The physical properties of 202 and the corresponding 300 series steel under solution treatment state, the physical properties of 200 series and 300 series are not much different, almost equivalent. However, the change of magnetic permeability after cold working is different. Due to the different degree of martensite induced during cold working, the increase of magnetic permeability is smaller than that of 200 series and 300 series.201 and 202 are different from other 200 series materials. Like 301 and 302, they belong to metastable austenitic stainless steel and have greater work hardening. These steel work hardening curves. 201 has similar hardening properties to 301 and 202 to 302. 201, 301 work hardening is larger. The amount of martensite generated varies for each grade. 202 and 304 martensite are very rarely generated, and work hardening mainly depends on deformity. For steels below 204 and 204L, work hardening almost depends on distortion. The mechanical properties and magnetic permeability of CrMnN series materials are shown in Table 5. The hardness of these steels in the solution treatment state is around HV250, and the strength after cold rolling is higher, and the Hv can reach 500, but the magnetic permeability is still lower than 1.005 in this state.
202 stainless steel pipe belongs to the 200 series, and the early development replaced nickel with manganese and nitrogen instead of 18-8 type chromium-nickel austenitic stainless steel. 18-8 type Cr-Ni stainless steel 301, 302, 304 (including 321) accounts for more than 50% of the total output of stainless steel. These steel grades have excellent comprehensive properties such as corrosion resistance, mechanical properties, high and low temperature properties, technological properties, and decorative properties, and are widely used in various fields from civil to military, as well as civil architectural decoration. Household appliances, kitchen equipment and utensils, transportation, environmental protection, municipal construction; military aviation, aerospace, nuclear industry, ships; industrial chemicals, fertilizers, petroleum, textiles, printing, paper, energy. Table 1 lists the AISI200 series of standard manganese-containing austenitic stainless steels. Therefore, 201, 202, 204, 205, and 206 were studied in the early days, that is, 301, 302, 304, 305, and 316 corresponding to the Cr-Ni system. Next, 211 was developed, and the steel grades with low carbon nitrogen, Mn and Cu were used for cold working. 201L, 201LN, etc. are improvements of 201 to solve the problem of intergranular stress corrosion.Used as the corresponding components of cars, trains and subway cars. Later developed S21400 (XM-31 ), S24000 (XM-29, Nitronic33 ), S28200 (Carpenter18-18plus), S21900 (XM-11, Nitronic40 ), S20910XM-19, Nitronic50 ) and YUS120 and other high-strength corrosion-resistant stainless steel . XM-31, XM-11 are used in aviation, cryogenic systems, without magnetic components. XM-11, XM-19, etc. have better corrosion resistance than 316, used in pumps, valves, fasteners, marine materials, heat exchangers, springs, etc.