Moscow Automobile and Road Construction State Technical University, Moscow, Russia:

I. S. Belashova, Dr. Eng., Prof., Dept. of Technology of Structural Materials

Vyatka State University, Kirov, Russia:
E. A. Marinin, Cand. Eng., Associate Prof., Dept. of Information Technologies in Mechanical Engineering, e-mail: e.marrini@gmail.com
V. A. Lisovsky, Cand. Eng., Associate Prof., Dept. of Materials Science and Design Basics

The paper presents the results of resistance and hardness tests for steels hardened by alloying with the use of laser emission. Alloying is performed directly into the liquid phase considering the convective mixing. The mechanism of mass transfer for laser alloying with convective mixing is shown and explained in the paper. It was established that different etchability and jumping changes in microhardness are connected with a change of the concentration of alloying elements in the volume of the melting bath. These jumps in microhardness are characteristic of the mixing mechanism during the laser alloying and do not depend on the type of alloying element. A method for calculating the tool wear of low alloy and carbon steels subjected to laser alloying to produce wear-resistant layers of very hard. The method is based on the introduction of a new parameter – the integral of the microhardness, which is simply calculated from the results of the experiments. The relative wear is equal to the ratio of the wear of the modified surface layer to the wear of the tool in the absence of hardening under the same operating conditions. The relative wear is a dimensionless value characterizing the reduction of wear (increase of resistance) of the modified surface layer. The integral microhardness of the modified surface layer is a dimensionless value characterizing the change of the microhardness of the entire modified layer to the microhardness of a homogeneous base metal layer of the same thickness. We construct the functional dependence of tool wear on this parameter. The offered approach to evaluate the effectiveness of surface hardening can be used not only in the special case of laser modification, but also for any other technology to create gradient-functional coatings.

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