Introduction
High-manganese cast steel is a kind of low alloy cast steel with high strength, high toughness, good wear resistance and impact resistance after quenching and tempering. It is often used in situations of difficulty to heat treat steel or impact load and wear. At present, high-manganese cast steel is widely used in many fields, such as mining machinery, engineering machinery, agricultural machinery and automobile industry, etc.
Classification
High-manganese cast steel can be divided into three categories according to its chemical composition. The first is high manganese steel (usually referred to as Hadfield steel) with an alloy content of 12% to 14%. This kind of steel has high strength and toughness, and the cold-gypsum is large. It has good wear resistance and is suitable for making wear parts and components. The second category is low manganese steel with an alloy content of 8% to 12%. This kind of steel has high quenching hardness, low notch sensitivity and strong hardenability. It is mainly used for making rollers, shafts, gears and other parts. The third category is ultra-high manganese steel with an alloy content of 14% to 20%. This kind of steel has good ductility and toughness before and after quenching, which makes the cold-gypsum small, and it has good wear resistance and impact toughness. It is mainly used for making parts and components requiring large impact load.
Analysis on Chemical Composition of High-manganese Cast Steel
High-manganese cast steel contains mainly manganese(Mn), silicon(Si), carbon(C), phosphorus(P), sulfur(S), and traces of a few other alloying elements such as nickel(Ni), chromium(Cr),bismuth(Bi), tungsten(W), molybdenum(Mo), and vanadium(V).
Manganese(Mn): manganese is a very important alloying element in high-manganese cast steel. Above 12% Mn can form Mn7C3 carbide, which can increase the strength and toughness of steel. The tensile strength and yield strength of high-manganese cast steel increase with the increase of manganese content. Silicon(Si): Silicon and manganese are together called magnesium, which helps to improve the microstructure and strength of high-manganese cast steel. Its role is mainly to reduce the austenite transformation temperature.
Carbon(C): Carbon is a very important element for hardenability. For example, for a structure containing 0.2% of carbon, when the carbon has been increased to 0.4%, the hardenability will be increased by 50%. However, too much carbon will lead to a decrease in strength. Phosphorus(P): Phosphorus can form phosphide in high-manganese cast steel, making the microstructure finer and more uniform, so that it is beneficial to increase the strength and toughness of steel. In general, phosphorus content should not exceed 0.05%.
Sulfur(S): Sulfur can promote graphitization, reduce hot strength and improve machinability. In general, sulfur content should not exceed 0.04%.
Nickel(Ni), Chromium(Cr), Bismuth(Bi), Tungsten(W), Molybdenum(Mo), and Vanadium(V): Nickel, chromium, bismuth, tungsten, molybdenum and vanadium are secondary alloying elements in high-manganese cast steel. They mainly help to improve the strength, toughness and corrosion resistance of steel. In general, the content of each should not exceed 0.3%.
Conclusion
High-manganese cast steel is a kind of low alloy cast steel, which is mainly composed of manganese, silicon, carbon, phosphorus and sulfur, and traces of a few other alloying elements. Among them, manganese and silicon are called magnesium, which is important for the strength and toughness of steel. Carbon has a great influence on the hardenability of steel. Phosphorus can improve the strength and toughness of steel. Sulfur can reduce the hot strength and improve the machinability of steel. Other secondary alloying elements can help to improve the strength, toughness and corrosion resistance of steel.
