Ultrasonic Inspections of Castings
Many advances in ultrasonic inspections of castings have led to the widespread application of ultrasonic scans to detect shrinkage, porosity, cracks, and other defects deep within castings. The simplest type of ultrasonic inspection, ultrasonic waves are initiated at the surface by a high-frequency transducer, they reflect from defects or from the rear surface of the casting and are picked up by the transducer. A plot of the amplified reflected waves on a CRT shows the presence of defects within the casting. More sophisticated ultrasonic testing techniques involve immersion of the casting in a water bath enhancing the pickup of the ultrasonic waves to provide a two-dimensional map of the defects present. These techniques are applied to a wide variety of both sand and investment castings.
Ultrasonic inspections of castings is covered in ASTM specifications:
- ASTM E 114
- ASTM E 587
- ASTM E 1001