20CrMnTi is a kind of low carbon alloy steel. The main alloying elements are chromium and manganese, and the amount of alloying elements is relatively small. The carbon content is less than 0.15%, the content of silicon, phosphorus and sulfur is low. 20CrMnTi has high strength and good hardenability. It is commonly used in the manufacture of automotive, agricultural machinery, construction machinery, fasteners and die materials.
Since 20CrMnTi alloy generally has a low carbon content and good hardness after quenching, carbon and alloy steels are usually subjected to carburizing treatment before quenching to increase the surface hardness and wear resistance of the steel. After carburizing treatment and quenching, the surface layer has high hardness, while the core layer has low hardness and good plasticity, which is very suitable for the processing of parts.
Microstructure (stable austenite + martensite) of 20CrMnTi steel after carburizing and quenching at 920℃: The surface structure of the steel is a layered structure composed of pearlite and martensite, and the metallographic structure of the core is uniformly composed of ferrite and pearlite. The alloy element has a great influence on the microstructure of 20CrMnTi steel. The rich alloy element makes the ferrite stronger than the pearlite, which affects the transformation of ferrite and pearlite and the dislocation structure of the matrix.
20CrMnTi steel is a kind of low carbon steel, so it is suitable for low temperature carburizing and quenching. The grain constituent of 20CrMnTi steel is composed of microbands of ferrite and pearlite. The microband structure of the surface layer is dense, which is beneficial to the improvement of wear resistance and fatigue strength of the parts. The place where the carbide particles precipitate is generally at the boundary of the microbands, which not only makes the martensite have a higher hardness at nicroabd boundary and has a certain wear resistance, but also improves the added value of the parts.
The biggest advantage of 20CrMnTi steel after carburizing and quenching at 920℃ is that a thin , hard and wear-resistant surface layer can be obtained, while the core is still soft and plastic. After carburizing, the surface layer is transformed from austenitic to martensitic structure, which can obtain higher hardness and wear resistance. Therefore, 20CrMnTi steel is widely used in the manufacture of parts which require high surface hardness, wear resistance and strength. In summary, 20CrMnTi steel after carburizing and quenching at 920℃ has good performance, which effectively solves the problem of low strength and poor wear resistance of some parts.
