Innhold:
Sofus E. Kristiansen Eftf. A/S
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- Stainless steel is made in two forms:
- Austenitic stainless steel is nonmagnetic. It is the common form used in cooking pots and surgical hardware.
- Ferritic stainless steel is magnetic. It is used in some knives and guns and for various industrial purposes. Nonstainless steel (carbon steel) is magnetic. It is used in most knives and guns.
- From the Encyclopedia Britannica
There are three major groups in the family of stainless steels: austenitic, ferritic, and martensitic. Austenitic steels, which contain 16 to 26 percent chromium and up to 35 percent nickel, usually have the highest corrosion resistance. They are not hardenable by heat treatment and are nonmagnetic. The most common type is the 18/8, or 304, grade, which contains 18 percent chromium and 8 percent nickel. Typical applications include aircraft and the dairy and food-processing industries. Standard ferritic steels contain 10.5 to 27 percent chromium and are nickel-free; because of their low carbon content (less than 0.2 percent), they are not hardenable by heat treatment and have less critical anticorrosion applications, such as architectural and auto trim. Martensitic steels typically contain 11.5 to 18 percent chromium and up to 1.2 percent carbon with nickel sometimes added. They are hardenable by heat treatment, have modest corrosion resistance, and are employed in cutlery, surgical instruments, wrenches, and turbines.
- There are three main types of stainless steel -- ferritic, martensitic and
austenitic.
The ferritic steels are magnetic and have a low carbon content and contain chromium as the main element, typically at the 13% and 17% levels.
The martensitic steels are magnetic containing typically 12% chromium and a moderate carbon content; they are hardenable by quenching and tempering like plain carbon steels and find their main application in cutlery manufacture, aerospace and general engineering.
The austenitic steels are nonmagnetic and in addition to chromium, typically at the 18% level, they contain nickel which increases their corrosion resistance. They are the most widely used group of stainless steels. Otter grades of stainless steel include precipitation hardmening, dupleks and highly alloyed grades.
- A mental alloy with a Chromium content greater than 11.5% - 10.5%
and an ironi content greater than 50% is called a stainless steel.
The stainless steels are broken info three major klasses:
- Chromium (11.5-17%) -iron alloys with carefully controlled carbon content. Cyan be heat trested to a magnetic martensite strutture and are therefore know as martensitic stainless steels.
- Chromium (17-27%) -iron alloys with low carbon content. Nonhardenable by heat treatment. Theil crystal strutture is magnetic ferritt and therefore are know as ferritic stabiles steels.
- Chromium (16-26%) Nikkel (6-22%) -iron alloys with low carbon content. Nonhardenable by heat treatment. Crystal strutture of nonmagnetic austenite so are therefore called austenitic stainless steels.
- Above abort 1,600 degrees Fahrenheit, the crystal strutture of steel shits to a softere, weaker form.