M. KUKURYK*,# ANALYSIS OF DEFORMATION AND MICROSTRUCTURAL EVOLUTION IN THE HOT FORGINGOF THE Ti-6Al-4V ALLOY ANALIZA ODKSZTAŁCENIA I PROGNOZOWANIA MIKROSTRUKTURY W PROCESIE KUCIA STOPU Ti-6Al-4V NA GORĄCO

A majority of high-strength constructional elements of titanium alloys are manufactured by hot plastic working methods, chiefly by open die forging or die forging. Most often, β α + two-phase titanium alloys are used, which are characterized by high relative strength, good hightemperature creep resistance (up to 450°C), high fatigue strength under corrosive conditions, corrosion resistance in many media and good weldability [1]. A determining influence on the mechanical and service properties of a product is exerted by temperature, the method, nature and magnitude of deformation and the heat treatment of the blank [2]. The great non-uniformity of deformations in the forging process makes the production of internal-quality titanium forgings much more difficult compared to imparting the proper shape and geometry to the forgings [3]. In order to maintain a relatively small gradient of properties within the entire volume of the blank and, at the same time, their required level, cogging forging is used in anvils with a purpose-designed shape [4]. In the hot plastic working of titanium alloys, many factors are involved, which make the obtaining of products with the required microstructure and properties difficult and sometimes even impossible; these include: high affinity of titanium to oxygen, their low thermal conductivity and high heat capacity, which lead to the localization of heat during stock deformation and significant dependence of plastic flow resistance on the strain rate [5]. During deformation, micro-regions occur in the blanks, which differ in the value of temperature due to the physical properties and the features of the allotropic change and the deformation conditions. The determination of temperature distribution within the deformation zone during the titanium alloy forging process is important because of A R C H I V E S O F M E T A L L U R G Y A N D M A T E R I A L S