Powder catchment efficiency in laser cladding (directed energy deposition). An investigation into standard laser cladding and the ABA cladding technique

This paper investigates the efficiency of powder catchment in blown powder laser cladding (a directed energy deposition technique). A comparison is made between standard “track by overlapping track” cladding (“AAA” cladding) and “ABA” cladding, where the gaps left between an initial set of widely spaced tracks (“A” tracks), are filled in by subsequent “B” tracks. In both these techniques, the melt pool surface is the collection area for the cladding powder, and the shape of this pool can be affected by several parameters including cladding speed, intertrack spacing, and type of cladding technique. The results presented here are derived from of an analysis of high-speed videos taken during processing and cross sections of the resultant clad tracks. The results show that the first track in AAA cladding has a different melt pool shape to subsequent tracks, and that the asymmetry of the subsequent track melt pools results in a reduction in the powder catchment efficiency. In contrast to this, the geometry of the “B” track melt pools between their adjacent “A” tracks results in an enhanced powder catchment efficiency.