31 materials in this atlas — not a laboratory certificate.
Circularity68
Circularity is an editorial 0–100 mark relative to the other 31 materials in this atlas — not a laboratory certificate.
Grades
304 / 18-8
General austenitic.General austenitic.
316 / 316L
Mo + low C for welds and chlorides.Mo + low C for welds and chlorides.
430
Ferritic, cheaper, magnetic.Ferritic, cheaper, magnetic.
410 / 420
Martensitic cutlery.Martensitic cutlery.
2205 duplex
Offshore and tanks.Offshore and tanks.
Bonds
Primary bonding
Stainless steel holds together by metallic bonding.
Secondary forces
Hydrogen bonds, van der Waals stacks or grain-boundary cohesion set toughness and moisture uptake.
Composites & fills
Fillers, fibres, plasticisers or aggregates are part of the real product, not impurities.
Environment film
Oxides, chars, sizings or paints are the layer the world actually meets.
Change the grade, the coating or the moisture and you have a different material with the same English name.
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