Heat Treatments Effects on Nickel-Based Superalloy Inconel 713C

The purpose of this work is to study the effect of heat treatments on the microstructure of the nickel-based superalloy Inconel 713C. Three different conditions were studied and the results compared: (1) as cast; (2) solid solution treatment (1179 degrees C/2 h) and (3) stabilization heat treatment (1179 degrees C/2 h plus 926 degrees C/16 h). Inconel 713C is normally used in the as-cast condition, an improvement in the 980 degrees C stress-rupture life is often obtained by a solution heat treatment. However, the material in this condition tested under high stress at 730 degrees C shows a marked decreased in rupture life and ductility. The mechanical resistance in creep increases in Inconel 713C by precipitation hardening phase, with gamma' (Ni3Al) formed during the heat treatments. The characterization techniques used were: chemical analysis, hardness testing, X-ray diffraction, optical microscopy and scanning electron microscopy (SEM), EDS analyzes and thermocalculation. The SEM and EDS analysis illustrated the gamma, gamma' and carbides. The matrix phase (gamma), has in its constitution the precipitation of the gamma' phase, in a cubic form, and in some regions, carbides were modified through the heat treatments. (M23C6-type) and boride (M3B2 type) identified with the use of the thermocalculation. The heat treatments increase the relative intensity of niobium in the carbides. The hardness test was not achieved because the material was overaged.