Discoloration on Laser Welds of AISI 321 Tubes

In this contribution, a fabrication problem is discussed, related to Laser Beam Welding (LBW). Strictly speaking, the case study presented herein does not constitute a failure as such, since the subject components never made it to component service. In the narrow sense of the word, a component failure happens if and when a part does no longer serve its proper function. This is definitely not the case in the study put forward in this paper. However, one could argue that a product that cannot be marketed for lack of certain properties, or because of certain shortcomings, is rendered worthless for the manufacturer and this, in turn, could be considered a failure. In this case study, the issue of discoloration on the surfaces of welded austenitic stainless steel is discussed. This is a well-known and well-researched fabrication problem. Dependent upon service conditions of affected parts, discoloration might be detrimental to the normally outstanding corrosion resistance of this class of high-alloy steels.