Microscopic mechanism analysis and crystal plasticity modeling of high-temperature creep behavior of selective laser melted IN718

Due to their lightweight and monolithic forming characteristics, selective laser melted (SLM) nickel-based superalloys exhibit broad potential applications in aerospace and automotive industries. However, their unique microstructure leads to distinctive creep behavior. It is crucial to clarify the microstructural characteristics and underlying creep mechanisms of these alloys. In this work, creep experiments of SLM IN718 were conducted under different temperatures and holding stresses. And the evolution of grain size, precipitate state, and dislocation density in IN718 was investigated by scanning electron microscope and electron backscatter diffraction. Both carbide precipitation and dislocation density were identified as the main factors weakening the creep life and ductility of SLM IN718. Experimental results indicated that higher initial dislocation density and finer grain size lead to a reduction in creep life. Moreover, the precipitation of carbides and M23C6 under elevated temperature and high holding stress promotes micro-crack propagation and weakens creep strength. To simulate the mechanical behavior observed in high-temperature creep experiments, a crystal plasticity model coupling dislocations and precipitated solutes was developed based on the microstructural characteristics and deformation mechanisms of SLM IN718. This model enhances the fundamental understanding of the micro-mechanisms underlying the creep behavior of SLM IN718 and provides valuable insights for optimizing the design of high-performance components under extreme conditions.