201 stainless steel has the characteristics of certain acid and alkali resistance, high density, no bubbles and no pinholes in polishing. Mainly used for decorative pipes, industrial pipes, and some shallow-stretched products. So, how did 201 stainless steel appear?
200 series stainless steel was first developed successfully in the United States as a substitute for 300 series stainless steel during World War II. At that time, due to the war, nickel as a strategic material was strictly controlled by the relevant countries, and the supply of nickel in the United States was seriously insufficient. In order to solve the production and supply problems of stainless steel in the case of a serious shortage of nickel supply, the United States has developed this new series of austenitic stainless steel with manganese instead of nickel.
After the end of World War II, the supply of nickel in the United States gradually improved. Therefore, the production of 300 series stainless steel is no longer restricted by the shortage of raw materials, so the 200 series has not been greatly developed. Several Indians who participated in the development of 200-series stainless steel at the beginning brought back to India the 200-series stainless steel developed in the United States, starting from the fact that India is relatively rich in manganese resources and lacking in nickel resources after returning to India.
The successful application of 200 series stainless steel in India is due to the possibility of replacing 304 stainless steel in some specific applications.
Most of the 200 series stainless steel sold in the Chinese market has little control of sulfur and carbon content in accordance with national standards, and replaces part or all of nickel with manganese (and nitrogen) to produce austenitic stainless steel with lower nickel content.
The disadvantage of this series of materials is that the chromium content below 18% and the low nickel content cannot reach a balance and form ferrite. For this reason, the chromium content in the 200 series stainless steel is reduced to 13.5% to 15%. Some The situation has dropped to 13% to 14%, and its corrosion resistance cannot be compared with 304 and other similar steels. In addition, manganese and in some cases copper reduce the effect of repassivation under acidic conditions common to corrosion sites in deposition zones and crevices. 200 series steel will fail at these conditions approximately 10-100 times faster than 304 stainless steel. Residual sulfur and carbon content in these steels are often not controlled in production, and the material cannot be traced back to its origin, even when the material is recycled. If Cr-Mn steels are not specified, they can be a dangerous mix of scrap, resulting in castings with unexpectedly high levels of manganese.