Stainless steel pipes can be divided into Cr series (400 series), Cr-Ni series (300 series), Cr-Mn-Ni series (200 series) and precipitation hardening series (600 series). 200 series - chromium - nickel - manganese austenitic stainless steel 300 series - chromium - nickel austenitic stainless steel.

 

301 - - - good ductility, used for moulding products. It can also be rapidly hardened by mechanical processing. Good weldability. The wear resistance and fatigue strength are better than 304 stainless steel.

 

302 - - - Corrosion resistance is the same as 304, because the carbon content is relatively high and therefore the strength is better.

 

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

 

304 - - - 18/8 stainless steel. GB is 0Cr18Ni9. 309 - has better temperature resistance than 304.

 

316 - - - Following 304, the second most widely used steel is mainly used in food industry, pharmaceutical industry and surgical equipment, adding molybdenum to obtain a special corrosion-resistant structure. Compared with 304 stainless steel pipe, it has better chloride corrosion resistance, so it is also used as "marine steel". SS316 is usually used in nuclear fuel recovery devices. Class 18/10 stainless steel pipes usually meet this application level.

 

Model 321 - Except that the addition of titanium reduces the risk of weld corrosion, other properties are similar to 304.

 

400 series - ferrite and martensitic stainless steel.

 

408 - Good heat resistance, weak corrosion resistance, 11% Cr, 8% Ni.

 

409 - The cheapest model (British and American), usually used for automobile exhaust pipes, is ferritic stainless steel (chromium steel).

 

410 - martensite (high strength chromium steel), good wear resistance, poor corrosion resistance.

 

416 - Adding sulphur improves the processability of the material.

 

420 -"Tool Grade" martensitic steel, similar to Brinell high chromium steel, the earliest stainless steel. It's also used for surgical knives and can be made very bright.

 

430 - Ferritic stainless steel for decorative purposes, such as automotive jewelry. Good formability, but poor temperature resistance and corrosion resistance.

 

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

 

500 series - heat resistant chromium alloy steel.

 

Series 600 - Martensite precipitation hardening stainless steel pipe.