The main effect of nickel in stainless steel is that it changed the crystal structure of steel. One of the main reasons for increase of nickel in stainless steel is the formation of austenite crystal structure, such as plasticity, thus improving the weldability and toughness properties of nickel stainless steel, so called austenitic forming element. Ordinary carbon steel crystal structure called a ferrite, a body-centered cubic (BCC) structure, the addition of nickel, the crystal structure from a body-centered cubic (BCC) structure into a face-centered cubic (FCC) structure, this structure called austenite. However, nickel is not the only element has the properties of. Common austenitic forming elements: nickel, carbon, nitrogen, manganese, copper. These elements in the formation of the relative importance of the crystal structure for the prediction of austenite stainless steel is important. At present, people have developed many formula to express the relative importance of austenite forming element,