Stainless steel classification

According to the processing method, stainless steel is divided into: steel for pressure processing and steel for cutting; according to the structure characteristics, it is divided into five types: austenite type, austenite-ferrite type, ferrite type, martensite type and precipitation hardening type .

Stainless steel rods have broad application prospects and are widely used in hardware kitchen utensils, shipbuilding, petrochemical, machinery, medicine, food, electric power, energy, construction and decoration, nuclear power, aerospace, military and other industries!. Equipment used in sea water, chemical, dye, paper, oxalic acid, fertilizer and other production equipment; food industry, facilities in coastal areas, ropes, CD rods, bolts, nuts.

According to the composition, it can be divided into Cr system (SUS400), Cr-Ni system (SUS300), Cr-Mn-Ni (SUS200) and precipitation hardening system (SUS600).

200 Series—Chromium-Nickel-Manganese Austenitic Stainless Steels

300 Series—Chromium-Nickel Austenitic Stainless Steels

301—Good ductility, used for forming products. Can also be machine speed hardened. Good weldability. Wear resistance and fatigue strength are better than 304 stainless steel.

302—The corrosion resistance is the same as that of 304, and the strength is better because of the relatively high carbon content.

303—By adding a small amount of sulfur and phosphorus to make it more machinable.

304—that is, 18/8 stainless steel. The GB grade is 06Cr19Ni10.

309—Better temperature resistance than 304.

316—After 304, the second most widely used steel grade is 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.

Model 321—Similar to 304 except that the risk of material weld corrosion is reduced due to the addition of titanium.

400 Series—Ferritic and Martensitic Stainless Steels

408—good heat resistance, weak corrosion resistance, 11% Cr, 8% Ni.

409—The cheapest model (British and American), usually used as an automobile exhaust pipe, is a ferritic stainless steel (chrome steel).

410—Martensitic (high-strength chromium steel), good wear resistance and poor corrosion resistance.

416—The addition of sulfur improves the processing properties of the material.

420 – “Knives grade” martensitic steel, similar to the earliest stainless steels such as high chromium brinell steels. It is also used for surgical knives and can be made very shiny.

430—Ferritic stainless steel, for decoration, such as for car accessories. Good formability, but poor temperature resistance and corrosion resistance.

440—high-strength cutting tool steel, with slightly higher carbon content, higher yield strength can be obtained after proper heat treatment, and the hardness can reach 58HRC, which belongs to the hardest stainless steel. The most common application example is “razor blades”. There are three commonly used models: 440A, 440B, 440C, and 440F (easy to process).

500 Series—Heat resistant chromium alloy steel.

600 Series—Martensitic precipitation-hardening stainless steels.

630—The most commonly used type of precipitation hardening stainless steel, usually also called 17-4; 17%Cr, 4%Ni.