Development of an all-position YAG laser butt welding process with addition of filler wire

Abstract Construction of electric power generating stations and chemical plants routinely involves the provision of large numbers of fixed welded pipelines. Conventional arc welding, while only achieving a slow welding speed, specifically requires welds to be laboriously built up in multiple layers inside large grooves during welding of thick plates in what is essentially a highly elaborate and time-consuming process.1, 2 On the other hand, laser welding, in the wake of high-power enhancement of welding facilities seen in recent years, while allowing high-speed welding of thick plates, requires welds to be fitted up with a high degree of accuracy and small gap tolerance in order to produce good-quality joints. Electron beam welding has further been developed as an alternative process for welding of fixed pipelines,3 although this process faces some important problems, such as availability of bulky equipment for evacuation of welds and restricted applications to large-diameter pipes to ensure sufficient ac...