Effect of homogenization temperature on microstructures of IN718C alloy with different solidification cooling rates

Abstract

In order to reduce (he porosity and improve die performance stability of IN718C alloy castings, hoi isostadc pressing (HIP) process are usually conducted. Due to die different solidification conditions, die segregation and microstructure present various features in different posidons of castings, especially for castings showing large difference in wait diickness. The above mentioned factors can influence die effect of HIP, cause incipient melting of low melting point phase, such as Laves phase, then induce die scrapping ofcastings eventually. So it is necessary to conduct homogenization treatment for die castings widi large differences in solidification conditions before HP process. In this article, the as-cast microstructures of IN7I8C alloy widi different solidification cooling rates were studied, including segregation, phase constitution, etc. Then die microstructures of samples after homogenization treatment from 1075-1125 °C were analyzed. The effect of homogenization temperature on die elimination of segregation and dissolution behaviour of different phases were also investigated. Some relationships about homogenization temperatures, microstmctures and solidifica Uon cooling rates for IN718C alloy have been determined. They can be used to choose homogenization temperature for IN7I8C investment castings widi complex shapes before HTP process.