GB2149915A - An improved method of ultrasonic inspection - Google Patents
An improved method of ultrasonic inspection Download PDFInfo
- Publication number
- GB2149915A GB2149915A GB08329268A GB8329268A GB2149915A GB 2149915 A GB2149915 A GB 2149915A GB 08329268 A GB08329268 A GB 08329268A GB 8329268 A GB8329268 A GB 8329268A GB 2149915 A GB2149915 A GB 2149915A
- Authority
- GB
- United Kingdom
- Prior art keywords
- signals
- crack
- austenitic
- application
- welds
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 238000007689 inspection Methods 0.000 title claims description 11
- 238000000034 method Methods 0.000 title claims description 10
- 239000000463 material Substances 0.000 claims abstract description 37
- 230000000694 effects Effects 0.000 claims abstract description 15
- 230000006835 compression Effects 0.000 claims description 10
- 238000007906 compression Methods 0.000 claims description 10
- 229910000963 austenitic stainless steel Inorganic materials 0.000 claims description 6
- 239000002184 metal Substances 0.000 claims description 6
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 4
- 239000007788 liquid Substances 0.000 claims description 4
- 230000007423 decrease Effects 0.000 claims description 2
- 230000007547 defect Effects 0.000 claims description 2
- 239000007789 gas Substances 0.000 claims description 2
- 238000011835 investigation Methods 0.000 claims description 2
- 229910052757 nitrogen Inorganic materials 0.000 claims description 2
- 238000005507 spraying Methods 0.000 claims description 2
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/44—Processing the detected response signal, e.g. electronic circuits specially adapted therefor
- G01N29/4409—Processing the detected response signal, e.g. electronic circuits specially adapted therefor by comparison
- G01N29/4436—Processing the detected response signal, e.g. electronic circuits specially adapted therefor by comparison with a reference signal
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/04—Analysing solids
- G01N29/06—Visualisation of the interior, e.g. acoustic microscopy
- G01N29/0609—Display arrangements, e.g. colour displays
- G01N29/0618—Display arrangements, e.g. colour displays synchronised with scanning, e.g. in real-time
- G01N29/0627—Cathode-ray tube displays
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/04—Analysing solids
- G01N29/11—Analysing solids by measuring attenuation of acoustic waves
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/44—Processing the detected response signal, e.g. electronic circuits specially adapted therefor
- G01N29/48—Processing the detected response signal, e.g. electronic circuits specially adapted therefor by amplitude comparison
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/04—Wave modes and trajectories
- G01N2291/044—Internal reflections (echoes), e.g. on walls or defects
Landscapes
- Physics & Mathematics (AREA)
- Analytical Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Signal Processing (AREA)
- Engineering & Computer Science (AREA)
- Acoustics & Sound (AREA)
- Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
Abstract
In the ultrasonic scanning of a material, a compressive stress is applied to the material. The reflected signals obtained during the application of the compressive stress are compared with the reflected signals obtained in the absence of such stress. A difference in the amplitude of the compared signals is indicative of the presence of a flaw in the material. The effect can be used to distinguish between signals resulting from cracks in austenitic welds and signals arising from the metallurgical structure of such welds, the latter being unaffected by the application of compressive stress, and the former being closed by the compressive stress.
Description
SPECIFICATION
An improved method of ultrasonic inspection
The present invention concerns the ultrasonic inspection of materials, in particular the ultrasonic inspection of austenitic stainless steel weldments.
The metallurgical structure of austenitic weldments interacts in a complex manner with ultrasonic waves resulting in ambiguity when interpreting reflections and possible misinterpretation of defect positions. Changes occur in the reflected signals resulting from flaws or cracks if compression forces are applied to a material under investigation. The effect results in a reduction in reflected signal amplitude as crack closure takes place.
The aim of the invention is to utilise this effect, termed the compression crack closure effect, to positively detect flaws and cracks in austenitic stainless steel materials.
According to the present invention a method of ultrasonic inspection comprises scanning a material under test ultrasonically, applying a compressive stress to the material, noting and comparing reflected signals obtained during the application of compressive stress with the reflected signals obtained in the absence of compressive stress, a difference in the amplitude of the compared signals being indicative of the presence of a flaw in the material.
The coarse and anistropic structure of austenitic weld metal results in a high level of spurious signals and high attenuation levels during ultrasonic inspection. The velocity of ultrasonic waves travelling through anistotropic structures of austenitic welds depends on the orientation of the ultrasonic beam with regard to the axes of the long columnar grains existing in such welds. A velocity maximum occurs at about 45 beam to grain angle and velocity minima occur when the ultrasonic beam is directed parallel and perpendicular to the grain axes. These variations affect the wave propagation in the welds and in general the direction of propagation is not normal to the wave front but deviates by a certain angle.
Such deviation or skewing can result in spurious signals. Spurious signals can also arise at the parent metal/weld metal interface.
The ultrasonic response from a crack or flaw is influenced by the application of compressive stresses on the faces of the crack and significant decreases in the amplitude of the reflected signals take place on the application of compressive stresses. This effect, the compression crack closure effect, can be used to distinguish between a true signal originating from a crack in an austenitic weld and false signals that are inherent due to the metallurgical structure of the welds. Tests have demonstrated that the compression crack closure effect has no influence on the false signals arising from the metallurgical structure of the welds Such false signals remain unaffected and are substantially the same with and without the application of compressive stresses to a material being tested.As the true signals arising from the crack are significantly reduced in amplitude upon the application of compressive stresses to the material it becomes possible to distinguish and identify the presence of a crack in the material. The application of compressive stresses in austenitic welds can be used as a discriminatory technique for the analysis of signals returning from any cracks existing in such welds. The compression crack closure effect manifests itself at low stress levels and can respond even at closure of a transverse crack in austenitic tubing running almost parallel to the ultrasonic sound beam propagation. The reflected signals can be displayed on a CRT screen, a first set of signals being obtained before the application of compressive stresses to the specimen being tested and a second set after the application of such stresses.The two sets of signals are compared to determine whether or not a crack or flaw exists in the material under test.
The compressive stresses can be generated in a number of ways and as example mention can be made of:
a. Mechanical means such as shaped vice jaws to fit the shape of a component under test.
b. Passing of hot liquids or gases through tubular products under test.
c. Spraying liquid nitrogen on the surfaces of a component under test.
An alternating load can be applied to the material under test to generate "flutter" in the reflected signals. For example, under the influence of an alternating load a mirror image of the signal envelope generated by a crack in the material under test alternates in step with the resonating load from a minimum value to a maximum value indicated by the original signal envelope. Thus, the original signal envelope remains constant with a mirror image oscillating therein. The oscillating signal is derived from the crack or flaw in the material under test. Background noise and other spurious signals displayed on the CRT do not exhibit an oscillating response or only to such a small extent as not to cause any difficulty in the interpretation of the displayed signals.
1. A method of inspecting austenitic stainless steel material which comprises scanning the material ultrasonically, applying a compressive stress to the material noting and comparing reflected signals obtained during the application of compressive stress with the reflected signals obtained in the absence of compressive stress, a difference in the ampli
**WARNING** end of DESC field may overlap start of CLMS **.
Claims (2)
1. A method of inspecting austenitic stainless steel material which comprises scanning the material ultrasonically, applying a compressive stress to the material noting and comparing reflected signals obtained during the application of compressive stress with the reflected signals obtained in the absence of compressive stress, a difference in the ampli tude of the compared signal being indicative of the presence of a flaw in the material.
2. A method of inspecting austenitic materials as claimed in claim 1 substantially as herein described.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08329268A GB2149915A (en) | 1983-11-02 | 1983-11-02 | An improved method of ultrasonic inspection |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08329268A GB2149915A (en) | 1983-11-02 | 1983-11-02 | An improved method of ultrasonic inspection |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8329268D0 GB8329268D0 (en) | 1983-12-07 |
| GB2149915A true GB2149915A (en) | 1985-06-19 |
Family
ID=10551115
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08329268A Withdrawn GB2149915A (en) | 1983-11-02 | 1983-11-02 | An improved method of ultrasonic inspection |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2149915A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4340669A1 (en) * | 1993-11-30 | 1995-06-01 | Uwe Dipl Ing Kuehsel | Testing the quality of longitudinal compression joints |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113804756B (en) * | 2020-06-11 | 2023-11-17 | 北京新科启源科技有限公司 | Rail defect real-time correction system and method |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1017061A (en) * | 1961-02-23 | 1966-01-12 | Central Electr Generat Board | Improvements in or relating to methods of detecting flaws in solid material and of apparatus therefor |
| GB1166427A (en) * | 1968-07-16 | 1969-10-08 | Ford Motor Co | Ultrasonic Testing of a Rubber to Metal Bond |
| GB1282812A (en) * | 1970-04-21 | 1972-07-26 | Friedrich Foerster | Method of detecting welds on inadequate strength in continuously welded tubes |
| GB1523295A (en) * | 1975-10-15 | 1978-08-31 | Shell Int Research | Method and apparatus for inspecting stratified material |
| GB2027544A (en) * | 1978-08-04 | 1980-02-20 | Euratom | Testing brazed metal joints |
| GB2138138A (en) * | 1983-04-13 | 1984-10-17 | Atomic Energy Authority Uk | Dynamic method for the detection of discontinuities in a body |
| GB2139026A (en) * | 1983-04-13 | 1984-10-31 | Atomic Energy Authority Uk | Signal processing |
-
1983
- 1983-11-02 GB GB08329268A patent/GB2149915A/en not_active Withdrawn
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1017061A (en) * | 1961-02-23 | 1966-01-12 | Central Electr Generat Board | Improvements in or relating to methods of detecting flaws in solid material and of apparatus therefor |
| GB1166427A (en) * | 1968-07-16 | 1969-10-08 | Ford Motor Co | Ultrasonic Testing of a Rubber to Metal Bond |
| GB1282812A (en) * | 1970-04-21 | 1972-07-26 | Friedrich Foerster | Method of detecting welds on inadequate strength in continuously welded tubes |
| GB1523295A (en) * | 1975-10-15 | 1978-08-31 | Shell Int Research | Method and apparatus for inspecting stratified material |
| GB2027544A (en) * | 1978-08-04 | 1980-02-20 | Euratom | Testing brazed metal joints |
| GB2138138A (en) * | 1983-04-13 | 1984-10-17 | Atomic Energy Authority Uk | Dynamic method for the detection of discontinuities in a body |
| GB2139026A (en) * | 1983-04-13 | 1984-10-31 | Atomic Energy Authority Uk | Signal processing |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4340669A1 (en) * | 1993-11-30 | 1995-06-01 | Uwe Dipl Ing Kuehsel | Testing the quality of longitudinal compression joints |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8329268D0 (en) | 1983-12-07 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |