This project examined the use of a laser-based technology, laser cladding, to reduce defects in rail resulting from thermite field welds. Thermite field welds are often used by railroads to splice together continuous welded rail segments or to replace damaged sections of rail. These welds, however, often experience plastic deformation, or batter, along the heat affected zone (HAZ) of the weld. The objective of this project was to prevent excessive plastic deformation by means of laser cladding coatings. Laser cladding is a process to apply metal coatings using a laser as a heat source.
Previous attempts to use this procedure resulted in cracking of the cladding and poor toughness (resistance to fracture). This project examined the cracking problem, the toughness problem, investigated potential solutions, and explored the feasibility of using laser cladding in the field. Solutions to the cracking and toughness problems were developed; however, field testing revealed other problems, such as delamination of the cladding, that will have to be resolved for this procedure to be implemented
The contractor's report is available.
