300 Series—Chromium-Nickel Austenitic Stainless Steel
Model 301—good ductility, used for molded products. It can also be hardened by mechanical processing. Good weldability. Wear resistance and fatigue strength are better than 304 stainless steel.
Model 302 - The corrosion resistance is the same as 304, but the strength is better due to the relatively higher carbon content.
Model 303 - By adding a small amount of sulfur and phosphorus, it is easier to cut than 304.
Model 304—Universal model; i.e. 18/8 stainless steel. The GB grade is 0Cr18Ni9.
Model 309—has better temperature resistance than 304.
Type 316 - After 304, the second most widely used steel type, mainly used in the food industry and surgical equipment, the addition of molybdenum gives it a special structure that resists corrosion. 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 devices. Grade 18/10 stainless steel is also generally qualified for this application grade.
Model 321—Similar to 304 except that the addition of titanium reduces the risk of weld corrosion.
400 Series - Ferritic and Martensitic Stainless Steels
Model 408—Good heat resistance, weak corrosion resistance, 11% Cr, 8% Ni.
Model 409 - The cheapest model (British and American), commonly used as automotive exhaust pipes, ferritic stainless steel (chromium steel).
Model 410—Martensitic (high-strength chromium steel), good wear resistance, poor corrosion resistance.
Model 416—Added sulfur improves processing properties of the material.
Type 420—"Cutting grade" martensitic steel, similar to Brinell, the earliest stainless steel. Also used in surgical knives, which can be made very shiny.
Type 430—ferritic stainless steel for decorative purposes, such as automotive accessories. Good formability, but poor temperature resistance and corrosion resistance.
Model 440—high-strength cutting tool steel with slightly higher carbon content. After appropriate heat treatment, it can obtain higher yield strength and its hardness can reach 58HRC, which is among the hardest stainless steels. The most common application example is "razor blades". There are three commonly used models: 440A, 440B, 440C, and 440F (easy-to-process type).
500 Series—Heat-resistant chromium alloy steel.
600 Series—Martensitic precipitation hardening stainless steel.
Model 630—the most commonly used precipitation-hardened stainless steel model, usually also called 17-4; 17%Cr, 4%Ni.
