Abstract
Structural and phase changes occurring in laser-hardened steels after tempering at different temperatures are considered. It is shown that the optimization of laser processing and subsequent tempering allows to increase the heat resistance of steels 50-120°C by maintaining a high density of defects in the crystal structure and appearance of the uniform allocation of dispersed carbide particles. It is established that for the laser-irradiated metal, from the energy point of view, it is not the formation of ε-carbide during tempering, but the deposition of carbon atoms and alloying elements on structural imperfections with further formation of carbides according to the scheme: carbon in solid solution → carbon associated with defects → carbide on defects of the crystal structure.
Highlights
One of the main characteristics of steels, especially tool steels, is heat resistance, which has a decisive influence on the change in strength properties during operation, and on such indicators as crumple resistance, wear resistance, heat resistance, etc. [1-10]
Pulsed laser treatment of steels can increase the hardness of the irradiated areas to 811,5 GPa, heat resistance by 50-120OС, which contributes to improving the performance properties of hardened products
The main reasons for the increase in operational properties are the features of the structural state of the irradiated metal: fragmented structure of the main phases; incompleteness of homogenization processes with partial or complete dissolution of excess phases; increased density of defects in the crystal structure
Summary
One of the main characteristics of steels, especially tool steels, is heat resistance, which has a decisive influence on the change in strength properties during operation, and on such indicators as crumple resistance, wear resistance, heat resistance, etc. [1-10]. Determination of the resistance of structures obtained as a result of processing with highly concentrated energy flows to softening when heated to different tempering temperatures makes it possible to reliably differentiate the methods of surface hardening of steels by the temperature areas of operation of products of various functional purposes. The achievement of high concentration inhomogeneity and saturation of solid solutions with carbon atoms and alloying elements, high density of defects in the crystal structure during laser processing create prerequisites for increasing the heat resistance of the hardened metal. Heating during tempering of the irradiated steel leads to the formation of a large number of dispersed matrix allocations, which increase the mechanical characteristics of the metal
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