Influence of the solution heat treatment on the behavior of γ′ precipitates and microhardness of dendrite core and inter-dendritic regions of cast superalloy GTD-111

In this research, the process of dissolution of γ' precipitates in GTD-111 casting superalloy was investigated. For this purpose, the dissolution operation was carried out at a temperature of 1100°C to 1230°C in 4 different times on samples prepared from the ingot with the aim of determining the effect of temperature and time on the behavior of the dissolution of the γ′ precipitates in the dendrite core and inter-dendritic regions. The microstructure of the samples was studied using the SEM and FESEM electron microscopes. Quantitative studies of microscopic images showed that complete dissolution of the initial γ′ precipitates occurred at 1230°C/40min for dendrite core regions and 1180°C/120min in the inter-dendritic regions. Investigating the micro-hardness of samples in the dendrite core and inter-dendritic regions of the specimens showed that the microhardness in these regions does not change with increasing temperature. Also the highest and lowest hardness was obtained at 1200℃ and 1120℃ in both regions respectively.