Olutayo demonstrates how gas turbines can be more efficient and climate-smart

Olutayo Adegoke’s thesis offers new and valuable insights for, among others, gas turbine manufacturers wanting to reduce the climate impact of their products.

Gas turbines are used, for example, to produce heat and electricity in cogeneration plants. The turbine blades in a gas turbine must be able to handle extremely high temperatures. To this end, the Alloy 247LC is an excellent material to use. Conventional casting is currently used to manufacture turbine blades, but gas turbine manufacturers see major advantages in using LBPF instead, provided that the method is reliable.

“Since turbine blades have complex geometries, LBPF manufacturing is far more suitable than casting. It’s considerably easier to manufacture complex designs using LBPF, and there are almost no limits on component design,” explains Olutayo, who defended his thesis at University West on 16 December.

Reduced fuel consumption and increased efficiency

“In service, this means that turbine blades manufactured using LBPF can handle even higher temperatures than turbine blades that have been cast. This enables a reduction in fuel consumption, which increases efficiency. In turn, this generates lower carbon dioxide emissions, which lessens climate impact.”

He lists four more advantages of LBPF:

•   significantly shorter lead times within production
•   maximum material utilisation
•   little need for post processing
•   suitable for repairing components

Before a new manufacturing method can be used, any risk of cracks or other defects in the material must be eliminated. An alloy can react in completely different ways to different manufacturing methods. Accordingly, Olutayo has studied how Alloy 247LC is affected during powder bed-based additive manufacturing in great detail, that is, he has examined how the material’s microstructure and properties are affected by the relationships between the various parameters controlling the production process.

He has, for example, manufactured around thirty cubes of Alloy 247LC where he has tested different combinations of the parameters laser power, speed and hatch distance.

“It’s a case of finding the optimal combination of parameters where the material is completely free from defects and where you get the very properties you’re seeking.”

Unexpected discovery

“One unexpected discovery during my research work was that a small amount of silicon was detected adjacent to cracks, so it appears to play a key role in the development of such cracks. Since silicon isn’t usually included in Alloy 247LC, this would indicate the importance of thoroughly checking the chemical composition of, say, the alloy powder. So, by eliminating any unwanted silicon, we can probably reduce the risk of cracks in the material.”

Olutayo’s research findings can be of immense value in guiding industries wanting to continue efforts to develop and implement the manufacturing method for Alloy 247LC.

Olutayo spent five years working as a development engineer at Siemens Industrial Turbomachinery. Then, in 2017, he decided to continue his education and become a researcher at University West. Now a new assignment awaits him at the company’s R&D department in Finspång.

“I’ll continue developing materials for additive manufacturing in other product areas. The company’s workshop for industrial additive manufacturing in Finspång was the first of its kind in Sweden, and they’re well ahead of the competition even internationally when it comes to the additive manufacturing of metal components.”   

Read Olutayo Adegoke’s thesis: Processability of Laser Powder Bed Fusion of Alloy 247LC. Influence of process parameters on microstructure and defects