Mechanical Properties and Structure of Titanium-Alloy Overlays Alloyed With Oxygen from the Oxide Layer of Filler Rods
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MECHANICAL PROPERTIES AND STRUCTURE OF TITANIUM-ALLOY OVERLAYS ALLOYED WITH OXYGEN FROM THE OXIDE LAYER OF FILLER RODS V. K. Shatalov,1 A. P. Korzhavyi,1 and L. V. Lysenko1 Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 8, pp. 37 – 41, August, 2020.
Prospects of oxygen alloying of alloys in the process of deposition of rods on parts from titanium alloys aimed at raising their hardness are considered. Experiments on fabrication of samples of titanium alloys with remelting of filler rods with oxide coating formed by plasma electrolytic oxidation are performed. The main mechanical characteristics of the overlay rod material modified by introduction of oxygen from the oxide layer are determined and the structural features of the material are analyzed.
Key words: titanium alloys, rods, oxide layer, oxygen, hardness.
loped by CRISM “Prometey” on the basis of tungsten and molybdenum carbides or thermally oxidized rods with a Ti – Al – Zr composition. However, the choice of wires for depositing onto titanium alloys is complicated by the requirement that the material of the overlay should have a structure close to that of the substrate metal and be adaptable to manufacture. The mechanical properties of titanium and its alloys depend considerably on the contents of oxygen, nitrogen and carbon in them. The positive effect of these gases (especially of oxygen) on the mechanical properties of titanium alloys is known quite well. The strength and the ductility of titanium alloys can be controlled to a certain degree by varying the oxygen content. As an alloying element, oxygen reinforces the matrix, because its atoms distort the titanium lattice when introduced into the lattice voids [8, 9]. Since the alloying of titanium with oxygen is implemented directly during deposition of the rods onto the part, it is expedient to develop methods providing a controlled oxygen content in the deposited rods. Saturation of overlays from titanium alloys with oxygen is often implemented by deposition of stable oxide coatings onto the surface, for example, using a PT-7Msv filler wire [10]. Rods from PT-7Msv wire oxidized by a heat treatment are quite adaptable to the production process and yield quality overlays. However, the service life of the articles with them is relatively short. Moreover, despite the seeming simplicity, the method of thermal oxidizing has the following substantial drawbacks [10].
INTRODUCTION Engineering materials of our millennium are expected to possess special properties [1 – 4]. For example, the traditional materials for radar and marine equipment are produced today with the use of titanium [5]. Wide application of titanium materials in various industries is explainable by the unique combination of their properties such as the high specific strength, corrosion resistance in many aggressive environments, nonmagnetic nature, and high-temperature strength at up to 600°C. At the same time, titanium and its alloys are characterized by very low antifriction properties [
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