Transformations in the Surface Layers of Electroerosively Alloyed Carbon Steels During Tempering.

During tempering of carbon steel samples after electroerosive alloying transformations occur in the surface layers which, in essence, constitute decomposition of a supersaturated solution of tungsten in alpha -iron and the additional formation of hardening eta -carbides. These transformations occur both as a result of upward diffusion of carbon and as a result of redistribution of iron atoms at the higher temperature. These phase-transformation processes and also the specific features of electroerosive alloying which greatly increase the crystallographic defectiveness and block structure of the surface layer, lead to a noticeable increase in the diffusion mobility of carbon and to a reduction by almost an order of magnitude in the effective diffusion activation energy of this element.