Stainless Steel Guide

What is Stainless Steel?
Stainless steel is essentially a low carbon steel which contains chromium at 10% or more by weight. It is this addition of chromium that gives the steel its unique stainless, corrosion-resisting properties.

The chromium content of the steel allows the formation of a rough, adherent, invisible, corrosion-resisting chromium oxide film on the steel surface. If damaged mechanically or chemically, this film is self-healing, providing that oxygen, even in very small amounts, is present.

The corrosion resistance and other useful properties of the steel are enhanced by increased chromium content and the addition of other elements such as molybdenum, nickel, and nitrogen.

There are more than 60 grades of stainless steel. However, the entire group can be divided into five families. Each is identified by the alloying elements which affect its microstructure and for which each is named.
 

Specifications By Stainless Steel Grade
303
 
A non-magnetic stainless steel specially designed for improved machinability.
 
304
 
Chromium-Nickel austenitic alloy used in a wide range of applications.
 
304L
 
Chromium-Nickel austenitic alloy used in a wide range of applications.
 
316L
 
Molybdenum bearing austenitic stainless steels which are more resistant to general corrosion and pitting/crevice corrosion.
 
 
317L
 
Molybdenum bearing austenitic stainless steels with increased resistance to chemical attack compared to standard chromium-nickel austenitic stainless steels.
 
317LMN 317L +
 
Increased levels of moly and nitrogen for enhancing resistance to pitting and crevice corrosion.
 
 
304H
 
Modification of 304 in which the carbon content is controlled to a range of 0.04 – 0.10 to provide improved high temperature strength.
 
 
321/ 321H
 
A stabilized stainless steel which has excellent resistance to intergranular corrosion following exposure to temperatures in the chromium carbide precipitation range from 800 to 1500°F.
 
347/ 347H
 
Stabilized stainless steel which offers excellent resistance to intergranular corrosion following exposure to temperatures in the chromium precipitation range from 800 to 1500°F.
 
309/ 309S
 
Austenitic stainless steel used in applications where elevated temperatures are present.
 
 
310S
 
Austenitic stainless steel used in applications where elevated temperatures are present.
 
 
410
 
Hardenable, straight-chromium stainless steel which combines superior wear resistance with excellent corrosion resistance.
 
410S
 
Low carbon non-hardening modification of 410. Resists cracking when exposed to high temperatures or in the as-welded condition.
 
 
LDX2101
 
Low nickel lean duplex stainless steel possessing both superior strength and chloride stress-corrosion cracking resistance when compared to 300 series stainless steels.
 
2304
 
A high chromium-low nickel-moly free duplex stainless steel exhibiting improved strength and stress corrosion resistance properties compared to 304/316 austenitic stainless steels.
 
2205
 
A high chromium-nickel-moly duplex stainless steel providing high strength and superior resistance to general, local, and stress corrosion compared to 316L or 317L.
 
2507
 
A chromium-nickel-moly super duplex stainless steel with exceptional strength and corrosion resistance in the chemical process, petrochemical, and seawater environments.
 
17-4PH
 
Martensitic stainless steel that is capable of precipitation hardening. This stainless steel has very high strength and hardness.
 
 
SSC-6MO
 
Superaustenitic 6% molybdenum alloy that exhibits superior resistance to chloride pitting, crevice corrosion and stress-corrosion cracking when compared with the standard 300 series and duplex stainless steels. Premier corrosion resistant austenitic stainless steel.