The key load-carrying components of modern high-speed railway vehicles are mostly large-scale welded metallic structures

in which inevitably exist various defects and damages during the manufacturing

operation and maintenance. It is usually argued that

after the safety assessment

those unacceptable quality defects and surface damage are called defects. These defects can considerably decrease the bearing capacity and service life of the structures

it is therefore necessary to repair the bearing parts in the case of defects. This paper summarizes the typical defects existing in the key load-carrying components of railway vehicles and corresponding repair technologies

and then we point out that the structural integrity assessment is the potential research topic and developing direction.