How to distinguish between steel and stainless steel
In daily life, we have more contact with austenitic stainless steel (some people called nickel stainless steel) and martensitic stainless steel (some people call it "stainless iron", but not scientific, easy to misunderstand, should avoid) two categories. Austenitic stainless steel is typically 0Cr18Ni9, i.e. "304" and "1Cr18Ni9Ti". Martensitic stainless steel for manufacturing stainless steel cutlery, brands include 2Cr13, 3Cr13, 6Cr13, 7Cr17 etc.. Due to differences in the two kinds of stainless steel components, the inner microstructure of the metal is not the same.
Made of stainless steel to the knife cut martensitic stainless steel. Because the knife has the function of shear items, must have the sharpness, want to have the sharpness must have a certain hardness. This kind of stainless steel must make its internal organizational change through heat treatment, the hardness increased to be knife cut. But the internal structure of this kind of stainless steel is tempered martensite, which has magnetic conductivity and can be attracted by magnet. Therefore, it is not simply possible to explain whether stainless steel is magnetic or not.
Austenitic stainless steel due to adding high chromium and nickel in steel (CR at about 18%, more than 4% in Ni), steel internal organization presents an organization called austenite state, this organization is not magnetic, can not be attracted by the magnet. Often used as decorative materials, such as stainless steel tubes, towel racks, tableware, stoves and so on.
In steel, chromium content of more than 12.5%, has a higher resistance to external media (acid, alkali, salt) corrosion of steel, known as stainless steel. According to the steel structure, stainless steel can be divided into Martensitic, Ferritic, Austenitic, Ferritic, Austenitic, precipitation hardening stainless steel, according to the provisions of the national standard GB3280 - 92, a total of 55 provisions.
Plain steel is carbon steel, or iron carbon alloy. According to the discretion of the carbon content, divided into low carbon steel (to say Shoutie), medium carbon steel and cast iron. Generally less than 0.2% carbon content is low carbon steel, commonly known as steel or pure iron; the contents of 0.2-1.7% in the name of steel; content of more than 1.7% is iron.
