PSI - Issue 53

Daniel R. Galán-Rivera et al. / Procedia Structural Integrity 53 (2024) 407–415 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 1. Rail geometry with machined area detail.

Five different metal powders were selected to perfume the repair on the base material: • Mn-Cr powder called in this paper “ Material 1 ” (%Mn & %Cr > 14%) • Cr-Ni-Mn powder called in this paper “Material 2” (%Cr, %Ni & % Mn > 6%) • Martensitic stainless steel called in this paper “Material 3” (%Cr > 13%) • Co-base material with high C called in this paper “Material 4” (%Co > 60% & %C > 0,9%) • Co- base material with low C called in this paper “Material 5” (%Co > 60% & %C < 0,3%)

2.2. Repair welding procedure Recovery techniques using laser repairing were performed under laboratory conditions. Laser equipment was LDL 160-3300 direct diode laser with a 3,3kW maximum power. The laser was mounted on a 6 axes IRB42400 robot system from ABB. The circular shape of the delivered beam was focused to a spot size of 3,75 mm on the work piece. The powders were paced in a power feeder by Medicoat. The powder was transported by an argon (Ar) stream to a powder lateral nozzle of 1,6 mm diameter and blown on the substrate at the same laser beam incidence point. This system is based on the volumetric powder flow control. Powder is continuously fed on a rotating turntable. The dimension of a feeding grove in the top plate, which is in contact with the turntable, and the rotation speed together, define the volumetric quantity of powder. The carrier gas moves the powder from the powder feed systems to the nozzle. The first step has been to obtain the adequate parameters to achieve a free defect overlay for each of the metal powders subjected to study. Parameters such as power, laser beam displacement speed, powder flow, gas flow and distance from the nozzle to the specimen, have been varied in order to obtain de optimal setting parameters in theses previous tests. In all cases, specimens were placed in a Demmler table, fixing it in 45 degrees from vertical. This geometry facilitates repairing of tramway rail because surface for working is completely horizontal (Fig. 2).

Fig. 2. Setting up specimens over Demmeler table.