National University of Science and Technology “MISIS” (Moscow, Russia)

N. A. Chichenev, Dr. Eng., Prof., Dept. of Engineering Technology Equipment, e-mail: chich38@mail.ru
S. M. Gorbatyuk, Dr. Eng., Prof., Dept. of Engineering Technology Equipment, e-mail: sgor02@mail.ru
A. O. Karfidov, Head of Dept. of Engineering Technology Equipment, e-mail: a.korf@mail.ru
O. N. Chicheneva, Cand. Eng., Associate Prof., Dept. of Engineering Technology Equipment, e-mail: ch-grafika@mail.ru

One of the promising methods for improving the performance of technological tools is laser surface hardening, when metal is heated from the surface, while laser processing processes are characterized by a short exposure time and provide almost complete absence of deformations of the processed products. Tool steel Kh12M was chosen as the material for the study. Thermal hardening of samples, which were made in the form of a rectangular parallelepiped, was carried out on laser technological installations equipped with a continuous CO2 laser with a power of 1.5 kW. The depth of the laser exposure zone is chosen as the target function, which is an important operational characteristic of a technological tool that affects wear of its working surfaces. Based on the analysis of the results of a preliminary experiment with samples made of steel Kh12M, the values of the technological parameters of laser processing and the thermophysical characteristics of the processed material were determined. An experimental plan was developed, at each point of the matrix of which 3 experiments were carried out, while 72 experiments were conducted to find dependence of the depth of the laser exposure zone. Analysis of the experimental results shows that the maximum hardening depth of samples made of steel Kh12M without melting the surface was 0.75–0.80 mm; greater depth is achieved under conditions that cause melting of the surface. To obtain generalized statistical dependencies, the obtained data were transformed, taking into account the definite dimensionless (generalized) parameters. As a result of mathematical processing of experimental data, the formula was obtained for determining the relative depth of the hardened zone at the specified parameters of laser processing without melting the surface.

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