ВИБІР ТЕХНОЛОГІЧНИХ ПАРАМЕТРІВ ЛАЗЕРА ДЛЯ ОТРИМАННЯ НАНОСТРУКТУР НА ІНСТРУМЕНТАЛЬНІЙ СТАЛІ У12А

Abstract

According to the improved model of the thermal interaction of laser radiation and the processing material, a study of the change in the maximum temperature at different depths of the surface layer was carried out on the example of tool steel U12A. The rate of change of the maximum temperature and temperature stress as a function of the heat flux density of laser radiation (LV) was also studied. The range of LV density was taken within q=108...1011 W/m2 for different times of its action, which corresponds to the conditions for the possible occurrence of NS. The study of the dependence of the rate of change of the maximum temperature on U12A steel on the density of the heat flow at different depths showed that during all times of its action, rates of temperature change of more than 107 K/s are realized, which indicates that, according to this criterion, the formation of NS is possible over the entire range of densities heat flow and at all investigated depths. To determine the possibility of accelerating the formation of NS, the values of temperature stresses in the zone of action on U12A were calculated at a density of 108...1011 W/m2 at different depths with an action time of t=10-4 ...10-10c. Which showed that the direct formation of NS from the action of temperature stresses is practically impossible, however, at a time of 10-5...10-4 of their values, they approach those required at a heat flux density of 1011 W/m2. In order to determine the technological parameters that ensure the production of NS, spatial dependences of the volume of NS on the heat flux density and the time of its action were constructed for the radius of the spot R=10-6 m (Fig. 8) and R=5•107 m (Fig. 9) . It was determined that obtaining NS is more realistic for the size of the spot 5•107 m, although the probability of obtaining them is also low. In fig. 10 and 11 show similar dependences for the grain size on the heat flux density and the time of its action for the spot size R=10-6 m and R=5•107 m when acting on U12A tool steel. The obtained spatial pictures allow, knowing the required grain size, to choose the technological parameters that allow them to be implemented. All this will be required during the development of the technology for obtaining strengthening nanostructured coatings on the cutting tool.