Ultrasonic testing for the internal quality evaluation of cast steel products

A new method has been developed for the inspection of internal quality of cast products. The ultrasonic measurement technique “HD scan” for the evaluation of internal quality defects in the cast product sample needs a less surface processing in comparison to the etching procedure. The clean and safe technology offers threedimensional views into the sample, providing higher representative information for a better quality evaluation. The quality evaluation is done automatically and based on clear statistical rules. Size and distribution of the segregation are used for a segregation classification. Cracks statistics and narrow side profile contour determination are being realized too. The accuracy of the new method is proved by parallel metallographic investigations. Automatic defect determination and classification is compared with macro-etching classification results on more than 100 samples of different cast products. Macrostructure visualization is possible even for samples that do not succeed by macroetching. Areas of equiaxed and columnar crystallization can be distinguished and quantitatively determined. All this is beneficial for the optimization of cast parameters, such as strand shell cooling, soft reduction or mold and strand stirring. The ultrasonic quality evaluation system offers reliable and objective quality results fully independent of etching parameters and subjective quality operator impressions. The hitherto existing etching method may be completely replaced or the number of etching tests will significantly be reduced. HD scan is a part of the HD family. HD stands for High Definition or the improvement of product quality via higher precision of the casting processes.