Effect of solution parameters on microstructures and mechanical properties of K439B nickel-based superalloy

: The effect of different solution temperatures (1140 , 1160 degrees C and 1180 degrees C ) and cooling conditions (AC , FC-900 degrees C +AC ,FC ) on the microstructures and mechanical properties of K439B alloy were investigated using metallographic microscopy and field emission scanning electron microscopy (FE-SEM ). The results show that the optical microstructures and morphology of gamma' precipitates are similar and the width of grain boundary slightly increases after increasing the solution temperature. When cooled with AC , gamma' precipitates are uniformly distributed and the average size is 50. 7 nm ; when cooled with FC-900 degrees C+AC , the larger gamma' precipitates of 250-510 nm are precipitated at the interdendritic area region and near the grain boundary , exhibiting a bimodal gamma' microstructure ; when cooled with FC , the volume fraction of larger gamma' precipitates increases and the content of granular M 23 C 6 carbides at grain boundary improves. The stress rupture life of K439B alloy at 815 degrees C/379 MPa is enhanced after reducing the cooling rate , while different solution parameters have little effect on the room -temperature tensile property.