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Radiographic Testing Pdf 87095 | Ultrasonic Testing

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                           ULTRASONIC TESTING 
                            OF STEEL CASTINGS 
                                   by 
                              J . D . Lavender 
                       Research Manager. Quality Assurance 
                                              Group 
                       Steel Castings Research & Trade Association 
                              Sheffield. England 
                           TABLE 
                                 OF CONTENTS 
                                                       Page 
              Preface .................................................................................................................. 2 
              Theory of Ultrasonic Flaw Detection ...................................................................... 3 
              Calibration of the Ultrasonic Instrument ................................................................ 7 
                Calibration and Reference Blocks ................................................................. 7 
                               ............................................................................. 7 
                Longitudinal Wave Probes 
                Transverse Wave Probes 
                              ............................................................................. 10 
                Measurement of Steel Thickness ................................................................. 12 
             Formation of Casting Defects-Ultrasonic and 
             Radiographic Correlation ...................................................................................... 13 
                Flaws from Inadequate Feeding. Macro-. Filamentary-. 
                Micro-Shrinkage ............................................................................................ 13 
                                             ................................... 14 
                Flaws from Hindered Contraction. Hot Tears. Cracks 
                                              .............................. 19 
                Flaws from Gas and Entrapped Air. Airlocks. Gas Holes 
              Ultrasonic Attenuation - Carbon. Low Alloy and Austenitic Steels ........................ 22 
                Influence of Structure on Ultrasonic Attenuation ........................................... 22 
                Measurement of Ultrasonic Attenuation ........................................................ 24 
              Sizing of Flaws and Acceptance Standards .......................................................... 27 
                Beamspread and Maximum Amplitude Techniques ...................................... 27 
                Surface Flaws ................................................................................................ 30 
                Beamspread from Transverse Wave Probes 
                                        ................................................. 31 
              Production and Economics of an Ultrasonic Technique ........................................ 33 
              References ............................................................................................................. 36 
                   © by Steel Founders' Society of America, 1976 
                        CAST METALS FEDERATION BUILDING 
                           20611 CENTER RIDGE ROAD 
                                RIVER, OHIO 44116 
                           ROCKY 
                        Printed in the United States of America 
                                   1 
               J. D. Lavender was educated at Ecclesfield Grammar School, Nr. Shef- 
            field. He received the Associateship of the Institution of Metallurgists 
            in 1954 and became a Fellow in 1972. He is a member of the Institute 
            of Physics and of the British Institute of Nondestructive Testing. He was 
                                     1940 to 1946 on 
            employed by Brown-Firth Research Laboratories from 
                  of non-f errous and ferrous alloys, X-ray crystallography and 
            radiography 
                   of low and high alloy steels. 
            metallography 
                1954 he became foundry metallurgist with Firth-Vickers Stainless 
               In 
                        1957 moved to the Steel Castings Research and 
            Steels in Sheffield, and in 
                            as a senior investigator of nondestructive 
            Trade Association (S.C.R.A.T.A.) 
            testing. He was made section head in 
                              1964 and research manager of 
            quality assurance in 1972. Mr. Lavender has presented the S.C.RA.T.A. 
                     at the National Technical and Operating Conference 
            Exchange Lecture 
                                1969 and 1975. 
            of the Steel Founders’ Society of America in 
                                                           PREFACE 
               Ultrasonic flaw detection is a method of non-              was published in 1970. This specification was 
                                                                          followed in 1974 by the ASME Boiler 
             destructive testing that is finding increasing ac-                                                 & Pressure 
             ceptance in the United States. This growth in                Vessel Code, Section V, T524.2, “Angle Beam 
             the application of ultrasonics is intimately tied to         Examination of Steel Castings.” Other specifica- 
             the field of fracture mechanics and the scientifi-           tions of international importance are the West- 
             cally based approaches to designing against fail-            inghouse Specification 600964, “Ultrasonic Testing 
             ure. Ultrasonic flaw detection, as opposed to the            of Steel Castings,” and the Central Electricity 
             more widely used radiography, permits the in-                Generating Board United Kingdom Standard 
             spector to pinpoint accurately the location of the           66011, “Turbine Castings (chromium, molyb- 
                                                                                                    .” 
             flaw and to determine its shape and size. These              denum, vanadium steel) 
             factors play an important role in fracture mechan-              Increased acceptance and utilization of ultra- 
             ics where the maximum safe stresses can be cal-              sonic inspection are to be expected for the future. 
             culated for a given flaw size and location. Con-             These trends are apparent from the extensive 
             versely, for a given flaw type, size and operating           activity going on now in the United States and 
             stress field, the maximum flaw size that can be              abroad. Three standards, in addition to ASTM 
             tolerated safely can be determined. Thus the                 A-609, are currently considered. These are the 
             unique ability of ultrasonic inspection to assess            British IS0 Standard-“Draft Proposal for an 
             flaw location and flaw geometry 
                                              is vital to engi-           International Standard for the Ultrasonic Inspec- 
             neering approaches of fracture-safe design.                  tion of Steel Castings,” the German standard- 
               Further insight into the growth of nondestruc-             “Introduction of Ultrasonic Testing and Stand- 
                                      a historical review of 
             tive testing is gained by                                    ards and General Conditions of Delivery for Steel 
             developments. Radiography was developed early                Castings,” and a new proposed ASTM specifica- 
             and achieved industrial status when a set of radio-          tion which will be similar to Westinghouse Speci- 
             graphs called, “Gamma Ray Radiographic Stand-                fication 600964. 
             ards for Steam Pressure Service” was issued in 
             1938 by the Bureau of Engineering, U.S. Navy.                   This booklet is published to present basic in- 
             Numerous ASTM specifications relative to radio-              formation on the nature of ultrasonic inspection 
                                                            is- 
             graphy in steel casting production have been                 principles with specific guidelines on flaw detec- 
             sued since then. Ultrasonics, in contrast, received           tion in steel castings. This information and the 
             its first major boost towards industrial application          favorable economic aspects of flaw detection by 
             for steel castings in Britain when a study on its             ultrasonic means are presented for technical per- 
             use and development possibilities was undertaken              sonnel and managers of casting producers and 
             in 1958. ASTM specification A-609, “Standard                  particularly the technical staff of casting users 
             Specification for Longitudinal Beam Ultrasonic                who control the level to which ultrasonic inspec- 
                                   & Low Alloy Steel Castings” 
             Inspection of Carbon                                          tion will find acceptance in the future. 
                                                                                           PETER F. WIESER 
                                                                                            Research Director 
                                                                                           By direction of the 
                                                                                         Carbon and Low Alloy 
                                                                                     Technical Research Committee 
                                                                                       H. J. SHEPPARD, Chairman 
                                                                                A. G. LINLEY                      P. J. NEFF 
                                                                                F. H. HOHN                  A. J. WHITTLE 
                                                                                L. H. LONG, JR              R. A. MILLER 
                                                                       2 
                           THEORY OF ULTRASONIC FLAW DETECTION 
        THE CHARACTERISTICS OF SOUND WAVES 
          Sound is produced when a body vibrates and is 
        propagated only within a medium. Sound waves 
        are classified in terms of frequency, which is the 
        number of vibrations per second 
                                or Hertz; the 
        frequency scale relating the sonic and ultrasonic 
                      Fig. 1. 
        ranges is shown in 
          The basic formula, to which reference is made 
        throughout the whole study of ultrasonic examina- 
        tion, is: 
        The relationship between frequency and wave- 
        length for the transmission of ultrasonic waves 
        in steel is given in Fig. 2. 
          Sound waves must have a medium in which to 
        travel and the velocities with which they are 
        transmitted through a particular medium depends 
        on its elastic constants and on its density, as given 
        by the following formulae: 
        Thin rod velocity 
        Longitudinal wave velocity 
        Transverse wave velocity 
        where 
        c =wave velocity, mm/s 
                                        2
        E =Young’s modulus of elasticity, dynes/mm  
                                      2
        G= shear modulus of elasticity, dynes/mm  
                    3
        ϕ =density, g/mm  
        σ =Poisson’s ratio 
          Values 
               of sound velocity, density and acoustic 
        impedance of materials associated with ultrasonic 
        examination are given in Table I. The wavelengths 
        of longitudinal and transverse waves in steel are 
        given in Table 
                   II.
                                                 3 
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...Ultrasonic testing of steel castings by j d lavender research manager quality assurance group trade association sheffield england table contents page preface theory flaw detection calibration the instrument and reference blocks longitudinal wave probes transverse measurement thickness formation casting defects radiographic correlation flaws from inadequate feeding macro filamentary micro shrinkage hindered contraction hot tears cracks gas entrapped air airlocks holes attenuation carbon low alloy austenitic steels influence structure on sizing acceptance standards beamspread maximum amplitude techniques surface production economics an technique references founders society america cast metals federation building center ridge road river ohio rocky printed in united states was educated at ecclesfield grammar school nr shef field he received associateship institution metallurgists became a fellow is member institute physics british nondestructive to employed brown firth laboratories non f e...

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