Metallurgical characterisation of a historical metal tie-rod from Milan Cathedral

A neutron diffraction and imaging study of ancient iron tie rods

“…Following a classic metallurgical approach, some preliminary results were obtained (Bellanova et al, 2015). The material is extremely heterogeneous both in terms of microstructures and defects.…”

“…Limit analysis was employed with the aim of understanding the structural behavior of the vaults and finding load paths inside the 2018 JINST 13 C05009 masonry (Vasic and Coronelli, 2014). In order to provide a deeper material characterization, both a metallographic investigation (Bellanova et al, 2015) and a toughness test (Gianneo et al, 2017) were carried out on the original material. Finally several studies were performed to define nondestructive techniques able to detect dominant flaws.…”

A feasibility analysis on the application of eddy current testing to the detection of the most detrimental defects in historical metallic tie-rods

“…A non-uniform scenario was discovered: the measured stresses vary from 0 to 150 MPa and several tie-rods showed dynamic anomalies. Furthermore, metallurgical and preliminary NDT investigations revealed a material significantly different with respect to a modern steel or iron: the microstructure is very heterogeneous and a high inherent defectiveness is exhibited at different observation scales [11].…”

“…2. Inclusions: regions of the simulated tie-rod characterized by different electro-magnetic properties, in particular those of silica inclusions observed in tie-rods [11]. The considered dimensions varied in terms of depth, width and length in the range of 0.1-3 mm, 0.1-3 mm and 0.1-10 mm, respectively.…”