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Home  >  Journal list  >  MATERIALS TRANSACTIONS  >  Vol.45  No.7 (2004)  >  pp.2403-2409

MATERIALS TRANSACTIONS
<<Previous article Vol.45  No.7 (2004)   pp.2403 - 2409 Next article>>

Nondestructive Detection of Cold Flakes in Aluminum Alloy Die-Cast Plate with Ultrasonic Measurement

Hiroshi Kato1), Tomoyuki Suzuki1), Yoshiharu Annou1) and Kensuke Kageyama1)
1) Department of Mechanical Engineering, Faculty of Engineering, Saitama University

Aluminum alloy die-cast plates (ADC 12) were subjected to ultrasonic measurement to obtain a relation between the intensity distribution of the ultrasonic wave and positions of cold flakes appearing in the plate for developing a nondestructive method to detect cold flakes in the die-casts. Die-cast plates of 170 mm in length, 50 mm in width and 6.8 mm in thickness were produced with wider gates to introduce larger cold flakes in the plate. Then the ultrasonic measurement was carried out with the immersion method by using a probe generating a longitudinal wave of 20 MHz in frequency. Intensity distributions of the ultrasonic wave were obtained from the surface to the bottom. The cross section analysis was carried out to examine the distribution of the cold flake. From the cross section analysis, three types of cold flakes were observed: the type A with a straight boundary of initial solidification with oxide thin layer, the type B with a straight boundary without oxide layer, and the type C of an irregular and wavy boundary without oxide layer. In the case of the type C, the oxide layer was thought to be out of the observed section. The ultrasonic wave was slightly reflected from the front and rear boundaries between the cold flake and the matrix, and it was found that the position and the thickness of the cold flake can be detected by ultrasonic measurement.


Keyword:
nondestructive testing, ultrasonic testing, die-castings, aluminum alloy, casting defect, cold flakes, ultrasonic wave, backscattered wave

Received: February 06, 2004
Accepted: May 21, 2004 , Published online: June 24, 2005
Copyright (c) 2005 The Japan Institute of Metals

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