Laser Cladding of Welds to Improve Railroad Track Safety
This project explores the use of a laser-based technology, laser cladding, to reduce surface and near-surface defects resulting from thermite field welds of rail. Thermite field welds are used to splice together continuous welded rail segments or to replace damaged sections of rail. Thermite welds, however, often experience plastic deformation, or batter, along the heat affected zone (HAZ) of the weld. The objective of this project was to develop a procedure to prevent excessive plastic deformation along the HAZ by means of laser cladding coatings. Initial project tasks included the evaluation of powders and the selection of a powder composition for use in the cladding process, and an investigation of alternative heat treatment protocols to solve a common cracking problem associated with laser cladding. Sample sections of laser-cladded rail welds were then prepared using the revised process. These test sections were installed and tested in the tracks at a testing facility. The objective of these tests was to subject the test welds to 50 MGT (million gross tons) of heavy axle load train traffic and to monitor the performance of the cladded welds during the tests. A preliminary assessment of the process necessary to apply laser cladding in the field was also conducted. This included in situ heat treatment using induction heating and a preliminary assessment of other elements of the process including the use of computer numerical control or robot arms. Based on a limited sample of six welds made using the laser cladding procedure developed in this project the new heat treatment protocol appears to have solved the cracking problem. The appearance of pores on two of test welds indicates the need for further investigation to determine the cause and cure for this problem. The delamination of the cladding on two welds installed in the test track also indicates the need for additional investigation. Further consideration of laser cladding would also require a more comprehensive investigation of the entire process of laser cladding of thermite welds in the field from the standpoints of practicality and costs.
- Record URL:
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Supplemental Notes:
- This IDEA project was conducted by University of Houston, Texas.
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Authors:
- Robles Hernandez, Francisco C
- Okonkwo, Anderson O
- Publication Date: 2015-6
Language
- English
Media Info
- Media Type: Digital/other
- Edition: Final Report
- Features: Figures; Photos; References; Tables;
- Pagination: 29p
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Serial:
- Safety IDEA Program Project Final Report
- Issue Number: 22
- Publisher: Transportation Research Board
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Publication flags:
Open Access (libre)
Subject/Index Terms
- TRT Terms: Cladding; Coatings; Cracking; Field tests; Lasers; Plastic deformation; Powders; Railroad tracks; Thermit welding; Welded rail; Welds
- Subject Areas: Materials; Railroads; I34: Steels and Metals;
Filing Info
- Accession Number: 01575592
- Record Type: Publication
- Report/Paper Numbers: Rail Safety IDEA Project 22
- Files: TRIS, TRB, ATRI
- Created Date: Sep 9 2015 10:57AM