Researchers show heat treatment allows AM part to withstand extreme conditions

November 18, 2022

The new MIT heat treatment could be used to reinforce additively manufactured gas turbine blades, as shown above (Courtesy Dominic David Peachey)

Researchers from Massachusetts Institute of Technology, Cambridge, USA; University of Illinois; and Oak Ridge National Laboratory, Tennessee, USA, have developed a heat treatment that transforms the microscopic structure of additively manufactured metals to make the materials stronger and more resilient in extreme thermal environments.

In the paper ‘Directional recrystallization of an additively manufactured Ni-base superalloy,’ published in Additive Manufacturing, 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 behaviours of AM IN738LC were characterised through a parameter study in which the peak temperature and draw rate were each independently varied.

Recrystallisation began when the peak temperature was higher than the γ′ solvus of 1183 °C. Varying the draw rate from 1 to 100 mm/hr while maintaining a fixed peak temperature of 1235°C and a thermal gradient of order 105°C/m ahead of the hot zone showed that a draw rate of 2.5 mm/hr maximised the grain size, giving a mean longitudinal grain size of 650 µm. Specimens processed under these conditions also inherited the〈100〉fibre texture of the as-manufactured material. Close inspection of a quenched specimen revealed Zener pinning of the longitudinal grain boundaries by MC carbides and a discrete primary recrystallization front whose position followed the γ′ solvus isotherm.

The present 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 minimise 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.

“In the near future, we envision gas turbine manufacturers will print their blades and vanes at large-scale Additive Manufacturing plants, then post-process them using our heat treatment,” stated Zachary Cordero, the Boeing Career Development Professor in Aeronautics and Astronautics at MIT and lead author of the paper. “3D printing will enable new cooling architectures that can improve the thermal efficiency of a turbine, so that it produces the same amount of power while burning less fuel and ultimately emits less carbon dioxide.”

The full paper is published here.

In the latest issue of Metal AM magazine

Download PDF

Extensive AM industry news coverage, as well as the following exclusive deep-dive articles:

  • Revolution, not evolution: General Motors on building an AM culture and the AM Dream Machine
  • The power of Additive Manufacturing in the hands of artists: Public works to small batch production
  • Growing momentum and broadening recognition: A status update on the rise of Electron Beam PBF
  • Improving carbon capture efficiency through Additive Manufacturing in the race for a liveable climate
  • The System of AM Systems: How Metal Powder Works’ in-process powder production could change metal AM
  • The next generation: Using metal AM to drive emissions reduction and educate the engineers of the future
  • Advances in the AM of refractory metals and hard materials at the 20th Plansee Seminar
  • Additive Manufacturing needs you: Why you and your company should get involved in standards development

The world of metal AM to your inbox

Don't miss any new issue of Metal AM magazine, and get the latest industry news. Sign up to our twice weekly newsletter.

Sign up

News from the industry…

    News from the industry…

    Discover our magazine archive…

    The free to access Metal Additive Manufacturing magazine archive offers unparalleled insight into the world of metal Additive Manufacturing from a commercial and technological perspective through:

    • Reports on visits to leading metal AM part manufacturers and industry suppliers
    • Articles on technology and application trends
    • Information on materials developments
    • Reviews of key technical presentations from the international conference circuit
    • International industry news

    All past issues are available to download as free PDFs or view in your browser.

    Browse the archive

    Looking for AM machines, metal powders or part manufacturing services?

    Discover suppliers of these and more in our comprehensive advertisers’ index and buyer’s guide, available in the back of Metal AM magazine.

    • AM machines
    • Process monitoring & calibration
    • Heat treatment & sintering
    • HIP systems & services
    • Pre- & post-processing technology
    • Powders, powder production and analysis
    • Part manufacturers
    • Consulting, training & market data
    Download PDF
    Share via
    Copy link
    Powered by Social Snap