All Stainless Steels can be divided into five categories:
- Austenitic
- Ferritic
- Martensitic
- Duplex
- Precipitation hardening
Key Facts about Stainless Steel
- Austenitic, Ferritic, and Martensitic account for over 90% of the stainless steels sold today.
- The term “Stainless Steel” is used for corrosion-resistant iron and chromium Alloys.
- A Stainless Steel must have a minimum Chromium content of 10.5%, the higher the Chromium content the better the corrosion resistance.
- A common misconception is that all Stainless Steels are non-magnetic, this is not the case, magnetism will vary from type to type and in some instances, even the method in which the raw material has been worked can affect the magnetism of the Stainless Steel in question.
- Dependent upon the environment and application, items made of Stainless Steel can last well over 100 years.
- Because all Stainless Steel is easily cleaned it is an ideal raw material for producing parts that have strict hygiene requirements such as Hospitals, Kitchens, and Food Processing plants.
- The name comes from the fact that Stainless Steel does not stain, corrode or rust as easily as ordinary steel.
- It is commonly believed that Harry Brearley who worked for the Brown-Firth research laboratory in Sheffield, England was the inventor of stainless steel. He first came across it while searching for a corrosion-resistant material for Gun Barrels in 1913.
AUSTENITIC |
FERRITIC |
MARTENSITIC |
DUPLEX |
PRECIPITATE HARDENED |
|
TYPICAL EXAMPLES |
201,301,302, 303, 304, 316 | 405, 430, 442 | 403, 410, 416 | 2205, Alloy 255 | 17-4PH, PH 17-7 |
ALSO KNOWN AS |
300 Serires 304=A2 or 18/8 316=A4 |
400 Series | 400 Series | N/A | N/A |
MAGNETISM |
Non-Magnetic * | Magnetic | Magnetic | Magnetic | Magnetic |
CORROSION RESISTANCE |
High | Moderate to High | Moderate | High | Moderate to High |
HIGH TEMPERATURE RESISTANCE |
High | High | Low | Low | Low |
DUCTILITY |
High | Moderate | Low | Moderate | Moderate |
WELDABILITY |
High | Low | Low | High | Low |
CAN IT BE HARDENED? |
Yes | No | Yes | Yes | Yes |
POPULARITY & TYPICAL APPLICATIONS |
Most common – Various industries & applications | Second most common – Various industries & applications | Common for cutlery, surgical instruments, scissors, and staples | Less common – Used in marine applications, etc. | Farily common in aerospace & engine components |
*Note: “Cold Working” (machining) can sometimes induce a slight magnetism.
Important: The above information is intended for guidance only.