Selected Properties of P/M Ti-6Al-2Sn-4Zr-6Mo Alloy After Hot Deformation

Abstract

The Ti-6Al-2Sn-4Zr-6Mo (Ti-6-2-4-6) alloy is a novel α + β titanium alloy with low specific weight, high strength and corrosion resistance. It is mainly applied in the civil and military aircraft industry. Typical applications of the Ti-6-2-4-6 alloy include turbine engine compressors, compressor blades, and compressor discs. The common way to produce structural parts from the Ti-6-2-4-6 alloy is hot forging. At present, the stock for forging is usually obtained from cast material. An alternative for producing such preform can be powder metallurgy (P/M). The processing of compacts makes it possible to improve the quality of the microstructure and properties, and can be conducted using commercial processing lines for forming the cast stock. This research was aimed at the evaluation of the microstructure and selected properties of the P/M Ti-6-2-4-6 alloy after compression in various conditions. As the initial material, the mixture of elemental powders was used, which provides the possibility to easily obtain the desired chemical composition as well as reduce costs of production. The mixture of powders was hot-pressed. Chosen properties of the compacts were determined. The samples of compacts were subjected to compression tests. The influence of temperature and strain rate on the character of flow curves of the investigated P/M Ti-6-2-4-6 alloy was determined. The microstructure of materials after deformation was evaluated and compared. Numerical modelling of forging of the selected forging was performed using the finite element method QForm commercial software. The range of parameters was in accordance with the possibilities of the industry. Based on the results of numerical modelling, appropriate conditions of hot forging of a selected shape were determined. The designed parameters of the forging technology were verified by the trials performed in industrial conditions.