Calling it “a significant milestone,” researchers at the Department of Energy’s Oak Ridge National Laboratory (ORNL) said they became the first to 3D-print large rotating steam turbine blades.

The demonstration, led by Siemens Technology, shows the viability of wire arc additive manufacturing for scalable production of components larger than 25 pounds, researchers said.

Traditionally, such parts were produced through casting and forging facilities, many of which have moved overseas.

“There’s now a realization that we cannot get low-volume castings and forgings that exceed 100 or 200 pounds from the domestic supply chain,” said Michael Kirka, lead research and group leader for the Deposition Science and Technology group at ORNL. “It’s put us in an untenable position, especially as we see how international conflicts have affected the international movement of critical supplies.”

Wire arc additive manufacturing employs an electric arc to melt metal wire in a process controlled by a robotic arm. This gradually builds thin layers of metal into the desired shape. The wire-arc technology used to manufacture the turbine blade was developed in collaboration with Lincoln Electric under a cooperative research and development agreement.

Because wire arc manufacturing is based on welding technology, researchers said it is easily used for repairing existing parts. This could allow companies like Siemens Energy to more easily maintain and upgrade equipment under service contracts with electric utilities. 

When the Siemens wire arc research began in 2019, it initially focused on component repair. However, the scope expanded during the COVID-19 pandemic, when the wait for new cast steam turbine blades stretched to two years.

From there, the project broadened to include printing entire replacement parts, because these types of turbine engines are versatile enough to use in gas, coal and nuclear power plants, Kirka said.

The project’s original goal was to print only 25% of the blade’s top section, but the capabilities of the wire arc setup led to printing the entire blade in one build. The scanning ability during the printing process provided essential information for machining, reducing production time.

While the traditional wait for large castings and forgings has decreased to seven or eight months, ORNL said it completed the printing of the blade in just 12 hours, with the entire process, including machining, taking two weeks.

Siemens is collaborating with the Electric Power Research Institute (EPRI) for nondestructive evaluation and testing. Despite the decreased wait times for traditional manufacturing methods, researchers said the 3D-printed blades offer advantages in terms of on-demand manufacturing and replication of any design.

They added the success of this case study opens possibilities for large-scale components in the future.

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