Research On Forming Process And Properties Of Hastelloy X Alloy Prepared By Selective Laser Melting

Because of its outstanding corrosion resistance and high temperature strength,the Hastelloy X alloy is widely employed in the aerospace industry.However,there is a lack of experimental data on the basic structure of SLM formed Hastelloy X alloys,relatively little research on thermal deformation behavior,and shallow investigation of the influence of multidimensional forming factors.These constraints have limited the development of SLM forming of Hastelloy X alloys.As a result,this thesis studies Hastelloy X alloy from several process viewpoints using SLM technology,characterizes Hastelloy X alloy microstructure evolution and mechanical property characteristics,and systematically elaborates Hastelloy X alloy hot deformation behavior.(1)A finite element model was established to numerically simulate the transient temperature field and cooling rate changes during the forming process.The transient peak temperature of temperature field of SLM Hastelloy X alloy decreases with the increase of scanning speed and increases with the increase of power.The average cooling rate decreases with the increase of scanning speed and increases with the increase of power.The average cooling rate reaches 3.97×106℃/s.The magnitude of the predicted molten layer size is consistent with the results of the experimental session.(2)Single-pass scanning formation of Hastelloy X alloy was done utilizing various scanning speeds and laser powers based on the process features of SLM technology.With rising laser power and decreasing scanning speed,the clad layer’s height and width steadily grow larger.The P=140-240W and V=600-1400mm/s process window for SLM forming of Hastelloy X alloy was determined by combining the forming single-pass morphology.(3)Different forming angles of Hastelloy X alloy specimens were prepared to evaluate the differences in mechanical properties of Hastelloy X alloy under different forming angles.Simultaneously,the anisotropic variations of Hastelloy X alloy under various forming angles,the composition of forming defects,and the mechanical reasons were investigated in conjunction with the microstructure and fracture morphology,with 30° being the favored forming angle.At this point,the mechanical qualities are outstanding,meeting the requirements of the HB 5497-1992 aerospace industry standard.(4)With increasing deformation temperature and decreasing strain rate,the peak rheological stress during thermal deformation falls.The constitutive equation were developed using the rheological stress curve and dynamic material model to investigate the effects of deformation temperature and strain rate on microstructure evolution and dynamic recrystallization.The microstructure is stable and dense at high temperatures and low strains,there are no visible microcrack faults,the DRX grains are more uniform,and the high temperature and low strain region is more appropriate for Hastelloy X alloy thermal processing.