200 series stainless steel tube products and 300 lines on the surface are similar, but the performance is very different, especially in the aspect of corrosion resistance, it is not suitable for highly corrosive environment. Last year, the global stainless steel output of 22800000 tons, of which 200 series stainless steel accounted for about 8%, 300 accounted for 68%, 400 accounted for 24%. The company 500000 tons of stainless steel production, about 70% to 200 lines, Ferritic and austenitic stainless steel accounted for only 30%.