Investigation on the microstructure and tensile behavior of a Ni-based IN792 superalloy

The Ni-based IN792 superalloy is widely used in aeroengine components because of its low manufacturing cost and good mid-temperature (600°C–900°C) properties. However, its mechanical properties exhibit fluctuation with temperature, so a comprehensive understanding on the tensile behavior of IN792 superalloy at different temperatures is necessary. In this article, IN792 superalloy was fabricated and heat treated with the standard heat treatment of 1120°C/2 h air cooling + 1080°C/4 h air cooling + 845°C/24 h air cooling, and its tensile behavior at 550°C, 600°C, 650°C, 700°C, 760°C, 850°C, and 900°C was investigated. The results showed that IN792 superalloy exhibited obvious anomalous yield and intermediate temperature brittleness behaviors. The yield strength and ultimate strength of IN792 superalloy changed little below 760°C, but decreased significantly as the temperature increases to above 760°C. The ductility of IN792 superalloy had a little increase between 550°C and 600°C and then decreased significantly at 650°C and 700°C. As the tensile temperature increases from 700°C to 850°C, the ductility of IN792 superalloy increased again. However, when the temperature continues to rise to 900°C, the ductility dropped greatly. Such a tensile behavior of IN792 superalloy should be ascribed to the microstructure, such as the MC carbide, γ/γ′ eutectic structure, and γ′ phase.