New Heat Treatment for Metal AM Parts in Extreme Conditions

New MIT heat treatment for extreme conditions. (Courtesy Dominic David Peachey)

Researchers from Massachusetts Institute of Technology, University of Illinois, and Oak Ridge National Laboratory have developed a metal additive manufactured heat treatment to make the materials stronger and more resilient in extreme thermal environments.

“Directional Recrystallization of an Additively Manufactured Ni-base Superalloy,” published in Additive Manufacturing, described how researchers converted the fine as-built grain structure of Ni-base superalloy AM IN738LC to a course columnar one via directional recrystallisation. The directional recrystallisation behaviors of AM IN738LC were characterized through a parameter study in which the peak temperature and draw rate were each independently varied.

The results demonstrate – reportedly for the first time – how directional recrystallisation of additively manufactured Ni-base superalloys can achieve large columnar grains, manipulate crystallographic texture to minimize thermal stresses expected in service, and functionally grade the grain structure to selectively enhance fatigue or creep performance.

This technique may make it possible to additively manufacture high-performance blades and vanes for gas turbines and jet engines, enabling new designs with improved fuel consumption and energy efficiency.