Cause Analysis on Black Spots Detected by X-ray in a ZTA15 Titanium Alloy Investment Casting

Black spot suspected defect was found in a ZTA15 titanium alloy investment casting when X-ray detection. The causes of the black spot display were analyzed by coloring test, macro test, metallographic examination, hardness test and chemical composition analysis. The results show that the black spots displayed in X-ray detection were caused by the casting repairing welding microstructure, and were not casting defect.