In situ Modulation of Residual Stresses During Laser Powder Bed Fusion

It has been well established that significant levels of residual stress can accumulate during laser powder bed fusion printing of metals. In extreme cases, these stresses can even lead to buckling or cracking during printing, ultimately causing build failures and scrap. The present talk will address in situ residual stress relief heat treatment strategies for Ti-6Al-4V that may be effective for cases where residual stress challenges cannot be mitigated using conventional, post-build stress relief heat treatments. Process modeling methodologies are combined with hole-drilling measurements to identify easy to compute metrics that correlate with residual stresses. These are then exploited to design more efficient processing strategies, followed by additional characterization (including detailed microstructure evaluation) to validate the approach. Finally, X-ray Diffraction measurements executed at the Cornell High Energy Synchrotron Source are employed to generate detailed spatial maps of residual stress, and critically to establish the effectiveness of location-specific residual stress relief heat treatments. Future opportunities for further refinement will be discussed.