Identification of dynamically precipitated phases in hot-working Inconel 718 alloy

Purpose: The main purpose of this paper was to analyze how localized flow/structural inhomogeneties that may develop during hot deformation can affect a precipitated phases and to determine what kind of particles are present in the microstructure of hot-worked Inconel 718 superalloy. Design/methodology/approach: Compression tests were carried out on precipitations hardenable nickel based superalloy of Inconel 718 at constant true strain rates of 10 -4 and 4x10 -4 s -1 at temperature of 720 and 850° C. The dynamic behaviour were explained through observation of the microstructure using standard optical, scanning and transmission electron microscopy. Precipitated phases were identified using EDS technique and based on selected area diffraction pattern. Findings: Microstructural observations of deformed at high temperatures, previously solution treated Inconel superalloy revealed non uniform deformation effects. Distribution of molybdenum- and niobium-rich carbides affected by localized flow was found. Microstructural examination of the alloy also shown shear banding penetrating through the whole grains. Practical implications: The experiments on hot deformation of age hardenable Inconel 718 superalloy and the analysis of dynamic precipitation process have a practical aspect. This interaction could become an important feature of high temperature performance and may also influence the production of specific structures of this material. Originality/value: Even though the number of research has focused on the hot deformation behaviour of Inconel 718, there is still scarcity of data referring to the analysis of dynamic structural processes which operate during hot deformation of this precipitation hardenable alloy: in particular dynamic precipitation and dynamic particles coarsening.