Ultrasonic characterization of burrs in aluminium pressure castings

There are always burrs in hollow castings. They are caused by the joining of the different streams of molden alloy and they can be areas of poor mechanical properties. Up to now, burrs are checked destructively using samples cut from the head and tail of the pressure casted product. It is found that the ultrasonic backscattering is suitable to visualize the fine grained microstructure of the seam area of the burr and the surrounding coarse grained area with higher content of impurities. The direction dependency of ultrasonic time-of-flight is used to characterize the crystallographic texture in the burr region. The texture is found to be different in the burr and in the adjacent areas and this difference changes along the length of the pressed part. The combination of ultrasonic backscattering and time-of-flight measurements is seen as a very promising nondestructive approach to characterize the burr and to determine the length of the pressure casted product with well developed mechani cal properties