WO1986004991A1 - Classification de l'acier - Google Patents

Classification de l'acier Download PDF

Info

Publication number
WO1986004991A1
WO1986004991A1 PCT/AU1986/000039 AU8600039W WO8604991A1 WO 1986004991 A1 WO1986004991 A1 WO 1986004991A1 AU 8600039 W AU8600039 W AU 8600039W WO 8604991 A1 WO8604991 A1 WO 8604991A1
Authority
WO
WIPO (PCT)
Prior art keywords
specimen
variable
name
coeff
row
Prior art date
Application number
PCT/AU1986/000039
Other languages
English (en)
Inventor
Kenneth Garry Kemlo
Original Assignee
The Broken Hill Proprietary Company Limited
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by The Broken Hill Proprietary Company Limited filed Critical The Broken Hill Proprietary Company Limited
Priority to DE8686901303T priority Critical patent/DE3674675D1/de
Publication of WO1986004991A1 publication Critical patent/WO1986004991A1/fr
Priority to KR860700716A priority patent/KR880700265A/ko

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/72—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/20—Metals
    • G01N33/202—Constituents thereof
    • G01N33/2022—Non-metallic constituents

Definitions

  • This invention relates to methods and apparatus for identifying and classifying steels.
  • One current method known as the "Forster” method, relieson a comparison between the magnetic properties of a steel specimen to be tested and a "standard" sample which has been chemically analysed.
  • the test specimen and the standard sample are inserted into separate coils, each having primary and secondary windings.
  • the primary windings of the two coils are subjected to a common energizing current of fixed frequency and a comparison is made between output signals induced in the secondary windings of the two coils.
  • the output signals may be applied to a comparison circuit which generates a display on a screen.
  • the Forster method of steel classification has several limitations and problems in practice. These include: 1. A highly trained operator is required to interpret the trace or screen display to enable satisfactory information to be gained.
  • the method is very sensitive to variations in temperature between the test specimen and the standard sample.
  • Results depend on chemical analysis of the initial standard sample. Once it is considered that a change in grade has occurred the new grade cannot be determined without further recourse to sampling and subsequent chemical analysis.
  • the present invention has arisen from work aimed at developing an improved magnetic testing method which will enable a more accurate and convenient testing procedure.
  • the invention provides a method of classifying a steel specimen comprising: presenting the specimen to a coil means having a primary winding and a secondary winding such that the specimen contributes to an inductive coupling between the primary winding and the secondary winding; applying an excitation current to the primary winding at each of a plurality of excitation frequencies whereby to induce in the secondary winding for each excitation frequency a signal indicative of an induction value of the specimen; and determining a grade classification of the specimen dependent on the induction values obtained at said excitation frequencies.
  • the primary and secondary windings of the coil means may be generally co-axial and spaced apart in the axial direction and the specimen may be positioned so as to extend into both windings.
  • the primary and secondary windings may be disposed about a coupling member defining a coupling gap and the specimen may be position so as to provide an inductive coupling across said gap.
  • the critical frequencies at which signals induced in the secondary winding are exactly out of phase with the excitation current are also determined and the determination of the grade classification is also determined.
  • the grade classification is determined according to the value of a discriminant function of the form a ⁇ +b ⁇ +c ⁇ +. « where ⁇ , ⁇ , ⁇ ........ are attributes of the specimen comprising said induction values and a,b,c. « are coefficients reflecting the degree to which the respective attributes are effective to discriminate between steel grades.
  • ⁇ , ⁇ , ⁇ ........ are attributes of the specimen comprising said induction values
  • a,b,c. « are coefficients reflecting the degree to which the respective attributes are effective to discriminate between steel grades.
  • said attributes also comprise said critical frequencies.
  • the invention also provides apparatus for c'lassifying steel specimens, comprising: coil means having a primary winding and a secondary winding to be inductively coupled via a steel specimen to be classified; excitation means for applying an excitation current to the primary winding at each of a plurality of excitation frequencies whereby to induce in the secondary winding for each frequency an output signal indicative of an induction value of the specimen; and signal processing means to receive the output signals indicative of the induction values at said frequencies and to determine a grade classification of the specimen dependent on those values.
  • Figure 1 is a circuit diagram of conventionalequipment operating on the "Forster" method
  • Figures 2, 3 and 4 illustrate equipment operable in accordance with the present invention
  • Figure 5 is a canonical variable plot for various steel grades
  • Figure 6 is a diagram showing the skin effect for steel specimens at varying excitation frequencies;
  • Figure 7 illustrates the relationship between the indudtion and cross-sectional area of the specimens;
  • Figure 8 illustrates the relationship between the induction and the measured surface area of the specimens;
  • Figure 9 is a plot of the shape factor of various specimens against a brea ⁇ Vth/thickness ratio.
  • Figure 10 is a graph showing a correlation between the decarburisation depth and measured inductions at various frequencies.
  • FIG. 1 Mode for carrying out the Invention Apparatus conventionally used for classifying specimens by the "Forster" method is shown in Figure 1.
  • Two independent coils 1, 2 are used and comparisons are made between a chemically analysed sample 3 inserted into coil 1 and the test sample 4 inserted into coil 2.
  • the primary windings of the coils are connected to a 50 hz signal source 6 so that the same current (I) flows through the primaries (P) of both coils and a comparison is made between the two secondaries (S).
  • FIG. 2 and 3 One apparatus for testing in accordance with /the present invention is illustrated in Figures 2 and 3.
  • this apparatus two coils 7, 8 are strapped together with their axes aligned, to enable a steel specimen 9 to be inserted through both coils.
  • An excitation current delivered from a signal generator 10 is applied to the ends of the primary winding of the first coil 7 and the induced EMF is measured in a high impedance load (10 M.ohms) connected to the secondary winding of the second coil 8.
  • the secondary winding of the first coil (S1) and the primary winding of the second coil (P2) are not used.
  • the output (secondary) from coil 8 is measured on a digital voltmeter 11 in parallel with a coaxial connection to a mini-computer 12.
  • the input and output signals are displayed on a cathode ray oscilliscope 20.
  • the computer, a MINC-11 (DEC) has an input keyboard 13, performs an analog to digital conversion on the as received signal and displays an output on a V.D.U. display screen 14.
  • Figure 4 illustrates an alternative coil arrangement for dealing with specimens which are too large to be accommodated within the confines of a coil.
  • primary and secondary coil windings 15, 16 are dispersed on a horseshoe-shaped coupling member 17, the ends of which define a coupling gap which, in use of the apparatus, bridged by a steel test specimen 18 so that the specimen contribute to the inductive coupling between the primary and secondary windings.
  • the method of classifying steel specimens according to their grade type in accordance with the invention is based on a statistical procedure known as Linear Discriminant Analysis. Computer software packages that perform this statistical technique are available for a range of computer operating systems.
  • grade code a convenient numerical identifier corresponding to the alpha-numeric grade name
  • the discriminant equations can be used to classify each of the steel specimens that form the learning set.
  • the calculated grade may be compared with the known grade to report the percentage of agreements.
  • the values of the variables viz. the inductions of various frequencies, are obtained, and fed into those same discriminant equations that were calculated off line.
  • the grade is unknown, and so the grade name whose equation gives the highest result, is classed as the grade of the unknown specimen.
  • a sampling time of two seconds (2 sees) was used in order to capture the signal induced by each specimen and the RMS signal strength was calculated for each current frequency applied to the input primary coil (from the signal generator). A series of applied current frequencies were used viz;
  • the frequency of the exciting current is slowly increased from zero (by rotating the frequency control potentiometer of the signal generator), the relative phase relationship between the two can be monitored.
  • the input and output signals are exactly out of phase (180°).
  • the introduction of a steel specimen into the coils changes the frequency at which this out of phase condition occurs.
  • the lower frequency measured is called the "natural" frequency and the higher frequency, the "coil” frequency.
  • the computer presents the actual RMS inductions in the secondary at the frequency values used to excite the primary coil and the ACTUAL GRADE CODE it has determined the sample to be.
  • the samples used were all obtained from the laboratory sampling room in the as-rolled condition.
  • the resistance of the primary coil was not matched to that of the signal generator output resistance and consequently the available current into the primary coil varied to a large degree depending on the frequency of the applied current.
  • the induced EMF when no sample was present was measured for the frequencies of interest.
  • Induction at 50hz Total Induction at 50hz - Background (at 50hz) due to sample measured Induction (Relative) (Absolute) (Sample inserted) (No sample)
  • Table 1 of the Appendix shows a computer summary sheet for a portion of the information collected during this investigation.
  • Column 1 of this table indicates the as received sample identification number, 2 the section diameter which is entered via the computer keyboard and columns 3 to 8 refer to the induction (I) at the frequencies indicated.
  • the natural frequency (in hertz) is shown in column 9 and the coil frequency in 10.
  • Column 11 is the actual grade of steel of the specimen.
  • Tables 2 and 3 show the chemical analysis, the inductions and the computed grade classification for a few of the samples tested.
  • the program which collects the voltage waveform from the output coil is also responsible for managing the data which is used for recording new sample, information and also for testing specimens on-line.
  • the data file from this program was transferred to a main processing computer, for analysis by the BMDP discriminant analysis program (P7M).
  • P7M BMDP discriminant analysis program
  • This program is effective to choose which of the pieces of information collecting during testing, known as "attributes", will be most useful in describing the differences between individual specimens classified into their actual grades. For example, the measured induction values at 5,000 hertz may not discriminate well between two particular grade codes whereas the program may find significant differences between the induction values at 5 hertz. It therefore uses the I 5 value in preference to the I 5000 value to separate these two grades. In reality (with 8 attributes and hundreds of samples) the simple two-dimensional separation mentioned above translates into 8th dimensional space.
  • the program uses a weighting procedure to emphasize the extent to which each attribute will be used to get the maximum separation that is possible (i.e. the best discrimination one grade from another) from the supplied data.
  • ⁇ , ⁇ , ⁇ are attributes and a,b,c are constants determined from the statistical analysis.
  • a,b,c once calculated on a reasonable large machine can be entered into a smaller (e.g. MINC - 11 machine) ready for the testing of new samples.
  • X table is searched for the value of X calculated and the grade outputted.
  • the BMDP result file, containing the classification function coefficients was transferred, via floppy diskette, to the MINC-11.
  • the output grade is one of the "generic" grades inputted to the program. For example a sample whose actual grade specification is AS 1302, would be classified to the generic code of SF2 (see Figure 4c, Case No. 36).
  • the BMDP statistical package outputs its results in the form of a classification matrix. This tabulated information is read as follows:
  • entries appear at locations other than on the major diagonal.
  • grade B Of the 10 cases of grade B, 7 are correct, 2 are misclassified as grade A, and one case (1) misclassified as grade C.
  • Table 5 shows the actual matrix obtained as a summary of the results of grade classification on steel rounds (5.5 mm - 20 mm). Another method BMDP uses to describe the results obtained from its statistical analysis is to generate a canonical variable plot. This graph is a two dimensional representation of the relative placement and separations between individual groups (grades). This graph is shown as Figure 5.
  • Higher manganese steels WK22, XK1320, XK1340 are shown as a band extending to the right at a lower position on the graph.
  • Spring steel grades XK5155, XK9261 are shown on the far right and far right bottom respectively indicating the relative ease of separation or classification which can be made for these grades, based on their magnetic properties.
  • the current traverses the entire cross-section of a steel specimen inserted into the coils.
  • the intensity of the current induced is therefore directly related to the cross-sectional area of the specimen (the volume or mass per unit length). At high frequencies (greater than 500 hertz) the current flow is confined almost entirely to the surface or skinof the conductor, as illustrated in Figure 6.
  • the skin or penetration depth from the conductor's surface is given by: ,d being the depth at which the current has fallen to l/e of its surface value.
  • ⁇ o permeability of free space
  • ⁇ permeability of the material
  • f the frequency of the applied current
  • s conductivity of the material
  • the specimen is either a flat or angle (or channel) with a width/thickness ratio of 18/1 or 104 x 5.8 mms for a typical structural grade of steel.
  • Information can be gathered on other sections to form the basis for extending the method to all steel shapes produced at a particular steelworks where testing is to be conducted.
  • Table 8 of the Appendix lists classification function coefficients actually determined for a wide range of steel grades and Tables 9, 10 and 11 show how these were used to classify three separate steel samples of unknown grade.
  • the first sample was a 5.5 mm round section and as indicated in Table 9 each measured variable of the sample was multiplied by the appropriate coefficient and the result summed for all variables. This sum is calculated for all the possible grades and the grade whose sum is the maximum value is deemed to be the actual grade of the specimen.
  • Table 9 the highest value of 12072.895 was obtained from the coefficients for the grade WS1014 which was therefore determined as the appropriate grade.
  • Table 10 shows the results obtained from a second specimen which was 10 mm round.
  • the maximum sum value of 12175.711 was obtained from the coefficients for the grade WS1014 and this specimen was also of that grade.
  • the maximum sum value of 13534.500 was obtained from the coefficients for the grade WK1082 which was therefore determined as the appropriate grade.
  • the third specimen was 10 mm round and the first row of figures relating to section isn the same for Tables 10 and 11.
  • the method of the present invention in which the absolute induction of a steel sample is measured at various applied frequencies is capable of classifying the Specimen into a GRADE CODE which is the primary method of steel identification used both within steelworks and by customers. It allows a rapid means of steel identification and avoids most of the current limitations of the Forster instrumentation.
  • the method can be applied to steel sections of various shapes and it can be usefully employed in the detection and measurement of surface decarburisation.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Pathology (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Physics & Mathematics (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • Food Science & Technology (AREA)
  • Medicinal Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)
  • Investigating Or Analyzing Materials By The Use Of Magnetic Means (AREA)

Abstract

Une éprouvette d'acier est rapprochée de deux enroulements (7, 8) pour établir un couplage inductif entre l'enroulement primaire (7) et l'enroulement secondaire (8). L'enroulement primaire (7) est excité par une pluralité de fréquences par un courant provenant d'un générateur de signaux (10) et les signaux induits, mesurés sous une charge à haute impédance reliée entre l'enroulement secondaire (8), représentent les valeurs d'induction du spécimen à ces fréquences. Le spécimen reçoit ainsi une classification de nuance se fondant sur ces valeurs d'induction. La mesure peut être facilitée par l'utilisation d'un voltmètre numérique (11), d'un mini-ordinateur (12) et d'un oscilloscope à rayons cathodiques (20).
PCT/AU1986/000039 1985-02-15 1986-02-17 Classification de l'acier WO1986004991A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
DE8686901303T DE3674675D1 (de) 1985-02-15 1986-02-17 Klassifizierung von stahl.
KR860700716A KR880700265A (ko) 1985-02-15 1986-10-15 강철 등급 분류 방법 및 장치

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
AUPG931485 1985-02-15
AUPG9314 1985-02-15
AU54600/86A AU589404B2 (en) 1985-02-15 1986-02-17 Classification of steel

Publications (1)

Publication Number Publication Date
WO1986004991A1 true WO1986004991A1 (fr) 1986-08-28

Family

ID=25630516

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/AU1986/000039 WO1986004991A1 (fr) 1985-02-15 1986-02-17 Classification de l'acier

Country Status (2)

Country Link
AU (1) AU589404B2 (fr)
WO (1) WO1986004991A1 (fr)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3930939A1 (de) * 1988-09-16 1990-03-22 Hitachi Ltd Verfahren und vorrichtung zur vorhersage der gueteminderung eines ein anlagenteil bildenden bauteils
GB2378513A (en) * 2001-06-01 2003-02-12 Lattice Intellectual Property Pipe material determination
US7939525B2 (en) 2001-09-27 2011-05-10 Bar-Ilan University Conjugated psychotropic drugs and uses thereof
US8046274B2 (en) 2002-01-25 2011-10-25 Menahem Sevdermish Method for digital color grading of gems and communication thereof
US8207369B2 (en) 2008-02-11 2012-06-26 Ramot At Tel-Aviv University Ltd. Conjugates for treating neurodegenerative diseases and disorders
US8222296B2 (en) 2006-07-17 2012-07-17 Ramot At Tel-Aviv University Ltd. Conjugates comprising a GABA- or glycine compound, pharmaceutical compositions and combinations thereof and their use in treating CNS disorders
US8916610B2 (en) 2010-09-22 2014-12-23 Ramot At Tel-Aviv University Ltd. Acid addition salt of a nortriptyline-GABA conjugate and a process of preparing same
US8975251B2 (en) 2009-12-09 2015-03-10 Bar-Ilan University Methods of improving cognitive functions

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5034690A (en) * 1988-04-01 1991-07-23 Taliaferro Sam W Method and apparatus for quantitatively determining whether at least one of two or more ferromagnetic components is missing from an assembly

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2331418A (en) * 1940-01-08 1943-10-12 George A Rubissow Apparatus for measuring magnetic characteristics of materials
US3434048A (en) * 1964-07-10 1969-03-18 K J Law Eng Inc Eddy current apparatus for testing the hardness of a ferromagnetic material
AU4654679A (en) * 1979-04-27 1980-10-30 Georgetown University Magnetic detection apparatus + method
AU7175681A (en) * 1980-05-06 1981-11-26 Georgetown University Apparatus and method for image reproduction of materials using their magnetic and electric properties
EP0049951A2 (fr) * 1980-10-10 1982-04-21 Exxon Research And Engineering Company Dispositif et procédé pour mesurer la carburation de tubes dans des fours
SU1095058A1 (ru) * 1982-03-24 1984-05-30 Всесоюзный научно-исследовательский и проектный институт тугоплавких металлов и твердых сплавов Вихретоковый способ контрол качества изделий из твердых сплавов
US4475083A (en) * 1977-09-19 1984-10-02 Studsvik Energiteknik Ab Method and apparatus for electromagnetically measuring parameters of electrically conductive high temperature materials
JPS6017350A (ja) * 1983-07-08 1985-01-29 Kawasaki Steel Corp 金属の変態率測定方法

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2331418A (en) * 1940-01-08 1943-10-12 George A Rubissow Apparatus for measuring magnetic characteristics of materials
US3434048A (en) * 1964-07-10 1969-03-18 K J Law Eng Inc Eddy current apparatus for testing the hardness of a ferromagnetic material
US4475083A (en) * 1977-09-19 1984-10-02 Studsvik Energiteknik Ab Method and apparatus for electromagnetically measuring parameters of electrically conductive high temperature materials
AU4654679A (en) * 1979-04-27 1980-10-30 Georgetown University Magnetic detection apparatus + method
AU7175681A (en) * 1980-05-06 1981-11-26 Georgetown University Apparatus and method for image reproduction of materials using their magnetic and electric properties
EP0049951A2 (fr) * 1980-10-10 1982-04-21 Exxon Research And Engineering Company Dispositif et procédé pour mesurer la carburation de tubes dans des fours
SU1095058A1 (ru) * 1982-03-24 1984-05-30 Всесоюзный научно-исследовательский и проектный институт тугоплавких металлов и твердых сплавов Вихретоковый способ контрол качества изделий из твердых сплавов
JPS6017350A (ja) * 1983-07-08 1985-01-29 Kawasaki Steel Corp 金属の変態率測定方法

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of EP0211905A4 *

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3930939A1 (de) * 1988-09-16 1990-03-22 Hitachi Ltd Verfahren und vorrichtung zur vorhersage der gueteminderung eines ein anlagenteil bildenden bauteils
GB2378513A (en) * 2001-06-01 2003-02-12 Lattice Intellectual Property Pipe material determination
US7939525B2 (en) 2001-09-27 2011-05-10 Bar-Ilan University Conjugated psychotropic drugs and uses thereof
US8168628B2 (en) 2001-09-27 2012-05-01 Ramot At Tel-Aviv University Ltd. Conjugated psychotropic drugs and uses thereof
US8283381B2 (en) 2001-09-27 2012-10-09 Ramot At Tel-Aviv University Ltd. Conjugated psychotropic drugs and uses thereof
US8046274B2 (en) 2002-01-25 2011-10-25 Menahem Sevdermish Method for digital color grading of gems and communication thereof
US8222296B2 (en) 2006-07-17 2012-07-17 Ramot At Tel-Aviv University Ltd. Conjugates comprising a GABA- or glycine compound, pharmaceutical compositions and combinations thereof and their use in treating CNS disorders
US8377990B2 (en) 2006-07-17 2013-02-19 Ramot At Tel-Aviv University Ltd. Conjugates comprising a psychotropic drug or a GABA agonist and an organic acid and their use in treating pain and other CNS disorders
US8207369B2 (en) 2008-02-11 2012-06-26 Ramot At Tel-Aviv University Ltd. Conjugates for treating neurodegenerative diseases and disorders
US8722923B2 (en) 2008-02-11 2014-05-13 Ramot At Tel-Aviv University Ltd. Conjugates for treating neurodegenerative diseases and disorders
US8975251B2 (en) 2009-12-09 2015-03-10 Bar-Ilan University Methods of improving cognitive functions
US8916610B2 (en) 2010-09-22 2014-12-23 Ramot At Tel-Aviv University Ltd. Acid addition salt of a nortriptyline-GABA conjugate and a process of preparing same

Also Published As

Publication number Publication date
AU5460086A (en) 1986-09-10
AU589404B2 (en) 1989-10-12

Similar Documents

Publication Publication Date Title
EP0211905B1 (fr) Classification de l'acier
US4763274A (en) Machine implemented analysis eddy current data
US6037768A (en) Pulsed eddy current inspections and the calibration and display of inspection results
Lebrun et al. Pulsed eddy current signal analysis: application to the experimental detection and characterization of deep flaws in highly conductive materials
DK2108120T3 (en) Method and device for non-destructive testing using eddy currents
US4881030A (en) Method and apparatus for measuring and precisely locating internal tensile stresses in hardened regions of components by measuring coercive field strength and barkhausen noise amplitude
US6424151B2 (en) Method and apparatus for evaluation of eddy current testing signal
KR100218653B1 (ko) 전자유도형 검사장치
AU589404B2 (en) Classification of steel
CN1013461B (zh) 对铁磁性工件蠕变损伤的无损检验
CN106537113A (zh) 粒子计数器和分类系统
WO1997030338A1 (fr) Systeme et procede d'analyse rapide de cellules par cytometrie spectrale
Wincheski et al. Self-nulling eddy current probe for surface and subsurface flaw detection
EP0531042A2 (fr) Système et méthode pour l'évaluation des caractéristiques de la surface d'un matériau magnétique
Chady et al. Optimization of eddy-current sensor for multifrequency systems
Faurschou et al. Pulsed eddy current probe optimization for steel pipe wall thickness measurement
Witos Properties of amplitude distributions of acoustic emission signals generated in pressure vessel during testing
JPS62273447A (ja) 材料劣化度測定方法及びその装置
Bartels et al. Multifrequency eddy current image processing techniques for nondestructive evaluation
US7131343B2 (en) Method of measuring density properties of a particle distribution
CA2027968C (fr) Procede et dispositif d'inspection de tubes
CN1128359C (zh) 多频多通道轧辊涡流检测仪
US6963822B1 (en) Method and apparatus for separation, analysis and evaluation of data
JP2000131287A (ja) 磁気計測による探傷方法及び装置
Capobianco Field mapping and performance characterization of commercial eddy current probes

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AU JP KR US

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): AT BE CH DE FR GB IT LU NL SE

WWE Wipo information: entry into national phase

Ref document number: 1986901303

Country of ref document: EP

WWP Wipo information: published in national office

Ref document number: 1986901303

Country of ref document: EP

WWG Wipo information: grant in national office

Ref document number: 1986901303

Country of ref document: EP