A technique, developed at the Massachusetts Institute of Technology (USA), that transforms the microscopic structure of metals can enable energy-efficient 3D printing of blades for gas turbines or jet engines.

 

A new heat treatment developed by MIT transforms the microscopic structure of 3D printed metals, making the materials stronger and more resilient in extreme thermal environments. The technique could make it possible to 3D print high-performance blades for power-generating gas turbines and jet engines, enabling new designs with better fuel consumption and energy efficiency. Today's gas turbine blades are made using conventional casting processes in which molten metal is poured into complex molds and directionally solidifies. These components are made from some of the most heat-resistant metal alloys on Earth, as they are designed to spin at high speeds in extremely hot gas, extracting work to generate electricity in power plants and thrust in jet engines.

 

A thin rod of 3D-printed superalloy is drawn out of a water bath, and through an induction coil, where it is heated to temperatures that transform its microstructure, making the material more resilient. The new MIT heat treatment could be used to reinforce 3D-printed gas turbine blades.

Credit: Dominic David Peachey

 

There is growing interest in manufacturing turbine blades through 3D printing, which, in addition to its environmental and economic benefits, could enable manufacturers to rapidly produce more complex and energy-efficient blade geometries. But efforts to 3D print turbine blades still have to overcome a major hurdle: creep.

 

In metallurgy, creep refers to the tendency of a metal to permanently deform under persistent mechanical stress and high temperatures. While researchers have explored turbine blade printing, they have found that the printing process produces fine grains on the order of tens to hundreds of microns in size, a microstructure that is especially vulnerable to creep. "In practice, this would mean a gas turbine would have a shorter life or lower fuel efficiency," says Zachary Cordero, Boeing Career Development Professor of Aeronautics and Astronautics at MIT. "These are costly and undesirable outcomes."

 

Cordero and his colleagues found a way to improve the structure of 3D-printed alloys by adding an additional heat treatment step, which transforms the fine grains of the printed material into much larger "columnar" grains, a stronger microstructure that should minimize the material. yield potential, since the “columns” are aligned with the axis of greatest stress. The researchers say the method, described, paves the way for industrial 3D printing of gas turbine blades.

 

More information at https://news.mit.edu