A research paper authored by two NETL experts that explains how a new computational algorithm was applied to alloy development to optimize heat treatments and increase consistency of mechanical properties in nickel superalloys and steel castings was selected as one of only five editor’s choice open access articles for 2017 by the Journal of Materials Engineering and Performance(JMEP).

JEMP is a monthly peer-reviewed scientific journal published on behalf of ASM International that covers all aspects of materials engineering. The scope of the publication includes all substances used in engineering applications. Selection by the editors as a highlighted article reflects the comprehensive nature of the paper and its overall excellence.

The NETL paper, “Homogenizing Advanced Alloys: Thermodynamic and Kinetic Simulations Followed by Experimental Result,” was written by Albany, Ore.-based Paul Jablonski, Ph.D., and Jeffrey Hawk, Ph.D.
A process called segregation of solute elements (the enrichment of atoms, ions, or molecules at a microscopic region in a materials system) occurs in nearly all metal alloys during solidification. As a result, material properties can be severely degraded leading to later problems during processing. Heat treatments, known as homogenization, are often used to minimize segregation and improve performance. However, traditionally, those heat treatments can be time-consuming because they are based on trial and error experiments.

In the paper, Jablonski and Hawk documented and explained how they used modelling software to design a way to optimize the heat treatments. As a result, engineers can homogenize casting chemistries to levels that are appropriate for specific applications. The method also enables heat treatment schedules to be adjusted to fit limitations of heat-treating equipment, enabling routines to be used during commercial homogenization of ingots and castings. The process thus helps save time and money in manufacturing components for industrial uses.

NETL was involved in the research because better performing alloys for use in existing and advanced fossil fuel-burning energy systems are needed to increase efficiencies and reduce emissions. NETL demonstrated that thick-walled castings of nickel superalloys can behave similarly to wrought nickel superalloy counterparts – a critical step in proving the viability of large-scale manufacturing of advanced-ultra supercritical steam turbines.  

The process described in the paper helps improve creep and tensile strength in slow-cooled, thick-wall nickel superalloys and steel castings. In materials science, creep is the tendency of a solid material to deform under the influence of mechanical stresses. Tensile strength is a measurement of the force required to pull the alloys to the point where they break.

The U.S. Department of Energy’s NETL develops and commercializes advanced technologies that provide reliable and affordable solutions to America's energy challenges. NETL’s work supports DOE’s mission to advance the national, economic, and energy security of the United States.

Contact:

• Shelley Martin, DOE National Energy Technology Laboratory, 304-285-0228, contact.publicaffairs@netl.doe.gov