Adal Arasu*, K. G. Satyanarayana**, B. C. Pai**, R. M. Pillai** and S. Madavan* *QDMF, Vikram Sarabhai Space Centre, Thiruvananthapuram, Kerala, India ** Regional Research Laboratory, Thiruvananthapuram, Kerala, India
Keywords: Aluminum matrix; casting defects; clustering; attenuation; screening NDE tool
ABSTRACT
Cast Al based composites containing particulate of silicon carbide or alumina are being extensively studied in view of their unique characteristics and cost compared to those processed by powder metallurgy. But cast composites pose problems through castings defects as well as composite defects such as clustering, non-uniform distribution of dispersoids etc. A methodology using nondestructive testing technique (X-ray radiography and ultrasonic) for Al(6061/2024)-SiCp composites has been presented here which can be practised industrially to screen the cast composite ingots/products in respect of their soundness, distribution of dispersoids etc. The ultrasonic test results obtained on statistical analysis revealed (I) a small difference in the attenuation, velocity and metal noise between as cast and fully heat treated composite ingots suggested a low levels of locked in stresses in the cast composites, (ii) the local imperfection in the composites ingots appeared as a result of the changes in the local solidification condition and also due to the presence of the dispersoids. These were detected easily by ultrasonic but the same was not possible through X-ray radiography. These results clearly suggest that ultrasonic test can be used as a powerful NDE tool for screening the cast metal matrix composites and their products.
Publication Source: Trends in NDE Science & Technology; Proceedings of the 14th World Conference on Non-Destructive Testing, New Delhi, 8-13 December 1996.Vol. 2, pages 743 - 746 Publisher:Ashgate Publishing Company
NDTnet
