Formation of Structure of Wear-Resistant Steels 150KhNML and Kh12MFL Upon Quenching
Quenching is a common thermal treatment used to rapidly cool a steel from a high temperature to below its critical temperature. The main purpose of quenching is to obtain a specific microstructure in the steel, including a very fine ferrite grains, as well as to improve its wear and/or physical properties. On the other hand, quenching can also be used to impart wear-resistant properties to steels. In the case of wear-resistant steels 150KhNML and Kh12MFL, quenching is used to promote the formation of a fine and homogenous distribution of small particles, mainly of carbides, nitrides, and carbonitrides, in the steel microstructure. This gives great wear resistance to these steels.
Shows the microstructure of 150KhNML upon quenching. It can be seen that the microstructure consists mainly of very fine pearlite (white) surrounded by ferrite (grey). In addition, small particles of borocarbides, chromium nitrides and titanium carbonitrides (black) are also present. The borocarbides are mainly located at the grain boundaries, forming a stereoplasmic substructure. The chromium nitrides and titanium carbonitrides are distributed homogeneously throughout the microstructure. As the size of carbides, nitrides, and carbonitrides particles are very small, they cannot be easily distinguished under an optical microscope.
Shows the microstructure of Kh12MFL upon quenching. The microstructure consists mainly of various shades of grey, although some white and black particles can be observed. The white particles are mainly apartite, while the black particles represent borides, chromium nitrides, and titanium carbonitrides. The borides are mainly located at the grain boundaries, forming a stereoplasmic substructure, while chromium nitrides and titanium carbonitrides are widely dispersed throughout the microstructure.
Both 150KhNML and Kh12MFL steels exhibit excellent wear-resistant properties due to the presence of a fine and homogenous distribution of particles of borocarbides, chromium nitrides and titanium carbonitrides. In addition, the very fine ferrite grains provide improved ductility and shock resistance, making these steels well suited for applications in which wear resistance, durability and strength are important.
In conclusion, the microstructure of wear-resistant steels 150KhNML and Kh12MFL upon quenching consists mainly of fine pearlite grains and small particles of borocarbides, chromium nitrides and titanium carbonitrides. The presence of these particles gives great wear-resistance to the steels, making them well suited for applications where enhanced wear-resistance, ductility and strength are required.
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