310S/S31008 - Stainless steel

As an important material in aerospace and chemical industry, 310S heat-resistant steel is widely used in High temperature environment. High-temperature oxidation is the most common and important form of corrosion damage at high temperatures, so the research and development of new materials with high-temperature oxidation resistance is of far-reaching significance for China's aviation industry, chemical industry and national defense [1]. Austenitic heat resistant Stainless Steel 310S(0Cr25N i20) is a high chromium-nickel austenitic stainless steel

The role of nickel in stainless steel is played after it is combined with chromium

1. Nickel is an excellent corrosion-resistant material and an important alloying element of alloy steel. Nickel is an element that forms austenite in steel, but the nickel content of low carbon nickel steel should reach 24% to obtain pure austenite structure. Only when the nickel content is 27%, the corrosion resistance of steel in some media changes significantly. Therefore, nickel cannot constitute stainless steel alone. 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 alloying element in stainless steel is that it makes the structure of high chromium steel change, so that the corrosion resistance and process performance of stainless steel can be improved.

2. Manganese and nitrogen can replace nickel in chrome-nickel stainless steel

Although the advantages of chromium-nickel austenitic steel are many, in recent decades due to the large number of 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 is growing, and the amount of nickel deposits is small and concentrated in a few areas, so there is a contradiction in the supply and demand of nickel worldwide. Therefore, in the fields of stainless steel and many other alloys (such as large casting and forging steel, tool steel, heat-strength steel, etc.), especially in countries where nickel resources are relatively lacking, scientific research and production practices have been widely carried out to save nickel and replace nickel with other elements. In this regard, more research and application are conducted to replace nickel in stainless steel and heat-resistant steel with manganese and nitrogen.

3. The effect of manganese on austenite is similar to nickel. But to be 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, so that the austenite formed at high temperature can be maintained to normal temperature. In terms of improving the corrosion resistance of steel, manganese has little effect, such as the change of manganese content in steel from 0 to 10.4%, and the corrosion resistance of steel in air and acid does not change significantly. This is because manganese has little effect on improving the electrode potential of iron-based solid solutions, and the protective effect of the oxide film formed is also very low, so although there are austenitic steels (such as 40Mn18Cr4,50Mn18Cr4WN, ZGMn13 steel, etc.) alloyed with manganese in industry, they cannot be used as stainless steel. The role of manganese in stabilizing austenite in steel is about half that of nickel, that is, 2% of nitrogen in steel is also stabilizing austenite, and the degree of effect is greater than nickel. For example, in order to make steel containing 18% chromium obtain austenitic structure at room temperature, low-nickel stainless steel with manganese and nickel nitrogen and nickel chromium manganese nitrogen non-inducer steel have been applied in industry, and some have successfully replaced the classic 18-8 chromium nickel stainless steel.