Laser powder bed fusion offers a possibility of production of Ni-based superalloys exhibiting fine microstructure with the desired texture containing almost no defects, all of which have a direct positive impact on the strength and fatigue properties [1,2]. On the contrary, creep properties deterioration might be expected due to the fine-grained structure. Therefore, adequate heat treatment can tailor microstructure via grain growth and precipitates’ size and spatial distribution. Heat treatment optimization is performed by a combination of theoretical and experimental methods. The theoretical approach is based on the phase-field models simulating grain growth starting from the initial microstructure obtained from SEM-EBSD observations. Therefore, initial grain morphology and crystallographic orientation will be taken into account in the model. The numerical models predict a set of suitable temperatures and times for the heat treatment. These parameters are tested in the heat treatment of the real samples and resulting microstructures are compared with the predicted ones. Differently heat-treated IN939 are tested by uniaxial tension to obtain their mechanical behaviour characteristics.

References

[1] R.C. Reed, The Superalloys: Fundamentals and Applications, 2008.

[2] B. Blakey-Milner et. al. Materials & Design, 2021, 209, 110008.