CA1070007A - Method and device for the nondestructive testing of materials by means of ultrasonic waves - Google Patents
Method and device for the nondestructive testing of materials by means of ultrasonic wavesInfo
- Publication number
- CA1070007A CA1070007A CA243,596A CA243596A CA1070007A CA 1070007 A CA1070007 A CA 1070007A CA 243596 A CA243596 A CA 243596A CA 1070007 A CA1070007 A CA 1070007A
- Authority
- CA
- Canada
- Prior art keywords
- waves
- test piece
- displacement
- scattered
- probe
- 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.)
- Expired
Links
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
- G01N29/04—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
-
- 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
- G01N29/22—Details, e.g. general constructional or apparatus details
- G01N29/26—Arrangements for orientation or scanning by relative movement of the head and the sensor
- G01N29/265—Arrangements for orientation or scanning by relative movement of the head and the sensor by moving the sensor relative to a stationary material
-
- 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
- G01N2291/02—Indexing codes associated with the analysed material
- G01N2291/023—Solids
- G01N2291/0234—Metals, e.g. steel
-
- 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
- G01N2291/02—Indexing codes associated with the analysed material
- G01N2291/028—Material parameters
- G01N2291/02854—Length, thickness
-
- 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
- G01N2291/042—Wave modes
- G01N2291/0421—Longitudinal waves
-
- 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
- G01N2291/042—Wave modes
- G01N2291/0422—Shear waves, transverse waves, horizontally polarised waves
Landscapes
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Acoustics & Sound (AREA)
- Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
Abstract
A METHOD AND DEVICE FOR THE NONDESTRUCTIVE TESTING
OF MATERIALS BY MEANS OF ULTRASONIC WAVES
Abstract of the Disclosure An incident beam of ultrasonic waves is directed onto the surface of a test piece for nondestructive testing and especially for measuring the case-hardening depth of steels. The method consists in subjecting the beam to a uniform displacement at a constant angle of incidence, in detecting the ultrasonic waves back-scattered from the test piece, then in visualizing on a receiver the energies of the successive waves which are back-scattered during at least a predetermined fraction of the beam travel.
OF MATERIALS BY MEANS OF ULTRASONIC WAVES
Abstract of the Disclosure An incident beam of ultrasonic waves is directed onto the surface of a test piece for nondestructive testing and especially for measuring the case-hardening depth of steels. The method consists in subjecting the beam to a uniform displacement at a constant angle of incidence, in detecting the ultrasonic waves back-scattered from the test piece, then in visualizing on a receiver the energies of the successive waves which are back-scattered during at least a predetermined fraction of the beam travel.
Description
This invention rela-tes -to -the nondestructive -testing of materials by means of ul-trasonic waves and is clirected to a method Eor detecting and locating nonhomogeneous areas in a solid part. A particularly advantageous although non-limitative application of -the method consists in measuring -the hardening depth of steel par-ts. The invention is also concerned with a device of suitable desi~n for carrying out said method.
In the techniques of nondestructive testing of materials, known methods already utilize the phenomena of scattering of ultrasonic waves in materials. Especially in the case of steel parts, these methods make it possible to detect and locate structural variations resulting from a heat treatment.
One conventional method consists in directing an incident beam of ultrasonic waves onto the surface of a part to be tested, in displacing said beam progressively along the part and in observing the ultrasonic waves or echos which are back-scattered from the part in respect of different success-ive positions of the beam during displacement of this latter.
Broadly speaking, known methods have the disadvantage of supplying information whlch cannot readily be utilized under time conditions which are compatible with industrial testing operations. Difficulties arise in particular from the fact that no solution has yet been found for reconciling the contradictory but essential requirements of rapidity and precision, the amount of ultrasonic energy which is back-scattered being liable to ~ary as much as the grain distribu-tion in the part under inspection.
The present invention serves to facilitate non-destructive testing of materials by means of ultrasonic waves .
In the techniques of nondestructive testing of materials, known methods already utilize the phenomena of scattering of ultrasonic waves in materials. Especially in the case of steel parts, these methods make it possible to detect and locate structural variations resulting from a heat treatment.
One conventional method consists in directing an incident beam of ultrasonic waves onto the surface of a part to be tested, in displacing said beam progressively along the part and in observing the ultrasonic waves or echos which are back-scattered from the part in respect of different success-ive positions of the beam during displacement of this latter.
Broadly speaking, known methods have the disadvantage of supplying information whlch cannot readily be utilized under time conditions which are compatible with industrial testing operations. Difficulties arise in particular from the fact that no solution has yet been found for reconciling the contradictory but essential requirements of rapidity and precision, the amount of ultrasonic energy which is back-scattered being liable to ~ary as much as the grain distribu-tion in the part under inspection.
The present invention serves to facilitate non-destructive testing of materials by means of ultrasonic waves .
-2--' - ' ' : - : ' '' and to make the techni~ue readily accessible Eor :induskrial utilization.
The invention is directed to a method of non-destructive testing of materials which makes it possible in particular to measure the depth of hardening of steel and : essentially consists in directing an incident beam of ultra-sonic waves onto the surface of a test piece, in carrying out a uniform displacement of the beam over the test piece at a constant angle of incidence, in detecting the ultrasonic waves back-scattered by the test piece and in visualizing on a single receiver the energies of the successive waves which are back-scattered during at least a predetermined fraction of said displacement.
Preferably, the beam of ultrasonic waves is directed onto the test piece at a constant oblique angle of incidence in order to prevent the back-scattered waves from being masked by the high-energy echo caused by the reflection of the waves from the surface of the test piece. The angle of incidence is advantageously larger than that which corresponds to the ~0 critical reflection of the longitudinal waves in order to -ensure that only one beam of transverse waves is refracted within the test piece. Especially in the case in which the transmission of waves to the test piece takes place in water, the angle of incidence is preferably of the order of 15 to 25.
. 25 In accordance with the invention, it is an advantage to combine a local periodic displacement of the beam in the vicinity of a mean point with a continuous displacement of the mean point on the test piece. It is thus possi~le in particular to combine a longitudinal movement of translation at constant speed with a transverse reciprocating movement of translation or with a continuous movement of rotation which _3_ ~`- - '- :'-. - .......... . .
- - :
, is centered on the mean point such as a movement of conical revolution of a beam havin~ an oblique angle of incidence.
These movements are preferably carr.ied out at constant speed.
In conjunction with the longiludinal displacement of the beam~ it is an advantage to have recourse to a particular mode of visual display of the energies of the back-scattered waves whereby the energies which exceed a predetermined threshold value are visualized on a screen as a function of the longitudinal displacement. It is possible in particular to employ the screen of a storage cathode-ray tube and to control the spot deflection plates respectively by means of a volta~e which is proportional to the longitudinal displacement of the incident beam and by means of the time base of the incident waves by modulating the intensity of the spot by means of the energy of the detected back-scattered waves.
However, the invention does not exclude the use of other modes of visualization entailing the need for observa-tion in stages along the surface of the test piece. In particular, the variations in energy of the back-scattered waves during a local periodic displacement of the incident beam can be recorded on a single visual display screen, for example by photographing the screen of a cathode-ray tube.
In this case, said displacement is preferably obtained by means of a conical movement of revolution of the beam at constant speed.
The invention is also concerned with a device for : nondestructive testing of materials in which said device essentially comprises means for emitting an incident beam of ultrasonic wave trains, means for orienting sa.id beam at an oblique angle of incidence with respect to the surfac2 of a .
' - ~ . '' ~ ' "' ' "
~ - '- ' ~ ', ' .
~L~7~
test piece, means for detec-ting waves wh:Lch are back-scattered by said test piece and preferably a-t the same angle, sa.id detection means being provided if necessary with the same transducer as the emission means, and means for dis~
placing the beam with respect to -the -test piece and maintain-ing constant the angle of incidence and the len~th of the acoustic path between the emission means and the sur~ace of said test piece.
: Preferably, an emi.tting and/or receiving ultrasonic transducer is mounted within a leak-tight apparatus closed by a window in contact with the test piece and Eilled with an acoustic couplant liquid such as water at least over the enti.re acoustic path between the transducer and the window.
The apparatus advantageously contains not only the .
transducer but also beam-orienting means constituted especially by at least one reflecting mirror and/or means for local dis-placement of the beam especially by tran~lational or rotational -:
motion of the reflecting mirror and/or the transducer.
In one of the preferred embodiments of the device, the transducer is mounted within a slide tube which is capable of translational motion within the apparatus in a direction parallel to the window. The beam is emitted in an oblique direction through the window by the transducer which is oriented in this direction or by an acoustic mirror : 25 which i5 also mounted on the slide tube if the transducer cannot be oriented in this direction. The slide tube can be displaced in a reciprocating movement of translation either by hand or preferably by means of an electric motor and a cam against which the extremity of the slide tube is maintained applied by means of a spring.
In another preferred embodiment of the cLevice, the - , . .
.. .
-, ~7V~
apparatus comprises a movable -transducer mounted on a movable member designed to carry out a conical movement of revolution of the beam produced by the -transducer which is oriented at an oblique angle towards a point of the surface of the test piece through -the window of the apparatus, or a stationary transducer having an axis at right angles to the test piece and a rotating system of reflecting mirrors for carrying out the conical movement of revolu-tion of the beam at an oblique angle towards a point of the surface of the test piece through the window of the apparatus.
A more complete understanding of the invention will be gained from the following description and from a study of the accompanying drawings in which a few Pmbodiments of the method and the device according to the present invention are illustrated solely by way of example, and in which :
- Fig. 1 shows diagrammatically a first alternative emhodiment of a device in accordance with the invention ;
- Fi~. 2 shows diagrammatically a second alternative embodiment of the device ;
~ Fig. 3 shows a mode of displacement and a type of visual display obtained by means of the alternative embodiment of Fig. 1 ;
- Fig. 4A shows a mode of displacement and a type of visual aisplay obtained hy means of the alternative embodiment of ~ig. 2 ;
Fig~ ~B ~hows a mode of composite displacement obtained b~ means o~ t~e alternative embodiment of ~ig. 2 and a corresponding type of visual display , - Fig. 5 is a longitudinal sectional view showing an apparatus according to the invention in which the beam is displaced in translational motion ;
.
.~ . . - - . -" - ' ' ' ~ ' ' "' , . .
~7~
- Fig. 6 is a transverse sec-tional view showing the apparatus of Fig. 5 ;
- Fig. 7 is a diagrammatic view showing an assembly which is employed for adjusting the apparatus ;
- Fig. 8 is a partial longitudinal sectional view showing an apparatus according to the invention in which the beam is displaced in rotational motion ;
- Fig. 9 is a longitudinal sectional view showing an apparatus according to the invention with translational displacement and an integrated displacement pickup ;
- Fig. 10 is a longitudinal sectional view showing another apparatus in accordance with the invention comprising an integrated displacement pickup in the case of displacement in rotational motion.
In its application to the measurement of hardness penetration of steel parts, the method according to the invention is based on the observation of ul-trasonic waves scattered by the part and more precisely on the observation of variations in energy of the ultrasonic waves which are scattered backwards by the grains of the material after attenuation by these latter within the thickness of the part.
In fact, it is already known that in the case of a given part corresponding to a predetermined mean volume of initial austenite grains of the steel (prior to heat treatment), scattering of the ultrasonic waves is much w~aker in a martensitic structure as obtained by rapid cooling of steel than in a pearlitic structure as obtained by slow cooling.
The degree of scattering is of intermediate value in the case of stru~tures obtained with an intermediate cool:ing rate~
~owevex, the difference in scattering is usually sufficiently well defined between the hardened steel layer and the - -~ -.
unhardened portion to permit determination of the depth oE
the hardene~ layer, especially in the case of substantial hardness penetrations obtained or example by high-frequency treatment.
The me-thod according to the invention makes it possible to observe this difference by making use of particularly convenient means for establishing a mean value of back-scattered energies over a predetermined fraction of surface of the test piece and to measure directly in a receiver for the visuali~ation of said energies the distance between the surface of the test piece and the depth limit of the hardened layer.
In the practical application of the invention, preference is given to the use of a single transducer or ultrasonic probe for emitting ultrasonic wave trains constit-uting the incident beam which is directed onto the test piece and for detecting the ultrasonic waves back-scattered by the piece, or echos. However, in other forms of applica-tion, the emission and detection can be carried out by means of different probes. ~ ~
The different examples of device which will be -described hereinafter all entail the use of a single probe.
Moreover, said probe is inclined or combined with suitable -.
devices so as to direct the beam of ultrasonic waves at an ~5 oblique angle of incidence onto the test piece and this angle of incidence remains constant during a ~isplacement to which the beam is subjected with respect to the surface of the test plece while also maintaining constant the length of the ; acoustic path between the probe and the test pieceO
By virtue of the means which will be described later, the beam is subjected to a local periodic displacement at a . . - , .
.. .
~7~
uniform speed which can b~ ei-ther a reciproca-tin~ movem~nt of translation or a continuous movement of rotation. This local displacement is combined in some cases with a disp]ace-ment of the mean point of the local displacement, which can be either non-con-tinuous or continuous at a constant, low speed with respect -to the local displacement.
The inclination of the angle of incidence of the beam offers a number of advantages. In the first place, the high-amplitude echo produced by reflection from the surface of the test piece can thus be removed from the detection. Said inclination also makes it possible in the case of an an~le of incidence which is greater than the an~le of incidence corresponding to the critical reflection of the longitudinal waves to ensure that the transverse waves which have the advantage of much lower velocity than longitudinal waves are alone refracted within the test piece. Moreover, the fact that the refracted beam is inclined increases the length of the wave path within the thickness of the part being tested.
The devices which are shown diagrammatically in the general views of Figs. 1 and 2 differ from each other in the mode of visualization of the energies of the back-scattered waves.
The device of Fig. 1 essentially comprises a wave-train generator 1 which controls the emission of the probe 7.
Said probe produces a beam to which is imparted a periodic local movement a~ove a test-piece holder 9 by mechanical means which will be described hereinafter. In the ca~e of treatment of si~nals corresponding to the back-scattered waves detected by the probe 7~ the device comprises in series an amplifier 2, a filter 3 and a detection unit 4 A visual display of the si~nals is produced on the screen of a cathode-ray tube 5. The _g _ , .
amplitude of the echos detected con-trols the vertical deflection plates of the cathode-ray tuhe whilst a tirne base 6 controls the horizontal deflection plates. It is thus possible to obtain aEter adjustment of the time base in synchronism with the emission of the incident beam a repre-sentation of the variations in energy E of the echos as a function of the distance D travelled by the ultrasonic waves within the material.
In the case in which a part of hardened steel is thus subjected to testing, the image is of the type shown in Fig. 3. The device is advantageously provided in addition with a camera which serves to record the energy curves visualized on the screen of the cathode-ray tube throughout the duration of the local displacement of the probe and thus to display the mean curve of the energ~ scattered over a ; narrow integration range which is dependent on the amplitude of displacement of the probe. The thickness of the hardened steel layer cor~esponds to the distance between the first two .
echos of high amplitude ~H in ~ig. 3).
The device of Fig. 1 has a disadvantage in that it ..
provides the information in deferred time since it entails the superimposition of a plurality of successive images without permitting a geographlcal representation, the observed result being a mean value between a number o~ points of the test ~5 piece.
The device shown in Fig. 2 circumvents these dis-advantages and makes it possible in particular to establish in real time a geoyraphical representation of the thickness o~ the hardened layer o~ a steel part. As in the previous case, this device comprises an ultrasonic wave-train generator 1, the probe 7 which is capable of moving in a direction ~ -' " '. . ; ,.,~ : ' ' ~
~o~
parallel to a test-piece holder 9, an amplifier 2, a fil~er 3, a detection unit ~, a cathocle-ray tube 5 and a -time base G.
'~he device differs from the previous embodiment in that the local displacement of -the probe or even the complete dis-placement of the apparatus if necessary is measured at eachinstant by means of an electrical device 8 which can be a linear or rotational displacement pickup.
The voltage delivered by the device is proportional to the displacement of the probe and controls the horizontal deflection plates of the cathode-ray tube 5. The time base 6 controls the vertical de~lection plates in synchronism with the emission of the incident beam whilst the detected signals whose amplitude is characteristic of the back-scattered energy are employed for modulating the light intensity of the spot of the cathode-ray tube. There is thus obtained direGtly on the screen of the cathode-ray tube a yeographical representa-tion o~ the origln of the echos within the thickness of the test piece as a function of the measured displacement of the probe as shown in Figs. 4A and 4B which show the variations in depth H of the hardened layer.
There will now be described in a number of different embodiments the constr~ction of the mechanical portion o~
the device according to the invention at the level of the ultrasonic probe and means for displacing the beam.
In these different alternative embodiments, a single txansducer carries out the emission of the incident beam of ultrasonic wave trains and the reception of the waves which are back-scattered by the test piece. Said transducer is mounted with means for orienting and displacing the beam within the interior of a leak-tight apparatus filled ~ith a liquid which provides acoustic couplill~ between ~ '~ . - -,, ~ - -- .
-. ~ ~ ' - 11 , :
- .
.. ..
, the transducer and the test piece and consists ~spec:ially oE
water.
In each case, said leak-tight apparatus is closed by a window which permits transmission of the ultrasonic S waves between the transducer or ultrasonic probe and the surface of the test piece, the liquid beinc~ retained by a thin flexible diaphragm which is transparent to ultrasonic waves and placed over the window. Supporting and/or fixing members serve to place the apparatus in position with the flexible diaphragm applied in contact with the surface of the test piece.
The ultrasonic beam can be directed obliquely towards the window in order to obtain an oblique angle of incidence which can be adjusted if necessary either by inclinin~ the probe itself or by making use of systems for reflecting the beam.
Local displacement of the beam can be obtained by imparting a suitable movement to the probe or to reflecting systems within the apparatus ; this can be carried out either by hand or by means of a motor. This local displacement can consist especially of a periodic movement of translation or of rotation, thus making it possible to adopt either a mode of visualization in accordance with Fig. 3 or a mode of visualization in accordance with Fig. 4A as requirements dictate. In addition, however, the apparatus itself can be j displaced if necessary over the surface of the test piece in order to carry out a composite mode of displacement of the beam, thus permitting a mode of visualization i~ accordance with Fi~. 4B~
The apparatus shown in Figs. 5 and 6 permits rectilinear displacement o the probe and of a re:Electin~
- .. '-., ' - `- ' - . , - ' ,, . ' 7~7 mirror which ensures orierltation of -the beam. The ~pparatus may be employed exactly as shown in the arrangement of Fig. 1 with a mode of rectilinear translational displacemen-t and a mode of visualization in accordance with Fig. 3. The apparatus can also comprise an additional external displac~ment pickup (of the wire type, for example) and can be employed in the arrangement of Fig. 2 with a composi-te mode of displacemen-t consisting of two perpendicular movements of translation and a mode of visualization in accordance with Fig. 4B.
The probe 40 and the mirror 43 are mounted within a hollow cylindrical slide tube 42 which is in turn mounted so as to be capable of translational motion in the axis of the ; cylindrical shell 41 of the apparatus. This latter also contains a reduction-gear motor 23, the output shaft of which is mounted in the axis of the slide tube and carries a cam 49 against which is applied the extremity of the slide tube 42 by means of an antifriction bearing 24. The probe 40 is locked ; within the slide tube 42 by means of a piIl 48 which is screwed in position at the end of this latter ; said pin serves to support the bearing 24. The reflecting mirror 43 is p]aced opposite to the probe within the slide tube and fastened by means of a transverse locking-pin 37 which permits removal and replacement of said mirror. A third member 12 is screwed into the end of the slide tube. Said member has a blind-end bore for accommodating a spring 38 which is applied against the end-wal] 13 of the apparatus and thus urges the moving system against the cam 49. The end portion of the shell 41 is closed by a member 46 which is fixed in position by means of screws 34 and also has the design function of maintaining the spring-supporting end-wall 13.
Fine guiding of the slide tube is carried out by ;
- ..
~ -13-. -.
7~
means of bronze bearing-bushes 17 which are rigidly Eixed to the shell 41 and by means of anti~riction bearings 27 which not only serve to guide the moving system but also to prevent rotation of this latter about its axis. Said bearings are accordingly supported within a longitud:inal groove 21 formed within the bore of the shell 41. The cross-pins 22 which support the bearings 27 are displaced off-center and the positioning of these latter serves to adjust the clearance between the moving system and the shell. Screws 37 serve to lock the cross-pins 22 in position.
The apparatus is designed to be ~illed in the central portion thereof with a liquid which ensures acoustic coupling between the probe and the surface of the test piece.
; Leak-tightness of the chamber which contains the liquid is achieved :
- opposite to the openlng of the shell by means of a thin flexible diaphragm ll which is transparent to ultrasonic waves, said diaphragm being held in position by means of a retaining ring 45 which is clamped against a recessed diaphragm support 44 which limits the window ;
- between the shell and the slide tube by means of lipped seals 25 ;
- between the probe and the slide tube and between the bearing member of the spring 38 and the slide tube by means of 0-ring seals 26 fitted within grooves which are machined in the slide tube.
Filling o~ the chamber is carried out through an opening formed in the shell which is closed by means of a threaded plug 33 fitted with a seal 32. The chamber can be put under pressure by screwing the member 12 into the slide tube, this being accomplished by employing the key 14 which is ;--.. ;-,- ~ - ., ' , placed across -the slots Eormed in the end--wall 13.
The slide tube is pierced by an opening at the level of the probe through which are passed the leads for supplying current to this latter. The leads are soldered to a socket-outlet connector which is fixed on the external wall of theshell. There is placed at the end of the shell ~1 a right-angled member 47, one portion of which is cut out on one side so as to form a fork which serves as a support for fixing the apparatus on the parts to be tested. Said member ~7 is fixed in position by passing a screw 39 through a slot which permits of height adjustment.
The mirror 43 may be dispensed with if necessary if, in an alternative form of the preceding embodiment, the probe 40 is modified so as to ensure that the sensitive piezoelectric element is inclined at a sharp angle to the axis of the slide tube and placed opposite to the window of the apparatus.
Moreover, the mirror 43 can be replaced by a system 30 of complementary mirrors which is illustrated in Fig. 7.
This system serves to adjust the orientation of the plane of incidence of waves at right angles with respect to the surface of the test piece or with respect to the surface which is tangent to the surface of the test piece 31. The complementary mirrors are oriented so as -to return a fraction o~ the energy reflected from the surface of the test piece to the emitting~
receiving probe 40. The adjustment is carried out by determin-ing the orientation in which the reflected enexgy received by the probe is of maximum value. Since the distance travelled by the reflected waves is greater than the distance travelled 30 by the scattered waves, the respective echos are per ectly separated when they are received on the viewing screen.
- ~ -- - - -.......
- : -~1~37~
In the apparat7~s of Fig. 8, a local displacement ofthe incident beam of ultrasonic waves is carried out by means of a conical movement of revolution oE the beam.
Said apparatus can be employed in par-ticular exactly as shown in the arranyement of Fig. 1 with a mode of displacement in rotation and a mode of visualization in accordance with Fig. 3. The apparatus can also be associated with an additional ex-ternal displacement pickup (oE the wire type, for example) in order to be employed in the arrangement of Fi~. 2 with a composite mode of displacement of the beam, ; in local rotational motion and in translational motion, in conjunction with a mode of visualization in accordance with Fig. 4B.
The probe 50 is placed in the axis of a leak-tight ; 15 cylindrical shell 51 which terminates in a frusto-conical portion 53 (the bottom portion shown in Fig. 8) comprising a window which is perpendicular to the axis.
A rotating system comprising two mirrors for reflecting the beam emitted by the probe is mounted in front of this latter. A first mirror which is oriented at 45 degrees to the axis of the probe reflects the beam radially ; then a second mirror reflects said beam at an oblique angle with respect to the axis towards the window of the apparatus. These two mirrors are machined respectively in two steel members 57 and 56, these latter being assembled so as to form a circular component which is mounted in a bored cylindrical support 520 The support 52 is fixed on the rotor of a motor ~`
65 having a hollow shaEt, the probe 50 being located in the axis of sald motor. This moving system is centered in the cylindrical shell 51 by means of an antifriction bearing 66 which ensures the necPssary mobility without play.
~g7(~
The apparatus is deslgned to be filled with a liquid which ensures acoustic coupling between -the probe and the test piece ; leak-tightness is ensured :
- at the level of the window by a thin flexible diaphragm 55 which is transparent to ultrasonic waves and held in posi-tion by a clamp 54 ;
- between the probe and the shell by an 0-ring seal 64 which is compressed by means of a nut 58.
Pressurization of the liquid in order to cause deformation of the diaphragm is carried out by downward displacement of the probe within the apparatus, locking being obtained by tightening the nut 58.
The apparatus shown in Fig. 9 permits rectilinear translational displacement of the emitting-receiving probe.
This apparatus differs from that shown in Figs. 5 and 6 in the fact that it comprises a device for measuring the dis-placement of the integrated probe. Said apparatus is advan~-ageously employed exactly as shown in the arranyement of Fig. 2 with `a mode of translational displacement and a mode of visualization in accordance with Fig. 4A.
The probe 67 which is designed so as to ensure that the sensitive piezoelectric element is steeply inclined to the axis of the apparatus so as to emit the acoustic waves at an oblique angle is mounted within the interior of a hollow cylindrical slide tube 68 which is capable of moving within a cylindrical shell 69. The slide tube 68 is actuated manually by means of a member 70 on which it is engaged and maintained by means of a locking-pin 71. A hollow cross-pin 72 fixed in the shell 69 passes through a double slot formed in the op~rating member 70 and thus makes it possible to prevent the assembly of members 67, 68 and 70 from rotating about the axis . -. -: . .. :
.
~1~)7q~ 37 of the apparatus.
The displacement o -the men~ers 67, 68 and 70 in linear translational motion is measured by means of a displace-ment pickup 73 which is keyed i.n the mell~er 70 by means of an end-cap 74. The movable pin of the displacement plckup is : rigidly fixed to the shell of the apparatus which serves as a reference in the positioning of the members 67, 68 and 70 : by virtue of a locking-pin 75.
An opening formed in the slide tube 68 and the shell 69 provides a passageway for the acoustic beam produced by the probe ; the orientation of this latter is fixed by means of a pin 76.
The apparatus is designed to be filled in the central portion thereof with a liquid whi.ch ensures acoustic ` 15 coupling between the probe and the surface of the test piece. ~ .
; Leak-tightness of the chamber which contains the liquid is . ensured :
- opposite to the opening of the shell and of the slide tube by a thin flexible diaphragm 77 which is transparent to ultrasonic waves and held in position by a retaining ring 78 which is clamped against a recessed diaphragm support limited by the window ;
- between the shell and the slide tube and between the probe : and the slide tube by means of 0-ring seals 790 2S Filling of the chamber is carried out from the slide tube extremity which is closed by means of a threaded plug 80 ;
the greater or lesser engagement of this latter makes it . possible to adjust the pressure within thP.chamber and con-sequently the deformation of the flexible diaphragm 77.
El2ctrica1 connection o the probe is ensured by a connector : 81 from which leads 82 extend to a socket-outlet 83 which is 18- .
. . ... .
.. - -, - ' , - ' ' -. :
also provided with -terminals joined to the leads Erom the displacement pickup.
Provision is made Eor bearing members 8~ which permit suitable positioning of the apparatus on the surface of the part to be tested.
In the apparatus of Fig. lOr a local displacement of the incident beam of ultrasonic waves is carriecl out by means of a conical movement of revolution of the beam. This apparatus differs from that shown in Fig. 8 essentially in the fact that it comprises a device for measurin~ the displace-ment o~ the integrated probe. Said apparatus is advantageously employed exactly as shown in the arrangement of Fig. 2 with a mode of displacement in rotational motion and a mode of visualization in accordance with Fig. 4A.
The probe 85 is maintained by means of screws 87 in an oblique position within an eccentric hole formed in a probe-holder 86 consisting of a cylindrical member o~ revolu-tion. The probe-holder is mounted within a hollow shell constituted by two sections 88 and 89 which are assembled together by means o~ screws 90. A ball-bearing 91 serves to support the probe-holder an~ this latter can accordingly be subjected within the apparatus to a movement of rotation about its axis. In consequence, a conical movement of revolution about the axis o~ the apparatus can be imparted to the 2~ acoustic beam produced by the probe.
The movement of the probe 85 and of the probe-holder 86 is controlled by a knurled ~nob 92 located outside ~he shell and secured by means of a screw 93 to the shaft o~
a potentiometer 9~ which is ~i~ed on the cover of -the apparatus.
The apparatus is designed to be partly filled wi-th a - " ' ' ' ' "
-19- ~ ~
, - .
. ~ . . - . : . : :
liquid whi.ch provides acoustic coupling between the probe and the test piece ; leak-tightness is ensu:red :
- at the level of the window by a thin diaphragm 96 which is transparent to ultrasonic waves and held in position by a retaining ring 97 and an 0-ring seal 98 ;
- at the level of the assembly of the two sections 88 and 89 which constitute the shell of the apparatus by means of a seal 99 ;
~ at the level of the axis of the probe-holder ~6 and of the top portion of the shell 89 by means of a lipped seal lO0. ..
In order to produce the deformation of the diaphragm, the liquid is put under pressure by means of a piston constit-uted by an assembly of components and seals 101 to 106, the position of which is defined by rotating the member 104. -The probe 85 and the potentiometer 94 are connected electrically, respectively to socket-outlets 107 and 108 which are fixed on the shell of the apparatus.
Within the field of application to the measurement of hardness penetration in steel parts/ the apparatuses described are utilized to advantage by adopting ultrasonic-wave frequencies within the range of 5 to 20 Mc/s with wave-train repetition fre~uencies of 2 kc/s, for example. In order to permit direct reading of the hardness penetration, calibra tion of the visual display and more precisely of the time base ~5 of the cathode-ray tu~e can be carried out by seekin~ to obtain multiple echos of longitudinal waves in a Shim of known thickne~s. If the measurements are then performed with : different angles of incidence of the beam,. it is only . ~.
n~cessary to apply a corrective coefficient to the result determined in accordance with the preliminary calibration.
: By way of example, this coefficient is respectively 0.~ ;
' ~ , ' ' ' ' . -.20-. . .
,:
0.35 ; 0.3 in the case of angles of incidence of 18.5 ; 21 ;
or 23 degrees when the couplant liquid is water.
It is readily apparent that the invention is not limited in any sense to the embodiments which have been described in the foregoin~ with reference to the accompanying drawings. Depending on the applications which are contem-plated, consideration can be given to many possible alter-native forms which are accessible to any one versed in the art witho~lt thereby departing either from the scope or the spirit of the invention.
.
. - :
The invention is directed to a method of non-destructive testing of materials which makes it possible in particular to measure the depth of hardening of steel and : essentially consists in directing an incident beam of ultra-sonic waves onto the surface of a test piece, in carrying out a uniform displacement of the beam over the test piece at a constant angle of incidence, in detecting the ultrasonic waves back-scattered by the test piece and in visualizing on a single receiver the energies of the successive waves which are back-scattered during at least a predetermined fraction of said displacement.
Preferably, the beam of ultrasonic waves is directed onto the test piece at a constant oblique angle of incidence in order to prevent the back-scattered waves from being masked by the high-energy echo caused by the reflection of the waves from the surface of the test piece. The angle of incidence is advantageously larger than that which corresponds to the ~0 critical reflection of the longitudinal waves in order to -ensure that only one beam of transverse waves is refracted within the test piece. Especially in the case in which the transmission of waves to the test piece takes place in water, the angle of incidence is preferably of the order of 15 to 25.
. 25 In accordance with the invention, it is an advantage to combine a local periodic displacement of the beam in the vicinity of a mean point with a continuous displacement of the mean point on the test piece. It is thus possi~le in particular to combine a longitudinal movement of translation at constant speed with a transverse reciprocating movement of translation or with a continuous movement of rotation which _3_ ~`- - '- :'-. - .......... . .
- - :
, is centered on the mean point such as a movement of conical revolution of a beam havin~ an oblique angle of incidence.
These movements are preferably carr.ied out at constant speed.
In conjunction with the longiludinal displacement of the beam~ it is an advantage to have recourse to a particular mode of visual display of the energies of the back-scattered waves whereby the energies which exceed a predetermined threshold value are visualized on a screen as a function of the longitudinal displacement. It is possible in particular to employ the screen of a storage cathode-ray tube and to control the spot deflection plates respectively by means of a volta~e which is proportional to the longitudinal displacement of the incident beam and by means of the time base of the incident waves by modulating the intensity of the spot by means of the energy of the detected back-scattered waves.
However, the invention does not exclude the use of other modes of visualization entailing the need for observa-tion in stages along the surface of the test piece. In particular, the variations in energy of the back-scattered waves during a local periodic displacement of the incident beam can be recorded on a single visual display screen, for example by photographing the screen of a cathode-ray tube.
In this case, said displacement is preferably obtained by means of a conical movement of revolution of the beam at constant speed.
The invention is also concerned with a device for : nondestructive testing of materials in which said device essentially comprises means for emitting an incident beam of ultrasonic wave trains, means for orienting sa.id beam at an oblique angle of incidence with respect to the surfac2 of a .
' - ~ . '' ~ ' "' ' "
~ - '- ' ~ ', ' .
~L~7~
test piece, means for detec-ting waves wh:Lch are back-scattered by said test piece and preferably a-t the same angle, sa.id detection means being provided if necessary with the same transducer as the emission means, and means for dis~
placing the beam with respect to -the -test piece and maintain-ing constant the angle of incidence and the len~th of the acoustic path between the emission means and the sur~ace of said test piece.
: Preferably, an emi.tting and/or receiving ultrasonic transducer is mounted within a leak-tight apparatus closed by a window in contact with the test piece and Eilled with an acoustic couplant liquid such as water at least over the enti.re acoustic path between the transducer and the window.
The apparatus advantageously contains not only the .
transducer but also beam-orienting means constituted especially by at least one reflecting mirror and/or means for local dis-placement of the beam especially by tran~lational or rotational -:
motion of the reflecting mirror and/or the transducer.
In one of the preferred embodiments of the device, the transducer is mounted within a slide tube which is capable of translational motion within the apparatus in a direction parallel to the window. The beam is emitted in an oblique direction through the window by the transducer which is oriented in this direction or by an acoustic mirror : 25 which i5 also mounted on the slide tube if the transducer cannot be oriented in this direction. The slide tube can be displaced in a reciprocating movement of translation either by hand or preferably by means of an electric motor and a cam against which the extremity of the slide tube is maintained applied by means of a spring.
In another preferred embodiment of the cLevice, the - , . .
.. .
-, ~7V~
apparatus comprises a movable -transducer mounted on a movable member designed to carry out a conical movement of revolution of the beam produced by the -transducer which is oriented at an oblique angle towards a point of the surface of the test piece through -the window of the apparatus, or a stationary transducer having an axis at right angles to the test piece and a rotating system of reflecting mirrors for carrying out the conical movement of revolu-tion of the beam at an oblique angle towards a point of the surface of the test piece through the window of the apparatus.
A more complete understanding of the invention will be gained from the following description and from a study of the accompanying drawings in which a few Pmbodiments of the method and the device according to the present invention are illustrated solely by way of example, and in which :
- Fig. 1 shows diagrammatically a first alternative emhodiment of a device in accordance with the invention ;
- Fi~. 2 shows diagrammatically a second alternative embodiment of the device ;
~ Fig. 3 shows a mode of displacement and a type of visual display obtained by means of the alternative embodiment of Fig. 1 ;
- Fig. 4A shows a mode of displacement and a type of visual aisplay obtained hy means of the alternative embodiment of ~ig. 2 ;
Fig~ ~B ~hows a mode of composite displacement obtained b~ means o~ t~e alternative embodiment of ~ig. 2 and a corresponding type of visual display , - Fig. 5 is a longitudinal sectional view showing an apparatus according to the invention in which the beam is displaced in translational motion ;
.
.~ . . - - . -" - ' ' ' ~ ' ' "' , . .
~7~
- Fig. 6 is a transverse sec-tional view showing the apparatus of Fig. 5 ;
- Fig. 7 is a diagrammatic view showing an assembly which is employed for adjusting the apparatus ;
- Fig. 8 is a partial longitudinal sectional view showing an apparatus according to the invention in which the beam is displaced in rotational motion ;
- Fig. 9 is a longitudinal sectional view showing an apparatus according to the invention with translational displacement and an integrated displacement pickup ;
- Fig. 10 is a longitudinal sectional view showing another apparatus in accordance with the invention comprising an integrated displacement pickup in the case of displacement in rotational motion.
In its application to the measurement of hardness penetration of steel parts, the method according to the invention is based on the observation of ul-trasonic waves scattered by the part and more precisely on the observation of variations in energy of the ultrasonic waves which are scattered backwards by the grains of the material after attenuation by these latter within the thickness of the part.
In fact, it is already known that in the case of a given part corresponding to a predetermined mean volume of initial austenite grains of the steel (prior to heat treatment), scattering of the ultrasonic waves is much w~aker in a martensitic structure as obtained by rapid cooling of steel than in a pearlitic structure as obtained by slow cooling.
The degree of scattering is of intermediate value in the case of stru~tures obtained with an intermediate cool:ing rate~
~owevex, the difference in scattering is usually sufficiently well defined between the hardened steel layer and the - -~ -.
unhardened portion to permit determination of the depth oE
the hardene~ layer, especially in the case of substantial hardness penetrations obtained or example by high-frequency treatment.
The me-thod according to the invention makes it possible to observe this difference by making use of particularly convenient means for establishing a mean value of back-scattered energies over a predetermined fraction of surface of the test piece and to measure directly in a receiver for the visuali~ation of said energies the distance between the surface of the test piece and the depth limit of the hardened layer.
In the practical application of the invention, preference is given to the use of a single transducer or ultrasonic probe for emitting ultrasonic wave trains constit-uting the incident beam which is directed onto the test piece and for detecting the ultrasonic waves back-scattered by the piece, or echos. However, in other forms of applica-tion, the emission and detection can be carried out by means of different probes. ~ ~
The different examples of device which will be -described hereinafter all entail the use of a single probe.
Moreover, said probe is inclined or combined with suitable -.
devices so as to direct the beam of ultrasonic waves at an ~5 oblique angle of incidence onto the test piece and this angle of incidence remains constant during a ~isplacement to which the beam is subjected with respect to the surface of the test plece while also maintaining constant the length of the ; acoustic path between the probe and the test pieceO
By virtue of the means which will be described later, the beam is subjected to a local periodic displacement at a . . - , .
.. .
~7~
uniform speed which can b~ ei-ther a reciproca-tin~ movem~nt of translation or a continuous movement of rotation. This local displacement is combined in some cases with a disp]ace-ment of the mean point of the local displacement, which can be either non-con-tinuous or continuous at a constant, low speed with respect -to the local displacement.
The inclination of the angle of incidence of the beam offers a number of advantages. In the first place, the high-amplitude echo produced by reflection from the surface of the test piece can thus be removed from the detection. Said inclination also makes it possible in the case of an an~le of incidence which is greater than the an~le of incidence corresponding to the critical reflection of the longitudinal waves to ensure that the transverse waves which have the advantage of much lower velocity than longitudinal waves are alone refracted within the test piece. Moreover, the fact that the refracted beam is inclined increases the length of the wave path within the thickness of the part being tested.
The devices which are shown diagrammatically in the general views of Figs. 1 and 2 differ from each other in the mode of visualization of the energies of the back-scattered waves.
The device of Fig. 1 essentially comprises a wave-train generator 1 which controls the emission of the probe 7.
Said probe produces a beam to which is imparted a periodic local movement a~ove a test-piece holder 9 by mechanical means which will be described hereinafter. In the ca~e of treatment of si~nals corresponding to the back-scattered waves detected by the probe 7~ the device comprises in series an amplifier 2, a filter 3 and a detection unit 4 A visual display of the si~nals is produced on the screen of a cathode-ray tube 5. The _g _ , .
amplitude of the echos detected con-trols the vertical deflection plates of the cathode-ray tuhe whilst a tirne base 6 controls the horizontal deflection plates. It is thus possible to obtain aEter adjustment of the time base in synchronism with the emission of the incident beam a repre-sentation of the variations in energy E of the echos as a function of the distance D travelled by the ultrasonic waves within the material.
In the case in which a part of hardened steel is thus subjected to testing, the image is of the type shown in Fig. 3. The device is advantageously provided in addition with a camera which serves to record the energy curves visualized on the screen of the cathode-ray tube throughout the duration of the local displacement of the probe and thus to display the mean curve of the energ~ scattered over a ; narrow integration range which is dependent on the amplitude of displacement of the probe. The thickness of the hardened steel layer cor~esponds to the distance between the first two .
echos of high amplitude ~H in ~ig. 3).
The device of Fig. 1 has a disadvantage in that it ..
provides the information in deferred time since it entails the superimposition of a plurality of successive images without permitting a geographlcal representation, the observed result being a mean value between a number o~ points of the test ~5 piece.
The device shown in Fig. 2 circumvents these dis-advantages and makes it possible in particular to establish in real time a geoyraphical representation of the thickness o~ the hardened layer o~ a steel part. As in the previous case, this device comprises an ultrasonic wave-train generator 1, the probe 7 which is capable of moving in a direction ~ -' " '. . ; ,.,~ : ' ' ~
~o~
parallel to a test-piece holder 9, an amplifier 2, a fil~er 3, a detection unit ~, a cathocle-ray tube 5 and a -time base G.
'~he device differs from the previous embodiment in that the local displacement of -the probe or even the complete dis-placement of the apparatus if necessary is measured at eachinstant by means of an electrical device 8 which can be a linear or rotational displacement pickup.
The voltage delivered by the device is proportional to the displacement of the probe and controls the horizontal deflection plates of the cathode-ray tube 5. The time base 6 controls the vertical de~lection plates in synchronism with the emission of the incident beam whilst the detected signals whose amplitude is characteristic of the back-scattered energy are employed for modulating the light intensity of the spot of the cathode-ray tube. There is thus obtained direGtly on the screen of the cathode-ray tube a yeographical representa-tion o~ the origln of the echos within the thickness of the test piece as a function of the measured displacement of the probe as shown in Figs. 4A and 4B which show the variations in depth H of the hardened layer.
There will now be described in a number of different embodiments the constr~ction of the mechanical portion o~
the device according to the invention at the level of the ultrasonic probe and means for displacing the beam.
In these different alternative embodiments, a single txansducer carries out the emission of the incident beam of ultrasonic wave trains and the reception of the waves which are back-scattered by the test piece. Said transducer is mounted with means for orienting and displacing the beam within the interior of a leak-tight apparatus filled ~ith a liquid which provides acoustic couplill~ between ~ '~ . - -,, ~ - -- .
-. ~ ~ ' - 11 , :
- .
.. ..
, the transducer and the test piece and consists ~spec:ially oE
water.
In each case, said leak-tight apparatus is closed by a window which permits transmission of the ultrasonic S waves between the transducer or ultrasonic probe and the surface of the test piece, the liquid beinc~ retained by a thin flexible diaphragm which is transparent to ultrasonic waves and placed over the window. Supporting and/or fixing members serve to place the apparatus in position with the flexible diaphragm applied in contact with the surface of the test piece.
The ultrasonic beam can be directed obliquely towards the window in order to obtain an oblique angle of incidence which can be adjusted if necessary either by inclinin~ the probe itself or by making use of systems for reflecting the beam.
Local displacement of the beam can be obtained by imparting a suitable movement to the probe or to reflecting systems within the apparatus ; this can be carried out either by hand or by means of a motor. This local displacement can consist especially of a periodic movement of translation or of rotation, thus making it possible to adopt either a mode of visualization in accordance with Fig. 3 or a mode of visualization in accordance with Fig. 4A as requirements dictate. In addition, however, the apparatus itself can be j displaced if necessary over the surface of the test piece in order to carry out a composite mode of displacement of the beam, thus permitting a mode of visualization i~ accordance with Fi~. 4B~
The apparatus shown in Figs. 5 and 6 permits rectilinear displacement o the probe and of a re:Electin~
- .. '-., ' - `- ' - . , - ' ,, . ' 7~7 mirror which ensures orierltation of -the beam. The ~pparatus may be employed exactly as shown in the arrangement of Fig. 1 with a mode of rectilinear translational displacemen-t and a mode of visualization in accordance with Fig. 3. The apparatus can also comprise an additional external displac~ment pickup (of the wire type, for example) and can be employed in the arrangement of Fig. 2 with a composi-te mode of displacemen-t consisting of two perpendicular movements of translation and a mode of visualization in accordance with Fig. 4B.
The probe 40 and the mirror 43 are mounted within a hollow cylindrical slide tube 42 which is in turn mounted so as to be capable of translational motion in the axis of the ; cylindrical shell 41 of the apparatus. This latter also contains a reduction-gear motor 23, the output shaft of which is mounted in the axis of the slide tube and carries a cam 49 against which is applied the extremity of the slide tube 42 by means of an antifriction bearing 24. The probe 40 is locked ; within the slide tube 42 by means of a piIl 48 which is screwed in position at the end of this latter ; said pin serves to support the bearing 24. The reflecting mirror 43 is p]aced opposite to the probe within the slide tube and fastened by means of a transverse locking-pin 37 which permits removal and replacement of said mirror. A third member 12 is screwed into the end of the slide tube. Said member has a blind-end bore for accommodating a spring 38 which is applied against the end-wal] 13 of the apparatus and thus urges the moving system against the cam 49. The end portion of the shell 41 is closed by a member 46 which is fixed in position by means of screws 34 and also has the design function of maintaining the spring-supporting end-wall 13.
Fine guiding of the slide tube is carried out by ;
- ..
~ -13-. -.
7~
means of bronze bearing-bushes 17 which are rigidly Eixed to the shell 41 and by means of anti~riction bearings 27 which not only serve to guide the moving system but also to prevent rotation of this latter about its axis. Said bearings are accordingly supported within a longitud:inal groove 21 formed within the bore of the shell 41. The cross-pins 22 which support the bearings 27 are displaced off-center and the positioning of these latter serves to adjust the clearance between the moving system and the shell. Screws 37 serve to lock the cross-pins 22 in position.
The apparatus is designed to be ~illed in the central portion thereof with a liquid which ensures acoustic coupling between the probe and the surface of the test piece.
; Leak-tightness of the chamber which contains the liquid is achieved :
- opposite to the openlng of the shell by means of a thin flexible diaphragm ll which is transparent to ultrasonic waves, said diaphragm being held in position by means of a retaining ring 45 which is clamped against a recessed diaphragm support 44 which limits the window ;
- between the shell and the slide tube by means of lipped seals 25 ;
- between the probe and the slide tube and between the bearing member of the spring 38 and the slide tube by means of 0-ring seals 26 fitted within grooves which are machined in the slide tube.
Filling o~ the chamber is carried out through an opening formed in the shell which is closed by means of a threaded plug 33 fitted with a seal 32. The chamber can be put under pressure by screwing the member 12 into the slide tube, this being accomplished by employing the key 14 which is ;--.. ;-,- ~ - ., ' , placed across -the slots Eormed in the end--wall 13.
The slide tube is pierced by an opening at the level of the probe through which are passed the leads for supplying current to this latter. The leads are soldered to a socket-outlet connector which is fixed on the external wall of theshell. There is placed at the end of the shell ~1 a right-angled member 47, one portion of which is cut out on one side so as to form a fork which serves as a support for fixing the apparatus on the parts to be tested. Said member ~7 is fixed in position by passing a screw 39 through a slot which permits of height adjustment.
The mirror 43 may be dispensed with if necessary if, in an alternative form of the preceding embodiment, the probe 40 is modified so as to ensure that the sensitive piezoelectric element is inclined at a sharp angle to the axis of the slide tube and placed opposite to the window of the apparatus.
Moreover, the mirror 43 can be replaced by a system 30 of complementary mirrors which is illustrated in Fig. 7.
This system serves to adjust the orientation of the plane of incidence of waves at right angles with respect to the surface of the test piece or with respect to the surface which is tangent to the surface of the test piece 31. The complementary mirrors are oriented so as -to return a fraction o~ the energy reflected from the surface of the test piece to the emitting~
receiving probe 40. The adjustment is carried out by determin-ing the orientation in which the reflected enexgy received by the probe is of maximum value. Since the distance travelled by the reflected waves is greater than the distance travelled 30 by the scattered waves, the respective echos are per ectly separated when they are received on the viewing screen.
- ~ -- - - -.......
- : -~1~37~
In the apparat7~s of Fig. 8, a local displacement ofthe incident beam of ultrasonic waves is carried out by means of a conical movement of revolution oE the beam.
Said apparatus can be employed in par-ticular exactly as shown in the arranyement of Fig. 1 with a mode of displacement in rotation and a mode of visualization in accordance with Fig. 3. The apparatus can also be associated with an additional ex-ternal displacement pickup (oE the wire type, for example) in order to be employed in the arrangement of Fi~. 2 with a composite mode of displacement of the beam, ; in local rotational motion and in translational motion, in conjunction with a mode of visualization in accordance with Fig. 4B.
The probe 50 is placed in the axis of a leak-tight ; 15 cylindrical shell 51 which terminates in a frusto-conical portion 53 (the bottom portion shown in Fig. 8) comprising a window which is perpendicular to the axis.
A rotating system comprising two mirrors for reflecting the beam emitted by the probe is mounted in front of this latter. A first mirror which is oriented at 45 degrees to the axis of the probe reflects the beam radially ; then a second mirror reflects said beam at an oblique angle with respect to the axis towards the window of the apparatus. These two mirrors are machined respectively in two steel members 57 and 56, these latter being assembled so as to form a circular component which is mounted in a bored cylindrical support 520 The support 52 is fixed on the rotor of a motor ~`
65 having a hollow shaEt, the probe 50 being located in the axis of sald motor. This moving system is centered in the cylindrical shell 51 by means of an antifriction bearing 66 which ensures the necPssary mobility without play.
~g7(~
The apparatus is deslgned to be filled with a liquid which ensures acoustic coupling between -the probe and the test piece ; leak-tightness is ensured :
- at the level of the window by a thin flexible diaphragm 55 which is transparent to ultrasonic waves and held in posi-tion by a clamp 54 ;
- between the probe and the shell by an 0-ring seal 64 which is compressed by means of a nut 58.
Pressurization of the liquid in order to cause deformation of the diaphragm is carried out by downward displacement of the probe within the apparatus, locking being obtained by tightening the nut 58.
The apparatus shown in Fig. 9 permits rectilinear translational displacement of the emitting-receiving probe.
This apparatus differs from that shown in Figs. 5 and 6 in the fact that it comprises a device for measuring the dis-placement of the integrated probe. Said apparatus is advan~-ageously employed exactly as shown in the arranyement of Fig. 2 with `a mode of translational displacement and a mode of visualization in accordance with Fig. 4A.
The probe 67 which is designed so as to ensure that the sensitive piezoelectric element is steeply inclined to the axis of the apparatus so as to emit the acoustic waves at an oblique angle is mounted within the interior of a hollow cylindrical slide tube 68 which is capable of moving within a cylindrical shell 69. The slide tube 68 is actuated manually by means of a member 70 on which it is engaged and maintained by means of a locking-pin 71. A hollow cross-pin 72 fixed in the shell 69 passes through a double slot formed in the op~rating member 70 and thus makes it possible to prevent the assembly of members 67, 68 and 70 from rotating about the axis . -. -: . .. :
.
~1~)7q~ 37 of the apparatus.
The displacement o -the men~ers 67, 68 and 70 in linear translational motion is measured by means of a displace-ment pickup 73 which is keyed i.n the mell~er 70 by means of an end-cap 74. The movable pin of the displacement plckup is : rigidly fixed to the shell of the apparatus which serves as a reference in the positioning of the members 67, 68 and 70 : by virtue of a locking-pin 75.
An opening formed in the slide tube 68 and the shell 69 provides a passageway for the acoustic beam produced by the probe ; the orientation of this latter is fixed by means of a pin 76.
The apparatus is designed to be filled in the central portion thereof with a liquid whi.ch ensures acoustic ` 15 coupling between the probe and the surface of the test piece. ~ .
; Leak-tightness of the chamber which contains the liquid is . ensured :
- opposite to the opening of the shell and of the slide tube by a thin flexible diaphragm 77 which is transparent to ultrasonic waves and held in position by a retaining ring 78 which is clamped against a recessed diaphragm support limited by the window ;
- between the shell and the slide tube and between the probe : and the slide tube by means of 0-ring seals 790 2S Filling of the chamber is carried out from the slide tube extremity which is closed by means of a threaded plug 80 ;
the greater or lesser engagement of this latter makes it . possible to adjust the pressure within thP.chamber and con-sequently the deformation of the flexible diaphragm 77.
El2ctrica1 connection o the probe is ensured by a connector : 81 from which leads 82 extend to a socket-outlet 83 which is 18- .
. . ... .
.. - -, - ' , - ' ' -. :
also provided with -terminals joined to the leads Erom the displacement pickup.
Provision is made Eor bearing members 8~ which permit suitable positioning of the apparatus on the surface of the part to be tested.
In the apparatus of Fig. lOr a local displacement of the incident beam of ultrasonic waves is carriecl out by means of a conical movement of revolution of the beam. This apparatus differs from that shown in Fig. 8 essentially in the fact that it comprises a device for measurin~ the displace-ment o~ the integrated probe. Said apparatus is advantageously employed exactly as shown in the arrangement of Fig. 2 with a mode of displacement in rotational motion and a mode of visualization in accordance with Fig. 4A.
The probe 85 is maintained by means of screws 87 in an oblique position within an eccentric hole formed in a probe-holder 86 consisting of a cylindrical member o~ revolu-tion. The probe-holder is mounted within a hollow shell constituted by two sections 88 and 89 which are assembled together by means o~ screws 90. A ball-bearing 91 serves to support the probe-holder an~ this latter can accordingly be subjected within the apparatus to a movement of rotation about its axis. In consequence, a conical movement of revolution about the axis o~ the apparatus can be imparted to the 2~ acoustic beam produced by the probe.
The movement of the probe 85 and of the probe-holder 86 is controlled by a knurled ~nob 92 located outside ~he shell and secured by means of a screw 93 to the shaft o~
a potentiometer 9~ which is ~i~ed on the cover of -the apparatus.
The apparatus is designed to be partly filled wi-th a - " ' ' ' ' "
-19- ~ ~
, - .
. ~ . . - . : . : :
liquid whi.ch provides acoustic coupling between the probe and the test piece ; leak-tightness is ensu:red :
- at the level of the window by a thin diaphragm 96 which is transparent to ultrasonic waves and held in position by a retaining ring 97 and an 0-ring seal 98 ;
- at the level of the assembly of the two sections 88 and 89 which constitute the shell of the apparatus by means of a seal 99 ;
~ at the level of the axis of the probe-holder ~6 and of the top portion of the shell 89 by means of a lipped seal lO0. ..
In order to produce the deformation of the diaphragm, the liquid is put under pressure by means of a piston constit-uted by an assembly of components and seals 101 to 106, the position of which is defined by rotating the member 104. -The probe 85 and the potentiometer 94 are connected electrically, respectively to socket-outlets 107 and 108 which are fixed on the shell of the apparatus.
Within the field of application to the measurement of hardness penetration in steel parts/ the apparatuses described are utilized to advantage by adopting ultrasonic-wave frequencies within the range of 5 to 20 Mc/s with wave-train repetition fre~uencies of 2 kc/s, for example. In order to permit direct reading of the hardness penetration, calibra tion of the visual display and more precisely of the time base ~5 of the cathode-ray tu~e can be carried out by seekin~ to obtain multiple echos of longitudinal waves in a Shim of known thickne~s. If the measurements are then performed with : different angles of incidence of the beam,. it is only . ~.
n~cessary to apply a corrective coefficient to the result determined in accordance with the preliminary calibration.
: By way of example, this coefficient is respectively 0.~ ;
' ~ , ' ' ' ' . -.20-. . .
,:
0.35 ; 0.3 in the case of angles of incidence of 18.5 ; 21 ;
or 23 degrees when the couplant liquid is water.
It is readily apparent that the invention is not limited in any sense to the embodiments which have been described in the foregoin~ with reference to the accompanying drawings. Depending on the applications which are contem-plated, consideration can be given to many possible alter-native forms which are accessible to any one versed in the art witho~lt thereby departing either from the scope or the spirit of the invention.
.
. - :
Claims (19)
1. A method for non-destructive testing of materials comprising directing an incident beam of ultrasonic waves onto a test piece at a constant angle of incidence, detecting the waves back-scattered at the same angle, subjecting said incident beam to a composite movement comprising a local displacement in the vicinity of a mean point combined with a longitudinal displace-ment of said mean point and forming a display of the successive back-scattered waves detected on a cathode ray tube by modulating the intensity of the spot of the cathode ray tube by the energy of said waves, and controlling the spot deflection plates respec-tively by a voltage proportional to only said longitudinal displa-cement of the incident waves and by a time base of the incident waves.
2. A method according to claim 1, wherein said test piece is a hardened steel piece and whereby the variation of the depth of the hardened layer along said longitudinal displacement is displayed.
3. A method as defined in claim 2, wherein the beam is directed onto the test piece at a constant oblique angle of inci-dence and the back-scattered waves are detected at the same angle of incidence.
4. A method as defined in claim 2, wherein said local displacement is carried out at constant speed in the vicinity of a mean point and is a reciprocating movement of transverse trans-lation or a continuous movement of rotation centered on said mean point.
5. A method as defined in claim 4, wherein said local displacement is a conical movement of revolution of the beam.
6. A method as defined in claim 4, wherein the varia-tions in energy of the back-scattered waves detected in the case of different successive wave trains of the incident beam are recorded on a single visual display screen during the local dis-placement aforesaid.
7. A method as defined in claim 1, wherein said longi-tudinal displacement of the beam is a continuous motion at cons-tant speed in a longitudinal direction parallel to the surface of the test piece and in a plane which contains the beam.
8. A method as defined in claim 1, wherein the waves detected are displayed only when their energies are higher than a predetermined threshold.
9. A device for non-destructive testing of materials, wherein said device comprises means for emitting an incident beam of ultrasonic wave trains, means for orienting said beam at an oblique angle of incidence with respect to the surface of a test piece, means for detecting waves which are back-scattered by said test piece at the same angle, means for displacing the beam with respect to the test piece while maintaining constant the angle of incidence and the length of the acoustic path between the emission means and the surface of said test piece, said displacing means imparting to the beam a longitudinal displacement of a mean point and a local displacement in the vicinity of said mean point, and means for forming a display of the successive back-scattered waves detected on a cathode ray tube by modulating the intensity of the spot of the cathode ray tube by the energy of said waves, and controlling the spot deflection plates respectively by a vol-tage proportional to only said longitudinal displacement of the incident waves and by a time base of the incident waves.
10. A device according to claim 9, wherein said local displacement is carried out at constant speed in the vicinity of a mean point and is a reciprocating movement of transverse trans-lation or a continuous movement of rotation centered on said mean point.
11. A device as defined in claim 10, wherein said device comprises a transducer for emitting and/or receiving ultrasonic waves mounted within a leak-tight apparatus which is closed by a window in contact with the test piece and is filled with an acous-tic couplant liquid such as water at least along the entire acoustic path between the transducer and the window.
12. A device as defined in claim 11, wherein said win-dow is constituted by a flexible diaphragm.
13. A device as defined in claim 11, wherein the trans-ducer is mounted within a slide tube which is capable of transla-tional motion within the apparatus in a direction parallel to the window and wherein said device comprises means for displacing said slide tube in a reciprocating movement of translation.
14. A device as defined in claim 13, wherein said device comprises within the interior of the leak-tight apparatus an electric motor for driving a cam and means for maintaining the slide tube in contact with said cam.
15. A device as defined in claim 13, wherein said device comprises a pickup for measuring the displacement of the slide tube.
16. A device as defined in claim 13, wherein said device comprises a mirror for reflecting the beam in an oblique direction through the window, said mirror being mounted within said slide tube.
17. A device as defined in claim 13, wherein said device comprises in addition at least one reflecting surface for returning to the transducer a fraction of the waves reflected from the test piece.
18. A device as defined in claim 9, wherein said device comprises a rotating system of mirrors for reflecting the beam and subjecting said beam to a conical movement of revolution having an axis at right angles to the test piece.
19. A device as defined in claim 18, wherein said sys-tem is rotatably mounted with respect to the axis of the trans-ducer and comprises a first mirror for reflecting the beam in a radial direction and a second mirror for reflecting the beam from said first mirror at an oblique angle through a window located at right angles to said axis.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR7500809A FR2297419A1 (en) | 1975-01-13 | 1975-01-13 | METHOD AND DEVICE FOR NON-DESTRUCTIVE EXAMINATION OF MATERIALS BY ULTRASONICS |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1070007A true CA1070007A (en) | 1980-01-15 |
Family
ID=9149667
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA243,596A Expired CA1070007A (en) | 1975-01-13 | 1976-01-12 | Method and device for the nondestructive testing of materials by means of ultrasonic waves |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS5199092A (en) |
| CA (1) | CA1070007A (en) |
| DE (1) | DE2600720A1 (en) |
| FR (1) | FR2297419A1 (en) |
| GB (1) | GB1535831A (en) |
| IT (1) | IT1054777B (en) |
| SE (1) | SE7600159L (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS541077A (en) * | 1977-06-03 | 1979-01-06 | Hitachi Ltd | B scope image distortion reducing apparatus |
| JPS54158986A (en) * | 1978-06-06 | 1979-12-15 | Canon Holosonics | Ultrasonic imaging device |
| DE2926173A1 (en) * | 1979-06-28 | 1981-01-15 | Siemens Ag | METHOD FOR DESTRUCTION-FREE MATERIAL TESTING WITH ULTRASONIC IMPULSES |
| JPH0233169Y2 (en) * | 1980-12-24 | 1990-09-06 | ||
| FR2530342A1 (en) * | 1982-07-13 | 1984-01-20 | Cogema | METHOD AND DEVICE FOR ULTRASONIC ECHOGRAPHY |
| US10302600B2 (en) | 2016-01-19 | 2019-05-28 | Northrop Grumman Innovation Systems, Inc. | Inspection devices and related systems and methods |
| DE102020211379A1 (en) | 2020-09-10 | 2022-03-10 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung eingetragener Verein | Process for the non-destructive determination of the hardening depth on surface-hardened components |
| CN114894900B (en) * | 2022-07-12 | 2022-09-13 | 泉州装备制造研究所 | Method for measuring depth of alloy hardening layer by ultrasonic nondestructive measurement |
-
1975
- 1975-01-13 FR FR7500809A patent/FR2297419A1/en active Granted
-
1976
- 1976-01-07 GB GB408/76A patent/GB1535831A/en not_active Expired
- 1976-01-09 DE DE19762600720 patent/DE2600720A1/en active Pending
- 1976-01-09 SE SE7600159A patent/SE7600159L/en unknown
- 1976-01-12 CA CA243,596A patent/CA1070007A/en not_active Expired
- 1976-01-12 IT IT19172/76A patent/IT1054777B/en active
- 1976-01-13 JP JP51004572A patent/JPS5199092A/ja active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| GB1535831A (en) | 1978-12-13 |
| JPS5199092A (en) | 1976-09-01 |
| SE7600159L (en) | 1976-07-14 |
| IT1054777B (en) | 1981-11-30 |
| FR2297419B1 (en) | 1978-02-03 |
| FR2297419A1 (en) | 1976-08-06 |
| DE2600720A1 (en) | 1976-07-15 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4213344A (en) | Method and apparatus for providing dynamic focussing and beam steering in an ultrasonic apparatus | |
| US7021143B2 (en) | Cylindrically-rotating ultrasonic phased array inspection method for resistance spot welds | |
| US4807476A (en) | Variable angle transducer system and apparatus for pulse echo inspection of laminated parts through a full radial arc | |
| US8368289B2 (en) | Nondestructive testing apparatus and method | |
| US10761066B2 (en) | Micro-resolution ultrasonic nondestructive imaging method | |
| US8997574B2 (en) | Oblique flaw detection using ultrasonic transducers | |
| US3384733A (en) | Ultrasonic inspection system and apparatus for resistance welds and the like | |
| JPS63243751A (en) | Method, jig and apparatus for ultrasonic flaw detection of rotary body for bearing | |
| US9797867B2 (en) | Apparatus and method for inspecting a laminated structure | |
| US4484475A (en) | Method of measuring contact stress at contacting surfaces of abutting solid masses | |
| US8161818B2 (en) | Device for detecting a flaw in a component | |
| EP0559762A1 (en) | Ultrasonic method and apparatus for measuring outside diameter of tube | |
| CA1070007A (en) | Method and device for the nondestructive testing of materials by means of ultrasonic waves | |
| NO303656B1 (en) | Method and apparatus for measuring the distribution of concentrations of constituents in a medium | |
| US3178933A (en) | Method and apparatus for ultrasonic weld inspection and display | |
| US6588278B1 (en) | Ultrasonic inspection device and ultrasonic probe | |
| US5503019A (en) | Method and apparatus for ultrasonically inspecting the surface of the bore of a railroad wheel axle | |
| US5203869A (en) | Ultrasonic flange radii inspection transducer device | |
| US4991441A (en) | Positioning assembly for a transducer in a boresonic inspection system | |
| FR2530342A1 (en) | METHOD AND DEVICE FOR ULTRASONIC ECHOGRAPHY | |
| EP0219519B1 (en) | Non-destructive method for determining at least one point of a cracking front in a part and device for implementing such method | |
| DE112009000944T5 (en) | System and method for testing welds | |
| US3596504A (en) | Ultrasonic search unit | |
| US3546927A (en) | Ultrasonic testing apparatus | |
| Knollman et al. | Real‐time ultrasonic imaging methodology in nondestructive testing |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |