Microstructure and mechanical characteristics of VT1-0 alloy after rapid surface heat treatment

We study the distinctive features of the formation of microstructure and mechanical properties of VT1-0 commercially pure titanium subjected to rapid surface heat treatment. In a layer of the metal suffering the alpha -> beta -> alpha transformation, we observe the formation of an alpha-structure with larger grain sizes and a somewhat lower microhardness, whereas in the transition zone, between the layers heated to temperatures above and below the temperature of the polymorphic transformation {ie368-01}, the microhardness increases. The increase in the volume fraction of the layer heated to a temperature above {ie368-02} is accompanied by a monotonic elevation of the strength properties and deterioration of the plastic characteristic of the metal. In the case of 100% heating above {ie368-03}, the fatigue limit of the metal becomes 1.5 times higher. On the basis of the accumulated results, we make a conclusion that the changes in the mechanical characteristics of the alloy are connected with the formation of thermal compression stresses caused by very rapid processes of heating and cooling of the metal (up to 400A degrees C/sec).