321 stainless steel is austenitic stainless steel,keep same with domestic grade 0Cr18Ni10Ti 321 stainless steel(Ni-Cr-Mo) type austenitic stainless steel. Due to the addition of element titanium, it has better”grain boundary corrosion resistance”and “high temperature strength”. The formation of chromium carbide is effectively controlled by adding titanium metal. It has good corrosion resistance in the atmosphere and is widely used in petrochemical, electric power, bridge and automobile industries. 

201 stainless steel is austenitic stainless steel, 201 stainless steel With"acid"and "alkali resistance"and"high density", "no bubbles", "no pinhole polishing"etc.201 and 202 is used for to make "watch case", "watch band bottom with best quality"etc.It’s mostly used for make " tubes", This is the main usage of 201 grade.Also,used for building decoration.