Effect of heating rate on the recrystallization process of GH4169 superalloy prepared by laser solid forming

The effect of heating rate on recrystallization process of laser solid forming (LSF) GH4169 superalloy is investigated by changing the heating rate of the sample during heat treatment. The effect of heating rate on recrystallization nucleation site, recrystallization grain growth rate and recrystallization grain distribution are analyzed experimentally. The results show that the lower residual stress of the inner part of each laser scanning path as the low heating rate can hinder the recrystallization process, so in order to make the sample recrystallization the heating rate must be higher than a critical value. With the increasing of heating rate, the recrystallization nucleation site changes from the only overlapping regions of two adjacent laser scanning paths to both the overlapping regions and the inner regions of laser scanning path, and this is beneficial to the uniform distribution of recrystallization grains. Furthermore, recrystallization grain growth rate increases with heating rate increasing within the parameters used in this experiment.