It is known that ultrasonic testing of forgings by international and national standards are regulated, but in spite of that, especially, ultrasonic testing of heavy forgings presents very complex part of the ultrasonic testing of materials. The heavy forgings usually have the weight over 3, 000 kg and from large ingots are manufactured. In large ingots exist different porosities and inhomogeneous, which are distributed through vertical and cross-section of ingots. After manufacturing of ingots to forgings such state in modify form to a certain degree is stayed. Such phenomenons are manifested by strong segregations, non-metallic inclusions, contracted cavities, flakes etc. There are sections with different consistences in forgings. The zones have different acoustical impedances so that on their boundaries ultrasonic waves are reflected, transformed or go through materials with certain attenuation of waves. Besides, the path of ultrasonic waves through heavy forgings is long and pass through zone with different consistences as well. Namely, by interpretation of ultrasonic findings, except ultrasonic technique of examination, it is necessary to have higher degree of knowledge of technology and production of forgings.
All of above mentioned phenomena have influences on objective interpretations of ultrasonic findings i. e. the determination of nature and size of detected faults.
In this work is carried out following:
- Investigation of further possibilities of identification of faults by ultrasonic testing of heavy forgings and confirmation of findings with other methods (visual inspection, metallographic examination etc. )
- Establishment of types, intensities and distribution of discovered faults in heavy forgings i. e. ingots.
- Analyses of current methods of determination of size of discovered faults.
The investigations were carried out on heavy forgings from medium - carbon steel and in this work concrete examples are given. REFERENCES
- B. Sladojevic, "Ultrasonic Testing of materials", Belgrade, interqual, 1996 (the book is being printed)
- J. u. H. Krautkramer, "Werkstoffprufung mit Ultraschall", Berlin. Springer Verlag 1975
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