The stainless steel is a steel alloy with a minimum of 11% chromium by weight. It is highly resistant to attack by oxygen and other oxidizing agents under normal use. Other elements can be added, improving many properties.

The STAINLESS STEEL can be grouped in 3 families:

1 - Austenitic Steel(Tp 304, 304L, 316, 316L etc).

They are mainly composed of iron + chromium + nickel leagues.

Properties:

• High resistance to corrosion;
• They aren’t hardenable by fast coolness from high temperature, however hardenable by cold work;
  
• High durability;
• Not magnetic (after conformations can present some magnetic sensitivity);
• Used for cryogenic applications (works at high and low temperatures), due to
  good resistance to oxidation and softening in high temperatures;
  
• In the heating above 600ºC of AISI 304 material the steel with low carbon texts
  (304L and 316L) are indicated due its trend to corrosion in the grain contour;
  
• They are weldable by many processes.

2 - Ferritic Steel (Tp 409,410S, 430, etc).

They are mainly composed of iron + chromium leagues.

Properties:

• Magnetic;
  
• They are not hardenable by hardeness-state (maraging transformations);
• They can be pierced, cut, folded etc;
• High resistance to corrosion (specially under tension);
• Weldable (it requires special cares);
• Care in the reheating to other temperatures must be taken, because grain refinement
  does not occur under thermal treatment.

3 - Martensitic Steel (Tp 410, 420, 498, etc).

They are mainly composed by iron + chromium leagues, and having a higher carbon text than ferritic’s.

Properties: