Surface Features & Manufacturing Methods & Applications of Stainless Steel Sheets

International labeling method for stainless steel plate

The American Iron and Steel Institute uses three digits to mark various standard grades of malleable stainless steel. in:

① Austenitic stainless steel is marked with numbers of 200 and 300 series. For example, some of the more common austenitic stainless steels are designated 201, 304, 316, and 310.

②Ferritic and martensitic stainless steels are represented by numbers in the 400 series. Ferritic stainless steels are marked with 430 and 446, and martensitic stainless steels are marked with 410, 420 and 440C.

③ Duplex (austenitic-ferritic) stainless steel, precipitation hardening stainless steel and high alloys with iron content less than 50% are usually named by patent names or trademarks.

Why does stainless steel have such strong corrosion resistance?

The corrosion resistance of stainless steel mainly depends on its alloy composition (chromium, nickel, titanium, silicon, aluminum, etc.) and internal structure, and the main role is chromium. Chromium has high chemical stability and can form a passivation film on the steel surface to isolate the metal from the outside world, protect the steel plate from oxidation, and increase the corrosion resistance of the steel plate. After the passivation film is destroyed, the corrosion resistance decreases.

300-600 type stainless steel brief description:

300 Series—Austenitic Stainless Steel

Model 301—Good ductility, used for forming 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, and the strength is better due to the relatively high carbon content.

Model 303—By adding a small amount of sulfur and phosphorus, it is easier to cut than 304.

Model 304—General model; ie 18/8 stainless steel. The GB grade is 0Cr18Ni9.

Model 309—better temperature resistance than 304.

Type 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". SUS316 is usually used in nuclear fuel recovery devices. 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

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

Model 409—The cheapest model (British and American), usually used for automobile exhaust pipes, is a ferritic stainless steel (chrome steel).

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

Type 416—addition of sulfur improves the machinability of the material.

Type 420—"Knives Grade" Martensitic Steel, the original stainless steel similar to Brinell High Chromium. It is also used for surgical knives and can be made very shiny.

Type 430—Ferritic stainless steel, decorative, eg for automotive trim. Good formability, but poor temperature resistance and corrosion resistance.

Model 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.

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

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Stainless Steel Plate 300 serious