OBRABOTKA METALLOV

Abstract
The results of structure and properties investigations of the surface alloyed titanium substrate layers are discussed in present work. Built-up layers are produced by the electron-beam overlay welding of carbon-containing powder mixtures in the air. The powder mixtures of titanium, niobium and graphite as well as “niobium – graphite” and “titanium - graphite” compositions are used as the alloying materials. To protect materials from the influence of atmospheric gases during overlay welding, 50 % of the flux (CaF₂) was added to the powder mixture. The electron beam overlay welding allows to produce the high quality coatings with a thickness up to 1.7 mm. X-ray analysis of built-up layers revealed the presence of TiC, α-Ti and residual graphite phase. As a result of the treatment microhardness of surface layers increased from 1.8 to 4.8 GPa. The coatings produced by the method of electron beam overlay welding showed enhanced wear resistance in conditions of friction against non-rigidly fixed abrasive particles. Wherein the formation of coatings on titanium surfaces doesn’t cause the dramatically decrease of the material impact toughness.

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