Effect of oxidation on mechanical properties and surface condition of heat-resistance titanium alloy VT41

Abstract

The present article dedicated to influence of oxygen affected zone of VT41 heat-resistant titanium alloy's samples. The samples were made of 023 mm rods and 1 mm thick sheets and processed by short term heat treatment at 300 - 900°C in atmosphere furnace. Mechanical properties of samples were measured at room temperature by straining (rods) and bending (sheets) Surface of fractured samples were studied by means of ТЕМ. The results of the present work gave an opportunity to match the temper colors of the samples with the temperature of heat-treatment, mechanical properties and the depth of fragile oxygen affected zone. The dependencies of relative strain and reduction area versus heat-treatment temperatures were determined. It was defined that a critical changing of plasticity's characteristics appears at heattreatment temperature above 500°C. The appearance of bright temper colors leads to enlarging of dispersion of ultimate stress and critical bending angle. When temperature of annealing goes up to 800°C the bending angle of sheet-samples decrease significantly at room temperature. As accurate measuring of the depth of oxygen affected zone and thickness of Ti02 layer by means of optical metallography and fractography at low temperatures is seriously complicated than one could qualify a depth of oxygen affected zone on the spot by determining an annealing colors. The appearance of bright yellow annealing colors with metal shining didn't bring any critical changes of mechanical properties.