CHARACTERISTIC FEATURES OF THE SURFACE RELIEF FORMATION OF METALS MODIFIED BY COMPRESSION PLASMA FLOWS

Abstract

Action of compression plasma flows (CPF) is a promising high-energy method for material modification ensuring uniform distribution of components in ultradeep (to about 100 μm) modified layers. In the present paper, using the scanning electron microscopy, we studied the surface relief and the thickness of a modified layer of W108 steel treated with compression plasma flows. To generate a plasma flux under experimental conditions, a magnetoplasma compressor of compact geometry with an energy storage battery of 15 kJ was used. It was established that during CPF action, the molten layer of material under the action of high-density plasma spreads over the surface. After the end of exposure, at the stage of rapid crystallization of the melt, a developed surface relief is formed with a height difference from 1 to 80 μm. With increase in the energy parameters of the acting CPF, the surface irregularities first increase and then decrease again, which is associated with the melt entrainment in the liquid phase. The dependence of the average melting depth of steel on the power density of the CPF action has been established. It is shown that the heat transfer model based on the Stefan problem allows one to predict the average melting depth of the target with sufficient accuracy; however, to determine the actual thickness of the modified layer, hydrodynamic entrainment and surface irregularities should be taken into account.