1. What is austenitic stainless steel

     Austenitic stainless steel refers to stainless steel with austenitic structure at room temperature. When the steel contains about 18% Cr, 8%~25% Ni, and about 0.1% C, it has a stable austenite structure. Austenitic chromium-nickel stainless steel includes the famous 18Cr-8Ni steel and the high Cr-Ni series steel developed on the basis of increasing Cr and Ni content and adding Mo, Cu, Si, Nb, Ti and other elements. Austenitic stainless steel is non-magnetic and has high toughness and plasticity, but its strength is low. It is impossible to strengthen it through phase transformation. It can only be strengthened by cold working. If S, Ca, Se, Te and other elements are added, it has good properties. Machinability.

       2. What are the common austenitic stainless steels?

     There are more than 40 grades of austenitic stainless steel commonly used in China. It is mainly divided into the following two series:

1. 200 series: chromium-nickel-manganese austenitic stainless steel;

2. 300 series: chromium-nickel austenitic stainless steel:

(1) Model 301: Good ductility, used for molding products. It can also be hardened by mechanical processing. Good weldability. Wear resistance and fatigue strength are better than 304 stainless steel, products such as: springs, steel structures, wheel covers.

(2) Model 302: The corrosion resistance is the same as that of 304, and the strength is better due to the relatively high carbon content.

(3) Model 303: It is easier to cut than 304 by adding a small amount of sulfur and phosphorus.

(4) Model 304: General model; that is, 18/8 stainless steel. Products such as: corrosion-resistant containers, tableware, furniture, railings, medical equipment, some mobile phone frames. The standard composition is 18 % chromium plus 8 % nickel. It is a stainless steel that is non-magnetic and cannot change its metallographic structure by heat treatment.

(5) Model 304 L: Same characteristics as 304, but low carbon so it is more corrosion resistant and easy to heat treatment, but poor in mechanical properties. It is suitable for welding and products that are not easy to heat treatment.

(6) Model 304 N: It has the same characteristics as 304. It is a nitrogen-containing stainless steel. Nitrogen is added to increase the strength of the steel.

(7) Model 309: It has better temperature resistance than 304.

(8) Model 309 S: It has a large amount of chromium and nickel, so it has good heat resistance and oxidation resistance. Products such as: heat exchangers, boiler components, and jet engines.

(9) Model 310 S: Contains the most chromium and nickel, so it has the best heat resistance and oxidation resistance. Heat exchangers, boiler components, and electrical equipment.

(10) Model 316: After 304, the second most widely used steel grade, mainly used in the food industry and surgical equipment, adding molybdenum to obtain a special corrosion-resistant structure. Because it has better resistance to chloride corrosion than 304, it is also used as "marine steel". SS316 is usually used in nuclear fuel recovery units. Grade 18/10 stainless steel is also generally suitable for this application level. It is especially used in chemical, seaside and other corrosive environments, ship assembly, and building materials.

(11) Model 316 L: Low carbon, so it is more corrosion-resistant and easy to heat treatment. Products such as: chemical processing equipment, nuclear power generators, and refrigerant storage tanks.

(12) Model 321: Its performance is similar to 304 except that the risk of weld seam corrosion is reduced due to the addition of titanium elements. It is suitable for welding brewing equipment, steam pipes, and aviation parts.

(13) Model 347: Added stabilizing element niobium, suitable for welding aircraft parts and chemical equipment.