Stainless steel rods can be divided into stainless steel black rods, stainless steel grinding rods, and stainless steel smooth circles according to their surfaces. An important element that makes up stainless steel is nickel. The role of nickel in stainless steel comes into play only after it is combined with chromium.

Nickel is an excellent corrosion-resistant material and an important alloying element in alloy steel. Nickel is an austenite-forming element in steel, but in order to obtain a pure austenite structure for low-carbon nickel steel, the nickel content must reach 24%; and only when the nickel content is 27% does the steel's resistance to certain media Corrosion properties change significantly. So nickel alone cannot constitute stainless steel. However, when nickel and chromium exist in stainless steel at the same time, nickel-containing stainless steel has many valuable properties.

Based on the above situation, it can be seen that the role of nickel as an alloy element in stainless steel is that it changes the structure of high-chromium steel, thereby improving the corrosion resistance and process performance of stainless steel.

Although chromium-nickel austenitic steel has many advantages, in recent decades, due to the large-scale development and application of nickel-based heat-resistant alloys and heat-strength steels containing less than 20% nickel, as well as the increasing development of the chemical industry, the demand for stainless steel has increased. However, the mineral reserves of nickel are small and concentrated in a few areas. Therefore, there is a contradiction between the supply and demand of nickel around the world. Therefore, in the fields of stainless steel and many other alloys (such as steel for large castings and forgings, tool steel, heat-strength steel, etc.), especially in countries where nickel resources are relatively scarce, the science of saving nickel and substituting nickel with other elements has been widely carried out. Research and production practice, in this regard, the most researched and applied method is to use manganese and nitrogen to replace nickel in stainless steel and heat-resistant steel.

Manganese has a similar effect on austenite as nickel. But to be more precise, the role of manganese is not to form austenite, but to reduce the critical quenching speed of steel, increase the stability of austenite during cooling, inhibit the decomposition of austenite, and prevent the formation of austenite at high temperatures. Austenite is maintained at room temperature. In terms of improving the corrosion resistance of steel, manganese has little effect. For example, if the manganese content in steel changes from 0 to 10.4%, it will not significantly change the corrosion resistance of steel in air and acid. This is because manganese has little effect on increasing the electrode potential of iron-based solid solution, and the protective effect of the oxide film formed is also very low. Therefore, although there are austenitic steels alloyed with manganese in industry (such as 40Mn18Cr4, 50Mn18Cr4WN, ZGMn13 steel etc.), but they cannot be used as stainless steel.

The role of manganese in stabilizing austenite in steel is about one-half that of nickel. That is, 2% of nitrogen can also stabilize austenite in steel, and its role is greater than that of nickel. For example, in order to make steel containing 18% chromium obtain an austenite structure at room temperature, low-nickel stainless steel with manganese and nitrogen substituted for nickel and chromium-manganese-nitrogen stainless steel with elemental nickel are currently used in industry, and some Has successfully replaced the classic 18-8 chromium-nickel stainless steel.