Stainless Steels Classifications

Stainless steels are commonly grouped into martensitic stainless steels, ferritic stainless steels, austenitic stainless steels, duplex (ferritic-austenitic) stainless steels, and precipitation-hardening stainless steels

Stainless steels are in general grouped into

  • martensitic stainless steels
  • ferritic stainless steels
  • austenitic stainless steels
  • duplex (ferritic-austenitic) stainless steels
  • precipitation-hardening stainless steels

Alloying metallic elements added during the making of the steel increase corrosion resistance, hardness, or strength. The metals used most commonly as alloying elements in stainless steel include chromium, nickel, and molybdenum.

Stainless steels are available in the form of

  • plate
  • sheet
  • strip
  • foil
  • bar
  • wire
  • pipes
  • tubes

Stainless steels are a iron-based alloy containing at between 10.5% to 30% Cr. Stainless steel achieve its stainless characteristic through the formation of an invisible and adherent chromium-rich oxide surface film.

Other alloying elements added to improve the characteristics of the stainless steel include nickel, molybdenum, copper, titanium, aluminum, silicon, niobium, nitrogen, sulphur, and selenium.

Carbon is normally in amounts from 0.03% to more than 1.0% in some martensitic grades.

Selection of stainless steels are in general based on

  • corrosion resistance
  • fabrication characteristics
  • availability
  • mechanical properties for specific temperature ranges
  • product cost

Since stainless steel resists corrosion, maintains its strength at high temperatures, and is easily maintained, it is widely used in items such as automotive and food processing products, as well as medical and health equipment. The most common US grades of stainless steel are:

TYPE 304

The most commonly specified austenitic (chromium-nickel stainless class) stainless steel, accounting for more than half of the stainless steel produced in the world. This grade withstands ordinary corrosion in architecture, is durable in typical food processing environments, and resists most chemicals. Type 304 is available in virtually all product forms and finishes.

TYPE 316

Austenitic (chromium-nickel stainless class) stainless steel containing 2%-3% molybdenum (whereas 304 has none). The inclusion of molybdenum gives 316 greater resistance to various forms of deterioration.

TYPE 409

Ferritic (plain chromium stainless category) stainless steel suitable for high temperatures. This grade has the lowest chromium content of all stainless steels and thus is the least expensive.

TYPE 410

The most widely used martensitic (plain chromium stainless class with exceptional strength) stainless steel, featuring the high level of strength conferred by the martensitics. It is a low-cost, heat-treatable grade suitable for non-severe corrosion applications.

TYPE 430

The most widely used ferritic (plain chromium stainless category) stainless steel, offering general-purpose corrosion resistance, often in decorative applications.

AUSTENITIC STAINLESS STEELS
TYPEEquivalent UNS
201S20100
202S20200
205S20500
301S30100
302S30200
302BS30215
303S30300
303SeS30323
304S30400
304LS30403
302HQS30430
304NS30451
305S30500
308S30800
309S30900
309SS30908
310S31000
310SS31008
314S31400
316S31600
316LS31603
316FS31620
316NS31651
317S31700
317LS31703
317LMNS31726
321S32100
330NO8330
347S34700
348S34800
384S38400

FERRITIC STAINLESS STEELS
TYPEEquivalent UNS
405S40500
409S40900
429S42900
430S43000
430FS43020
430FSeS43023
434S43400
436S43600
442S44200
446S44600

MARTENSITIC STAINLESS STEELS
TYPEEquivalent UNS
403S40300
410S41000
414S41400
416S41600
416SeS41623
420S42000
420FS42020
422S42200
431S43100
440AS44002
440BS44003
440CS44004

Related Topics

  • Codes and Standards - Piping codes and standards - ASME, ANSI, ASTM, AGA, API, AWWA, BS, ISO, DIN and more..
  • Water Systems - Hot and cold water systems - design properties, capacities, sizing and more
  • Material Properties - Material properties - density, heat capacity, viscosity and more - for gases, fluids and solids

Related Documents

Search the Engineering ToolBox

- "the most efficient way to navigate the Engineering ToolBox!"

Engineering ToolBox - SketchUp Edition - Online 3D modeling!

3D Engineering ToolBox - draw and model technical applications

Engineering ToolBox - SketchUp Edition - add standard and customized parametric components - like flange beams, lumbers, piping and more - to your SketchUp model - enabled for use with the amazing, fun and free SketchUp Make and SketchUp Pro. Add from the Sketchup Extension Warehouse!

Translate the Engineering ToolBox!
About the Engineering ToolBox!

close