Co-author Tobias Neuwirth adjusts the setup for the neutron grating...
Co-author Tobias Neuwirth adjusts the setup for the neutron grating interferometry at the ANTARES instrument of the research neutron source Heinz Maier-Leibnitz at the Technical University of Munich.
Source: B. Ludewig / TUM

Neutrons detect defects in 3D printed components

Researchers from the Technical University of Munich (TUM) have examined common methods used to locate defects inside components.

In the manufacture of turbines conventional processes often reach their limits. Therefore, additive manufacturing is increasingly used to produce complex, curved components with intricate structures.

A research team from the Technical University of Munich (TUM) has now examined common methods used to locate defects inside components. In their investigation neutron grating interferometry, performed at the Heinz Maier-Leibnitz research neutron source (FRM II), achieved the best defect detection.

Laser beam melting is a common 3D printing process for turbine blades with internal cooling channels. During this process, a laser melts a thin layer of metal powder in predefined areas. Layer by layer, the component forms in a bed of powder. Similar to an archeological excavation, the component is then exposed and the remaining powder can be reused for the next printing process.

However, process instabilities can lead to defects and reduce the strength of the component. Typical defects are pores and cracks. Even partial or total separation of individual layers can occur.

Defects in safety-relevant components, such as turbine blades, can lead to serious consequences. "We therefore need to examine critical components after the manufacturing process and of course do so non-destructively," explains Cara Kolb from the Institute for Machine Tools and Industrial Management at TUM.

For their experiments, the researchers produced test specimens with defects of different size and depth and then attempted their detection using non-destructive testing methods. This involved active infrared thermography (aIRT), ultrasonic testing (UT), X-ray computed tomography (CT) and neutron grating interferometry (nGI).

At the research neutron source doctoral student Tobias Neuwirth conducted the experiments at the ANTARES instrument. "We investigate components using neutron grating interferometry, observing the scattering and absorption of neutrons in a spatially resolved manner. Changes in these properties give us information about the type and size of the defects," he explains.

Each of the methods tested has both potential and challenges. Neutron grating interferometry is complex and more expensive than the other test methods investigated, but of all the methods, it detected the most and the smallest defects.

"Neutrons can penetrate deep into the material and resolve the internal component structure with high resolution. They are particularly suited to nickel-based alloys, which are enormously important for the additive manufacturing of structural components in aerospace," concludes Cara Kolb.

Research into testing procedures that non-destructively assure the quality of 3D-printed components is very important: Such procedures reveal the likelihood of a component failure during operation. They are also ever more important as additive manufacturing in aircraft and cars, for example, increases.

Subscribe to our newsletter

Related articles

Voxel-based technique to streamline bioprinting

Voxel-based technique to streamline bioprinting

Researchers have developed a new bioprinting technique based on voxels.

3D printing nanoresonators

3D printing nanoresonators

Researchers illustrated an innovative approach to developing miniaturized and multifunctional sensors.

3D printed copper components for linear accelerators

3D printed copper components for linear accelerators

For the first time, researchers have 3D printed essential quadrupole components for linear accelerators from pure copper.

4D printing: heat shrinks printed objects

4D printing: heat shrinks printed objects

4D printing could be used to produce parts that exhibit a specific behavior only after they take their predefined shape.

Diagnostic for Liquid Metal Jetting 3D printing

Diagnostic for Liquid Metal Jetting 3D printing

A diagnostic tool can determine the quality of metal droplets and monitor Liquid Metal Jetting (LMJ) prints in real-time.

Self-powered wearable devices

Self-powered wearable devices

Scientists have created a 3D printing method that integrates functional and structural materials to print wearable.

AI accelerates discovery of 3D printing materials

AI accelerates discovery of 3D printing materials

A new machine learning system costs less, generates less waste, and can be more innovative than manual discovery methods.

Nanoscale lattices flow from 3D printer

Nanoscale lattices flow from 3D printer

Rice University engineers create nanostructures of glass and crystal for electronics, photonics.

Aerogel: the micro structural material of the future

Aerogel: the micro structural material of the future

Scientists from Empa were able to 3D print stable well-shaped microstructures made from silica aerogels for use in biotechnology and precision engineering.

Popular articles

Subscribe to Newsletter