Casting defect terminology: cold shut vs. cold shot – casting defects in investment cast turbine blades made of nickel-base superalloys

Abstract High service stresses in investment cast rotating turbine blades of large gas turbine engines require high-quality castings, free of defects that could propagate into cracks and fractures during engine service. If such defects are detected in fabrication, affected castings will usually have to be scrapped, lowering the yield rate and driving production costs. To eliminate such defects from further production parts, it is imperative to understand the nature of these casting flaws, and to learn the mechanisms and process problems that caused them in the first place. In this context, it is important to follow a precise terminology and to differentiate between individual casting defects by designating them correctly. In this contribution, two casting defects in investment cast turbine blades, made of two different nickel-base superalloys, are described that have basically the same formation mechanism, but exhibit different defect morphologies. It is important to discern one from the other, since both have different remedial measures that are needed to prevent defect formation in the future. They almost have the exact same name, except for one small character: cold shuts and cold shots .