Effect of Homogenization Temperature on Microstructures of IN718C Alloy with Different Solidification Cooling Rates

摘要

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