Special features of electron-beam boronizing of steels

Electron-beam treatment is a promising method of surface treatment. It can be used in traditional technological operations, i.e., melting, welding, so ldering, facing, quenching, and annealing, and in new processes, i.e., poly merization, local change of magnetic properties, recrystallization of the s urface layer, zonal melting, etc. Chemical heat treatment of a metal surfac e with a daubing applied by means of a powerful electron beam is an interes ting technique. By varying the composition of the daubing we can change the properties of the metal surface (wear resistance, corrosion strength, high -temperature strength, etc.). Electron-beam heating has some advantages ove r laser treatment, namely, ( 1) a high coefficient of the absorption of ele ctron beam by the metal, which makes it possible to treat the surface effec tively without absorbing coatings, (2) simplicity of organization of rapid scanning of the treated surface by the electron beam, (3) high efficiency o f the electron gun (up to 70 - 80%), (4) the possibility of creating quite compact technological electron-beam units with a power of tens and hundreds of kilowatts, (5) treatment in vacuum. In this connection interest in work s in this field has grown. The present paper concerns results of a study of the structure and properties of boronized layers deposited on carbon steel s by the method of electron-beam treatment under vacuum and by the traditio nal method for comparison.