Page 9 - Research and innovation In advanced materials with application to the railway sector

Other contributions that come from the development of new or improved materials are, for
example, repairs through additive manufacturing, which allow for greater immediacy of
actions, even opening the possibility of on-site repairs, without the need to disassemble
damaged components. Apart from maintenance issues, additive manufacturing allows
reducing manufacturing time of original and spare parts on demand, the manufacture of
elements through reverse engineering or complex geometry.

It is also important to point out the incorporation of materials with greater damage
tolerance, which allow a more efficient management of maintenance actions, by reducing,
for example, the speed of crack growth and increasing, in general, the operating margin.
Another field of innovation in materials with a high impact on maintenance tasks is that of
self-healing materials, capable of regenerating damage and cracks.

ALLOYS

Perhaps the most important area in terms of the development of special metal alloys is the
one related to steel for rails. It is necessary to continue innovating in the development of
new steels and manufacturing methods that improve the mechanical properties (tensile
strength, elastic limit, fatigue behaviour and hardness) and extend their lifetime. In order
to do this, the microstructure that gives the rail the best mechanical properties is pearlite
and, specifically, fine pearlite (which has a shorter interlaminar distance), which gives the
rail greater hardness and resistance to wear, through heat treatments of the entire rail or
the head of the rail, or developing microalloyed steels, by using small amounts of
microalloying elements (Nb, V, Mn and Cr). Microalloyed steel can be an excellent choice for
obtaining fine pearlite microstructure, compared to just head hardened rails, because the
manufacturing costs and the technical manufacturing complexity are much lower.

MULTIFUNCTIONALITY

Multifunctionality refers to a range of technologies that add new functionalities to the
intrinsic properties of materials, through the addition of components mainly on a
nanometric or micrometric scale. Some applications in the railway sector are, for example,
the development and application of heatable coatings for de-icing and localized heating,
which results in a reduction of maintenance work and negative impact in areas susceptible
to ice formation. Ensuring a correct operation of the structure and minimizing risks of
brittleness of steels at very low temperatures.

Also, the functionality of including different sensors in elastic elements for monitoring
traffic conditions and road conditions. As a good example, it is worth highlighting the
incorporation of piezoelectrics in base plates, which are able to identify different levels of
load and displacements. This would allow its use, for example, in transition areas to identify
the presence of loose sleepers, or its use in areas intended for the dynamic weighing of
trains. The latter, in addition to monitoring the load of the trains, could provide information
on the response of the track for subsequent modelling and prediction of degradation and
need for maintenance.

Applications based on functional printing, already presented in the rolling stock section,
allow the integration of sensors, conductive circuits, electronic components and tracks,
lighting, heaters, etc.

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Position paper: Research and innovation in advanced materials with application to the railway sector
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