Effect of heat treatment on structure of austenitic steel 07Cr25Ni13 obtained by WAAM

Abstract

Currently, the use of additive technologies in industry is becoming more promising. The intensification of development of 3D technologies leads to the need for a more thorough study of the structure and properties of metals obtained by this method. In this paper, the effect of heat treatment on structure of the metal deposited by Wire Arc Additive Manufacturing (WAAM) is considered. The paper describes the effect of quenching at various temperatures and annealing on the structure of austenitic steel 07Cr25Ni13. As a result of the work, it was found that during metal deposition, crystallization occurs according to the FA type with the formation of a coarse dendritic structure with mainly skeletal and vermicular morphology, consisting of δ- and σ-phases. It is noted that quenching at 1070 ℃ practically does not change the metal structure. Despite the fact that quenching at elevated temperatures (1100 ℃) leads to partial dissolution and spheroidization of the dendrites released during surfacing, there are no cardinal structural changes. The most complete dissolution of the dendritic component occurs during quenching at 1150 ℃. The structure after this procedure is predominantly austenitic, remains of the dendritic component are represented by small spherical inclusions. The steel structure after annealing (1150 ℃) practically does not differ from the structure obtained after quenching at the same temperature. A significant increase in grain size, typical for austenitic steels, is not observed in this case. Based on the structure obtained after heat treatment, the most promising treatment options for future physico-mechanical properties are quenching and annealing at 1150 ℃.