Neutron beam adds focus for better welds

Press-hardened boron steel is an ultra high-strength steel used across a variety of industries, including automotive, where it provides high strength and weight-saving potential, allowing for stronger yet lighter cars, with increased passenger safety.

In the automotive industry, a major joining method for boron steel components is resistance spot welding, with several thousand welds being made on a single car.

Spot welding exposes the boron steel sheet to very high temperatures, causing the metal to exceed melting temperature and then rapidly solidify on cooling. This results in a heat-affected zone, where the surrounding material contracts and its microstructures are altered.

WMG’s Dr Darren Hughes said: “Automotive manufacturers and designers want to understand the exact effects spot welding has on boron steel, as the heat-affected zones can exhibit reduced hardness, which can in turn reduce the components' strength.

“However, most conventional scanning methods will struggle to penetrate such a strong and challenging material so we decided to seek out a partnership with a research facility that could give us access to more powerful means of conducting non-destructive testing – a directed beam from neutrons beams generated by a nuclear reactor.”