Measuring and testing – Vibration – By mechanical waves
Patent
1997-06-17
2000-07-25
Williams, Hezron
Measuring and testing
Vibration
By mechanical waves
73599, G01N 2904
Patent
active
060924209
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an ultrasonic flaw detection apparatus and an ultrasonic flaw detection technique used for examining a weld or examining plate materials, tubing materials, etc.
More particularly, the present invention relates to a so-called ultrasonic angle-beam flaw detection technique which employs ultrasonic waves which advance at a slanted angle with respect to a test surface of an object to be examined. There is such a term as measurement which is distinguished from such a term as examination or detection; however, the term, measurement, herein is handled so that it is included in the term, examination or detection. Likewise, the term, examination results, include such terms as test results and flaw detection results.
BACKGROUND ART
Hitherto, this type of ultrasonic angle-beam flaw detection technique has been described in detail on, for example, pages 180 to 199 of "Ultrasonic Flaw Detection Technique (revised new publication)" edited by Steelmaking Committee No. 19, Japan Society for the Promotion of Science, published by THE NIKKAN KOGYO SHIMBUN LTD., a revised new edition thereof being published on Jul. 30, 1974 and the third impression of a revised new edition thereof being published on Dec. 20, 1977 (hereinafter referred to as "Literature A").
Referring to FIG. 80, conventional ultrasonic flaw detection apparatus and ultrasonic flaw detection technique will be described. FIG. 80 is a diagram illustrative of a conventional ultrasonic angle-beam flaw detection technique cited from the foregoing literature A.
In FIG. 80, a test object 1 has a base material member 2, a surface 3, a bottom 4, and a weld 5. An acoustically discontinued portion (defect) 6 is present in the weld 5 of the test object 1. The acoustically discontinued portion 6 comes in various types including a crack in a first pass weld at the time of welding, a crater crack at a welding start or end, defective fusion, poor penetration, slag contamination, a blowhole, a wormhole, a hot crack, and a difference in material from a peripheral medium due to foreign substance contamination. Further, the acoustically discontinued portions also include spots contaminated by foreign substances, cracks, flaws, etc. which already exist in materials themselves irrespective of the welding operation. For the purpose of simplicity, these acoustically discontinued portions will be referred to as the defect 6 in the following description. In the drawing, a probe 7 is rested on the surface 3 of the test object 1.
An ultrasonic pulse is transmitted into the test object 1 from the probe 7 placed on the surface 3 of the test object 1 which corresponds to a test surface. In the drawing, the propagating direction of the ultrasonic pulse is indicated by a solid line with arrows; an angle ".theta." denotes the refraction angle of the ultrasonic beam. An echo resulting from the irradiation to the defect 6 is reflected back and received by the probe 7.
The defect 6 is detected as follows. Although it is not shown, an ultrasonic flaw detector which is electrically connected to the probe 7 measures the difference between the time when the ultrasonic pulse is transmitted from the probe 7 and the time when the returning echo is received, that is, the time required for the ultrasonic pulse to propagate through the test object 1. The time required for the ultrasonic pulse to make a round trip between the probe 7 and the defect 6 is divided by two to determine the time required for one way, propagation and then the determined time for one way propagation and the one way velocity of sound in the test object 1 are used to acquire the beam path length. The beam path length is denoted by "Wy" in the drawing.
As shown in the drawing, if the thickness of the test object 1 is denoted by "t", then a horizontal distance "y" and a depth "d" from the surface 3 of the test object 1 to the defect 6 can be determined by equation 1 and equation 2 shown below.
Equation 2 for determining the depth d applies when the ultrasonic pulse transmitted from t
REFERENCES:
patent: 4497210 (1985-02-01), Uchida
patent: 4537073 (1985-08-01), Oshiro et al.
patent: 4597292 (1986-07-01), Fujii
patent: 4949310 (1990-08-01), Smith
patent: 4993416 (1991-02-01), Ophir
patent: 5524626 (1996-06-01), Liu
"Ultrasonic Flaw Detection Technique", published by Nikkon-Kogyo Newspaper on Dec. 20, 1977, publisher Hajima Takashiro, in Japanese.
Kameyama Shumpei
Kimura Tomonori
Koike Mitsuhiro
Manome Yuuichi
Wadaka Shusou
Kwok Helen C.
Mitsubishi Denki & Kabushiki Kaisha
Williams Hezron
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