||Medium hardening rate, suitable for general cold processing and stretching, cold processing performance is good, commonly used for external hexagonal bolts, nuts and gaskets products.
||Adding molybdenum, corrosion resistance is better than 304, especially suitable for seawater and chemical media, more corrosion resistance and pitting resistance.
Stainless steel is short for stainless acid-resistant steel. Weak corrosive media such as air, steam, water or stainless steel are called stainless steel, while chemical corrosive media such as acid, alkali and salt are called acid-resistant steel.
Because of the difference in chemical composition between them, their corrosion resistance is different. Common stainless steel is generally not resistant to chemical medium corrosion, while acid-resistant steel is generally stainless. The term "stainless steel" refers not only to one kind of stainless steel, but also to more than one hundred industrial stainless steels. Each stainless steel developed has good properties in its specific application fields. The key to success is first to understand the use, and then to determine the correct steel grade. There are usually only six types of steel related to the application of building structures. They all contain 17-22% chromium and nickel in better steel grades. Addition of molybdenum can further improve atmospheric corrosion, especially resistance to chloride-containing atmospheric corrosion.
Stainless steel refers to steel which is resistant to weak corrosive media such as air, steam, water and chemical corrosive media such as acid, alkali and salt, also known as stainless steel. In practical application, steel resistant to weak corrosion medium is often called stainless steel, while steel resistant to chemical corrosion medium is called acid-resistant steel. Because of the difference in chemical composition, the former is not necessarily resistant to chemical medium corrosion, while the latter is generally stainless. The corrosion resistance of stainless steel depends on the alloying elements contained in the steel.
Structural Composition: The corrosion resistance of stainless steel decreases with the increase of carbon content. Therefore, the carbon content of most stainless steels is low, up to 1.2%, and that of some steels is even lower than 0.03% (e.g. 00Cr12). The main alloying element in stainless steel is chromium. Only when the content of chromium reaches a certain value, the steel has corrosion resistance. Therefore, the general content of Cr (chromium) in stainless steel is at least 10.5%. The stainless steel also contains Ni, Ti, Mn, N, Nb, Mo, Si, Cu and other elements.
COMPARISON WITH CARBON STEEL
The density of carbon steel is slightly higher than that of ferrite and martensite stainless steel, but slightly lower than that of austenitic stainless steel.
The resistivity increases in order of carbon steel, ferrite, martensite and austenitic stainless steel.
3. The order of linear expansion coefficient is similar. Austenitic stainless steel is the highest while carbon steel is the smallest.
4. Carbon steel, ferritic stainless steel and martensitic stainless steel have magnetism, while austenitic stainless steel has no magnetism, but it will produce magnetism when martensitic transformation occurs during cold work hardening. Heat treatment can be used to eliminate the martensitic structure and restore its nonmagnetism.
Compared with carbon steel, austenitic stainless steel has the following characteristics:
1) High resistivity, about 5 times that of carbon steel.
2) Large linear expansion coefficient is 40% larger than that of carbon steel, and with the increase of temperature, the value of linear expansion coefficient increases accordingly.
3) Low thermal conductivity is about 1/3 of that of carbon steel.