ADVANCED MATERIALS & PROCESSES | MAY/JUNE 2023 20 These services also included the distribution of the most important newspapers of that time, making information more accessible. Beginning in 1860, the railroads experienced rapid growth, connecting several capitals in the provinces and other production points with Buenos Aires. The system was not without obvious disadvantages, one being that the ends of its most important lines did not join, and several important cities were not connected. By 1910, the rail system in Argentina consisted of four main lines, all of which started at the port of Buenos Aires. These four lines were the Ferrocarril Oeste, Ferrocarril del Sur, F.C. Argentine Central, and the Buenos Aires Railroad to the Pacific. Due to the large investment of British capital in the construction and expansion of the railroads in Argentina, these were representative of the close ties between the two nations[3]. HISTORIC RAILWAY COMPONENTS This research work consists of studying two typical railway elements: a threaded bolt and a fixing nail; both are a constitutive part of any railway track. The railroad tracks examined in this case study were built by the Argentine Great Western Railway, a company that was later acquired by the Buenos Aires and Pacific Railways and today these pieces (threaded bolt and fixing nail) belong to the San Rafael Railway Museum, Mendoza-Argentina. “Fixing” is defined broadly as the main small material used to attach or fix rails to the sleepers (Fig. 2). The main functions of these rail fasteners were to: • ensure the consistency or invariability of the rail • facilitate the transfer of the static and dynamic loads to the infrastructure of the track (platform) exerted by the rolling stock on the structure of the track (railway package) • possess mechanical strength and constant elasticity throughout the long life of the fixation • contribute to good electrical insulation between both rails The number of required fixing pieces should be small to facilitate their manufacture, placement, and conservation, and minimize cost. The fixings for wooden sleepers can be divided into rigid and elastic defined by the way of carrying out the support and by the type of support: direct (without saddles) and indirect (with saddles). Rigid fixings (without saddles) include the nail hook and the screw. Elastic fixings (without saddles) include the single and double elastic nail, the shun, and gauge-lock (Pandrol clip) as shown in Fig. 3. The bolts are cylindrical body screws with a threaded end and varied heads, which serve to secure the plates to the rails. The head of the bolts tend to have a square or quadrangular design, and others have a diamond-shaped upper face. IRAM-FA Standard L 70-06 - June 84 - BULONS FOR ROAD, defines the technical requirements for track bolt material, manufacturing tolerances, and requirements for approval. Bolts are used for joints and other uses such as component of track apparatus. The fixing parts for the rails are manufactured following a variety of standards that consider dimensions, materials, and tolerances. They are usually machined from a single solid piece into the required shape and treated superficially to give them better properties. Specific features will depend on the manufacturer. Chemical compositions of typical modern fixing mails are listed in Table 1. The chemical composition of modern parts of a railroad are described below: • Carbon (C) (0.37 to 0.73%) It increases hardness and wear resistance, but also influences fragility. • Manganese (Mn) (0.86 to 1.74%) It has an influence on hardness, wear resistance, and toughness (not fragile), but decreases weldability. • Silicon (Si) (0.30%) Increases hardness, wear resistance, and facilitates rail rolling. • Sulfur (S) and phosphorus (P) (less than 0.05%) They are not desirable because they give fragility, but their elimination is very expensive. EXPERIMENT AND ANALYSIS This historical and metallographic research on railroad parts includes scientific analysis techniques such as metallographic analysis, hardness analysis, chemical composition study, and manufacturing process of the parts. By studying the pieces under a microscope with the acquired technical knowledge it is possible to interpret and “read” the message that the piece transmits. Using historical, geographical, and chronic bibliographies we’re able to cross examine that information and approximate a little more, which is useful for museums, schools, students, and teachers. Fig. 2 — Example of a hook-type fixing nail. TABLE 1 — CHEMICAL COMPOSITION OF MODERN FIXING NAILS %C %Mn %Si %P %S 0.37 – 0.75 0.86 – 1.74 0.30 Max Less than 0.05 Less than 0.05 Fig. 3 — Example of a gauge-lock (Pandrol clip).
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