Nickel is an alloying element that stabilizes austenite in steel. Because of the high manganese content in high manganese steels, the role of manganese stabilizing austenite often masks the role of nickel in the addition of high manganese steels. Nickel plays a major role in high manganese steels. as follows:
1) Nickel can inhibit the desolubilization of carbon from austenite, reduce the precipitation tendency of grain boundary carbides, and significantly reduce the amount of intergranular carbides. The nickel-containing high-manganese steel can be quenched instead of water to obtain a single austenite structure, which will greatly reduce the casting deformation and cracking rate caused by water quenching and simplify the production equipment.
2) Nickel can significantly improve the low temperature mechanical properties of high manganese steel. The impact toughness of 1% C-12% Mn high manganese steel at -40Â°C is only 57% of the room temperature, and after adding 3% of nickel, the ratio is increased to 75%. The zero plastic transition temperature (NDTT) of conventional high-manganese steel is -93Â°C. After nickel is added, it can be reduced below -100Â°C. When the nickel content is below 5%, the low temperature impact toughness of high manganese steel increases with nickel content. And improve.
3) Nickel can increase the use temperature of high manganese steel and expand the scope of application. After heating the ordinary high-manganese steel to 260 Â°C, it began to precipitate acicular carbides in the austenite manager, resulting in a corresponding increase in the brittleness of the material. The addition of 3% Ni to the high manganese steel can increase the precipitation temperature of the carbides to 380 Â°C.
4) Nickel can improve the oxidation resistance of high manganese steels. In the as-cast microstructure of nickel-containing high-manganese steel, the carbide size is small and the number is small. The austenitizing temperature can be reduced to about 950Â° C., and the holding time can be shortened accordingly. Since the nickel-containing casting itself has a good anti-oxidation effect, The amount of decarburization and scale generation after heat treatment of nickel-containing high-manganese steel castings was greatly reduced, and the quality of castings was significantly improved. In addition, nickel-containing high manganese steel also has good crack resistance.
5) Nickel can improve the welding performance of high manganese steel. Nickel-containing high manganese steel electrodes with chemical compositions (mass fraction) â‰¤ 1.1% C, 11%-18% Mn, 3.0%-5.0% Ni, 0.04%-0.06% Si, and â‰¤ 2.0% Mo can be used instead of 1Cr18Ni9Ti stainless steel electrodes Welding of high-manganese steel castings can achieve no carbide precipitation, no occurrence of austenite grain growth resulting in coarse columnar grain welds, good mechanical properties, strength, plasticity and toughness and ordinary high manganese steel no difference. Nickel is a shortage of resources in our country and its price is high. It should be used with caution in high manganese steels.
NJSB series analyzer can quickly detect Ni content in high manganese steel, stainless steel and other materials, accurate to 0.0001%
Nanjing Ningbo Analysis Instrument Co., Ltd. Technical Department