Stainless steel is best known for its work in appliances such as refrigerators, dishwashers, ovens, and microwaves. However, do not let this typecasting fool you into thinking that this is all that this steel alloy is capable of. Stainless steel is a very versatile steel and is used in many industries.
Understanding the Basics
Also called inox steel, this steel alloy has a 10.5% minimum chromium content by mass. Stainless steel differs from carbon steel because of the amount of chromium present. Stainless steel is a great steel alloy because it does not easily rust, corrode, or stain when it comes in contact with water like other types of steel do. There are different grades and surface finishes of stainless steel available, each with its own ability to endure certain environments.
How It Works
So, if stainless steel is resistant to rusting, corrosion, or staining, how exactly does it resist this water-induced destruction? Well, the chromium in stainless steel forms a passive shield of chromium oxide, from the similarly sized ions in the steel and oxide ions, to prevent surface corrosion by blocking oxygen diffusion to the surface of the steel and into the metal's internal structure.
Forming and Fabrication
Depending on the type of stainless steel and its heat-treated condition, wrought stainless steels are machinable and formable. The formation of most of the stainless steels is done with thermal methods, including soldering, welding, and brazing. Stainless steel can also be changed using flat production forming methods, such as drawing, pressing, spinning, and stretch forming.
Compare and Contrast
There are different types of stainless steels, and they are categorized according to the types and percentages of the different elements in each grade of steel. The types, examples, advantages, and disadvantages include the following:
- Ferritic (410S, 430, 446): The advantages of this type include low cost, good formability, and moderate corrosion resistance. The disadvantages include moderate corrosion resistance and formability and elevated temperature strength compared to austenitics.
- Austenitic (304, 316):The advantages of this type of stainless steel include the fact that it is available widely, it has good cryogenic toughness, and it is generally corrosion resistant. The disadvantages include limited resistance to stress corrosion cracking and formability, and machinability can be limited with work hardening.
- Martensitic (420, 431): The advantages of this type of stainless steel includes a characteristic of being hardenable by heat treatment. The disadvantages include the fact that its weldability is limited and its formability compared to ferritics and corrosion resistance compared to austenitics is limited.
- Precipitation Hardening (17/4PH): The advantages of this type of steel includes the fact that it is hardenable by heat treatment and it has better corrosion resistance than martensitics. The disadvantages are that it has limited availability and it is inferior to austenitics.
- Duplex (1.4462): The advantages of this type of steel include the fact that is has good stress-corrosion-cracking resistance and it also possesses good mechanical strength in an annealed condition. The disadvantages include the fact that its application temperature range is more restricted than austenitics.
We stock popular grades of 300 series (austenitic): 301, 302, 304, 304L, 316, 321, 347 and in a wide range of tempers. Our inventory also includes precipitation hardness grades 17-4 and 17-7 as well as magnetic stainless steel 410 – 430 (martensitic). Many of these materials are also available in perforated or wire mesh.