Stainless Steel "The Basics"
- The most important alloying element that makes stainless steels "Stainless" is Chromium.
- When at least 11% Cr is present, a continuous layer of an invisible oxide will form, which is what gives stainless steels their superior corrosion resistance.
- Nickel is the most commonly talked about element in stainless steels, due to the effect on price. The main role of Nickel in 200 and 300 series grades is to help create an austenitic structure which provides favorable mechanical properties.
Type 201LN Stainless:
This alloy is very comparable to type 304 in many respects, but they can provide some advantages over type 304 in certain applications.
- Resistance to corrosion comparable to type 304.
- Good resistance to oxidation.
- Ease of fabrication. High elongation permits bending and forming.
- Lower cost manganese and nitrogen are added as partial substitutes for nickel. Providing a lower more stable cost.
- Same physical appearance as type 304 stainless.
- Superior mechanical strength compared to type 304 stainless.
- The higher strength of type 201LN may permit weight reduction through the use of thinner material.
- Increased hardness over type 304 Stainless.
- Excellent toughness especially at low temperatures. Yield and Tensile strengths increase as temperature decreases.
- If type 304 is working satisfactorily in an application, the substitution of 201LN should be considered.
- Alloy is non-magnetic.
- Readily available in sheet and plate forms. No structural availability at this time.
Type 201LN stainless has been available for over 40 years and has gained acceptance in a number of applications.
This alloy is used extensively in the transportation industry for Dump bodies, truck trailer components and railroad cars as well as cryogenic tanks and vessels.
Finishes: (Only 2B and #4 finishes are available at Williamsen)
- HRAP –Is a hot rolled annealed and descaled product resulting in a dull rough surface. It is available in plate and sheet and is used for functional applications where a smooth decorative finish is not important.
- 2B – A smooth, moderately reflective cold-rolled annealed and pickled or descaled finish typically produced by imparting a final light cold-rolled pass using polished rolls. This general purpose finish is more readily polished than a HRAP finish product.
- #3 Polished Finish – A linear texture finish that may be produced by either mechanical polishing or rolling. Average surface roughness may be up to 45 micro inches.
- #4 Polished Finish – A linear texture finish that may be produced by either mechanical polishing or rolling. Average surface roughness may be up to 35 micro inches.