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Research on Reliability Assessment on Repair and Remanufacturing of Worn Rails for Life Extension

Rail steel defects can lead to very expensive and time-consuming total rail replacement maintenance operations. Laser cladding repair of rail defects is a potential solution for on-site track repair applications. Reliability test trials at the Bishan Depot test track has demonstrated the concept. AFM has been approved for Main-line track tests. Development of an on-track portable laser cladding system is in progress. Laser cladding repair capability is needed to mitigate some total rail replacement maintenance for example localized defects and wear at the crossing nose and rail heads.
                
 
Reliability tests have been carried out on laser cladded rail specimens installed at the Bishan Depot test track since March 2017. The cladded material has shown good wear and durability performance. Wear monitoring with 3D surface scan and ultrasonic test show no deterioration of the clad material.Crossings and switches are of specific interest for potential laser cladding repair applications. The high costs and maintenance time for total replacement presents an opportunity to perform on-site laser cladding repair, restoring worn and chipped off nose sections of crossings and switch rail elements.
 
Cladding repair studies on the crossing nose are shown below. Hardness and microstructure studies were performed on the cladded specimen. Microscopic examination shows there are no void in the clad and interface of the clad and base material. A Singapore Provisional Patent has been filed for a portable laser cladding repair system to be developed for on-site rail steel repair applications targeted at high value on-site rail steel repairs for crossings and switches.