Neutron beam used to produce safer cars17/07/17Science & Technology
A project is using a stream of neutrons from the Institut Laue-Langevin’s (ILL) nuclear reactor to examine the safety critical welds in cars made with boron steel.
The project is led by the Warwick Manufacturing Group (WMG) at the University of Warwick, UK, with ILL, Tata Steel, and the Engineering and Physical Science Research Council (EPSRC).
Press-hardened boron steel is a high-strength steel used across a variety of industries. A large proportion of car manufacturers use boron steel for structural components and anti-intrusion systems in automobiles.
In the automotive industry, a major joining method for boron steel components is resistance spot welding, which exposes the boron steel sheet directly underneath the electrodes to high temperatures, causing the metal to exceed melting temperature and then solidify upon cooling.
WMG researcher 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.”
The partnership has begun to use neutrons generated from ILL’s reactor in its SALSA (Strain Analyser for Large-Scale Applications) beamline to examine the welds in boron steel, and to obtain data due to the neutron beam’s ability to penetrate heavy materials such as boron steel, and the fine resolution it provides.
SALSA team leader Dr Thilo Pirling said: “The SALSA beamline is a well-suited instrument for this study, as it specialises in determining residual stresses in a broad range of engineering materials, including steels. It also allows larger structures to be placed within the beamline.
“In this case, the non-destructive nature of the technique allowed the correlation of interest to be analysed effectively, as hardness profiles could be determined on the same weld following the neutron diffraction tests for residual stress.”