Effect of Heat Treatment on Microstructure and High Temperature Tensile Mechanical Properties of Selective-Laser-Melted GH3230 Superalloy

In order to effectively improve the comprehensive high temperature mechanical properties of GH3230 superalloy, the GH3230 sample was formed by selective laser melting technology, and the solid solution treatment was carried out according to the designed heat treatment system. The microstructure of the alloy before and after solution treatment was analyzed, the high temperature tensile mechanical properties of the alloy were tested, the influence of the morphology and distribution of precipitated carbides on the high temperature tensile mechanical properties was studied, and the mechanism of high temperature tensile fracture was discussed. The results show that the microstructure of GH3230 superalloy by selective laser melting is composed of single gamma solid solution columnar crystals with the same growth direction as the material stacking direction. After solution treatment, M6C type fine carbide particles with chain distribution are precipitated along the grain boundary of gamma solid solution columnar grains, and M6C type ultrafine carbide particles with dispersion distribution are precipitated inside the columnar grains. The columnar grains become coarser, and the grain orientation difference decreases, showing a trend of equiaxed grain transformation. The degree of anisotropy of high temperature tensile mechanical properties is weakened. Because the microstructure is still columnar grain with directional solidification characteristics, the mechanical properties of high temperature tensile in different directions are still different. Both longitudinal and transverse high temperature tensile fracture mechanisms are intergranular ductile fracture.