超聲波探傷論文 超聲波探傷畢業(yè)論文

1、II處相鄰兩缺陷在一直線上，其間距為11mm，小于12mm，作為一條缺陷處理。以兩缺陷長度和作為其指示長度，即33mm。5.3 超聲探傷缺陷評定 承壓設(shè)備對接焊接接頭檢測一般用B級檢測技術(shù)。由4.2.2中摘錄的GB11345-89標(biāo)準(zhǔn)中關(guān)于缺陷評定的敘述及表5-2可的缺陷級別評定如表6-2所示。表5-2 缺陷級別評定缺陷 = 1 * ROMAN I = 2 * ROMAN II = 3 * ROMAN III級別 = 4 * ROMAN IV = 4 * ROMAN IV = 4 * ROMAN IV 由表5-2可知，板材共存在三處缺陷，等級均為 = 4 * ROMAN IV，不符合合格級別，

2、應(yīng)進(jìn)行焊縫返修。結(jié)論科技在發(fā)展，焊縫無損檢測技術(shù)也在向著自動化、智能化和信息化的方向發(fā)展。但是，我們也應(yīng)看到，針對我國當(dāng)前的實際情況，手動人工超聲波探傷仍是主要的探傷方法，且應(yīng)用依然相當(dāng)廣泛。并且在實際的超聲波探傷過程中，仍在不斷涌現(xiàn)許多新問題。針對這些實際問題，在指導(dǎo)老師的悉心指導(dǎo)下，在前人成果的基礎(chǔ)上，本文對焊接缺陷的超聲波探傷技術(shù)進(jìn)行了詳細(xì)介紹，并通過鋼板焊縫的超聲波探傷實驗詳細(xì)講述了超聲波探傷的操作步驟、注意事項和等級評定標(biāo)準(zhǔn)。本課題著重做了以下工作：論述了過程設(shè)備制造工藝流程，并詳細(xì)介紹了焊接過程中常見的缺陷和產(chǎn)生缺陷的原因。詳細(xì)講述了超聲波探傷技術(shù)的原理、分類、評定等級和評定標(biāo)準(zhǔn)。

3、結(jié)合實驗詳細(xì)介紹了超聲波探傷的操作步驟和注意事項，并對給定板材焊縫進(jìn)行了現(xiàn)場探傷和等級評定，完成了焊縫超聲檢測報告和焊縫超聲檢測工藝卡。焊縫超聲波檢測作為檢驗焊縫質(zhì)量的一種有效方法，其檢測的可靠性和有效性還待進(jìn)一步完善。由于超聲檢測的本身所固有的特點和局限性，在實際的無損檢測中還須與其他檢測方法配合使用。我們堅信，隨著研究工作的進(jìn)一步深入，此問題將會不斷完善。參考文獻(xiàn)1鄒廣華，劉強(qiáng)過程裝備制造與檢測北京：化學(xué)工業(yè)出版社，2003，7.32522鄧輝，林樹青.超聲檢測.第二版.北京：中國勞動社會保障出版社，2008.353鄭津洋，董其伍，桑芝富.過程設(shè)備設(shè)計.北京：化學(xué)工業(yè)出版社，2005，5.

4、91954曹玉華. 焊接質(zhì)量的超聲波探傷無損檢測.寧夏機(jī)械，2008，4：7375 5單寶華,喻言,歐進(jìn)萍.超聲相控陣檢測技術(shù)及其應(yīng)用.無損檢測，2004，26（5）：2352386于建軍.焊縫的超聲波檢測技術(shù)研究.碩士學(xué)位論文.新疆：新疆農(nóng)業(yè)大學(xué)，2005致謝本畢業(yè)設(shè)計是在胡效東老師的精心指導(dǎo)和下完成的。值此論文完成之際，謹(jǐn)向胡老師及過控系各位老師致以最崇高的敬意和衷心的感謝！很慶幸自己在求學(xué)階段遇到這樣好的老師，師恩難忘。衷心感謝實驗室劉梅老師給予我的指導(dǎo)和幫助。衷心感謝我的同學(xué)在論文的撰寫和答辯的準(zhǔn)備工作中給予我的熱情的幫助。感謝山東科技大學(xué)為我們提供的良好的學(xué)習(xí)和生活環(huán)境。 最后，向?qū)?/p>

5、閱本文的老師致以深深的敬意，并再一次真誠的感謝所有關(guān)心、幫助過我的老師、同學(xué)和朋友們! 在此，謹(jǐn)向你們致以最崇高的敬禮，謝謝！附錄英文文獻(xiàn)1.BASIC ULTRASONIC PRINCIPLESa.What is Ultrasound?Sound generated above the human hearing range (typically 20KHz) is called ultrasound. However, the frequency range normally employed in ultrasonic nondestructive testing and thickne

6、ss gaging is 100KHz to 50MHz. Although ultrasound behaves in a similar manner to audible sound, it has a much shorter wavelength. This means it can be reflected off very small surfaces such as defects inside materials. It is this property that makes ultrasound useful for nondestructive testing of ma

7、terials.The Acoustic Spectrum in Figure (1) breaks down sound into 3 ranges of frequencies. The Ultrasonic Fig.1b. Frequency, Period and WavelengthUltrasonic vibrations travel in the form of a wave, similar to the way light travels. However, unlike light waves, which can travel in a vacuum (empty sp

8、ace), ultrasound requires an elastic medium such as a liquid or a solid. Shown in Figure (2) are the basic parameters of a continuous wave (cw). These parameters include the wavelength ()and the period (T) of a complete cycle.b.Frequency,Period and WavelengthUltrasonic vibrations travel in the form

9、of a wave,similar to the way light travels.However,unlike light waves,which can travel in a vacuum (empty space),ultrasound requires an elastic medium such as a liquid or a solid.Shown in Figure(2)are the basic parameters of a continuous wave(cw).These parameters include the wavelength() and the per

10、iod(T)of a complete cycle.The number of cycles completed in one second is called frequency(f)and is measured in Hertz(Hz),some examples follow; 1 cycle/second= 1Hz 1000 cycles/second= 1KHz 1,000,000 cycles/second= 1MHzThe time required to complete a full cycle is the period (T), measured in seconds.

11、 The relation between frequency and period in a continuous wave is given in Equation (1).Eqn. 1 f = 1/Tc.Velocity of Ultrasound and WavelengthThe velocity of ultrasound (c) in a perfectly elastic material at a given temperature and pressure is constant. The relation between c, f, and T is given by E

12、quations (2) and (3):Eqn. 2 = c/f Eqn. 3 = cT = Wavelengthc = Material Sound Velocityf = FrequencyT = Period of timeTable 1 on page 40 lists the longitudinal and shear wave velocities of materials that are commonly tested with ultrasonics.d.Wave Propagation and Particle MotionThe most common methods

13、 of ultrasonic examination utilize either longitudinal waves or shear waves.Other forms of sound propagation exist,including surface waves and Lamb waves.The longitudinal wave is a compressional wave in whichthe particle motion is in the same direction as the propagation of the wave.The shear wave i

14、s a wave motion in which the particle motion is perpendicular to the direction of the propagation.Surface(Rayleigh)waves have an elliptical particle motionand travel across the surface of a material.Their velocity isapproximately 90%of the shear wave velocity of the materialand their depth of penetr

15、ation is approximately equal toone wavelength.Plate(Lamb)waves have a complex vibration occurring inmaterials where thickness is less than the wavelength ofultrasound introduced into it.Figure(3)provides an illustration of the particle motion versus the direction of wave propagation for longitudinal

16、 waves and shear waves.e.Applying UltrasoundUltrasonic nondestructive testing introduces high frequency sound waves into a test object to obtain information about the object without altering or damaging it in any way.Two basic quantities are measured in ultrasonic testing;they are time of flight or

17、the amountof time for the sound to travel through the sample and amplitude of received signal.Based on velocity and round trip time of flight through the material the material thickness can be calculated as follows:Eqn.4 T=Material Thicknessc=Material Sound Velocity=Time of FlightMeasurements of the

18、 relative change in signal amplitude can be used in sizing flaws or measuring the attenuation of a material.The relative change in signal amplitude is commonly measured in decibels.Decibel values are the logarithmic value of the ratio of two signal amplitudes.This can be calculated using the followi

19、ng equation.Some useful relationships are also displayed in the table below;Eqn.5 dB=20log10(A1/A2)dB=DecibelsA1=Amplitude of signal 1A2=Amplitude of signal 2f.Sensitivity and ResolutionSensitivity is the ability of an ultrasonic system to detect reflectors (or defects)at a given depth in a test mat

20、erial.The greater the signa that is received from thesereflectors,the more sensitive the transducer system.Axial resolution is the ability of an ultrasonic system to produce simultaneous and distinct indications from reflectors Iocated at nearly the same position with respect to the sound beam.Near

21、surface resolution is the ability of the ultrasonic system to detect reflectors located close to the surface of the test piece.2.ADVANCED DEFINITIONS AND FORMULASa.Transducer waveform and spectrumTransducer waveform and spectrum analysis is done according to testconditions and definitions of ASTM E1

22、065.Typical units are MHz for frequency analysis,microseconds for waveform analysis,and dB down from peak amplitude.Figure(4)illustrates waveform duration at the 14dB level or 20%amplitude of peak.The-40dB waveform duration corresponds to 1%amplitude of peak.Figure(5)illustrates peak frequency,upper

23、 and lower-6dB frequencies and MHz bandwidth measurements.The relation between MHz bandwidth and waveform duration is shown in Figure(6).The scatter is wider at-40dB because the 1%trailing end of the waveform contains very little energy and so has very little effect on the analysis of bandwidth.Beca

24、use of the scatter it is most appropriate to specify waveforms in the time domain (microseconds)and spectrums in the frequency domain.The approximate relations shown in Figure(6)can be used to assist in transducer selection.For example,if a-14dB waveform duration of one microsecond is needed,what fr

25、equency transducer should be selected?From the graph,a bandwidth of approximately 1 to 1.2MHz corresponds to approximately 1 microsecond-14dB waveform duration.Assuming a nominal 50%fractional bandwidth transducer, this calculates to a nominal center frequency of 2 to 2.4MHz.Therefore,a transducer o

26、f 2.25MHz or 3.5MHz may be applicable.b.Acoustic Impedance,Reflectivity, and AttenuationThe acoustic impedance of a material is the opposition to displacement of its particles by sound and occurs in many equations.Acoustic impedance is calculated as follows:Eqn.6 Z=cZ=Acoustic Impedancec=Material So

27、und Velocity=Material DensityThe boundary betweeen two materials of different acoustic impedances is called an acoustic interface.When sound strikes an acoustic interface at normal incidence,some amount of sound energy is reflected and some amount is transmitted across the boundary.The dB loss of en

28、ergy on transmitting a signal from medium 1 into medium 2 is given by:Eqn.7a dB loss=Z1=Acoustic Impedance of First MaterialZ2=Acoustic Impedance of Second MaterialThe dB loss of energy of the echo signal in medium 1 reflecting from an interface boundary with medium 2 is given by:Eqn.7b dB loss=For

29、example:The dB loss on transmitting from water(Z=1.48)into 1020 steel(Z=45.41)is -9.13dB;this also is the loss transmitting from 1020 steel into water.The dB loss of the backwall echo in 1020 steel in water is-0.57dB;this also is the dB loss of the echo off 1020 steel in water.The waveform of the ec

30、ho is inverted when Z2Z1.Finally,ultrasound attenuates as it progresses through a medium. Assuming no major reflections,there are three causes of attenuation: diffraction,scattering and absorption.The amount of attenuation through a material can play an important role in the selection of a transduce

31、r for an application.c.Sound FieldThe sound field of a transducer is divided into two zones;the near field and the far field.The near field is the region directly in front of the transducer where the echo amplitude goes through a series of maxima and minima and ends at the last maximum,at distance N

32、 from the transducer.The location of the last maximum is known as the near field distance (N or)and is the natural focus of the transducer.The far field is the area beyond N where the sound field pressure gradually drops to zero.Because of the variations within the near field it can be difficult to

33、accurately evaluate flaws using amplitude based techniques. The near field distance is a function of the transducer frequency, element diameter,and the sound velocity of the test material as shown by Equation 8:Eqn.8 Eqn.8a N=Near Field DistanceD=Element Diameterf=Frequencyc=Material Sound Velocity=

34、Wavelength(Table 2 on page 40 lists the near field distances in water for manycombinations of transducer frequency and element diameter.)3.Desing cgaracteristics of transducersa.What is an Ultrasonic Transducer?A transducer is any device that converts one form of energy to another.An ultrasonic tran

35、sducer converts electrical energy to mechanical energy,in the form of sound,and vice versa. The main components are the active element,backing,and wear plate.b.The Active ElementThe active element,which is piezo or ferroelectric material, converts electrical energy such as an excitation pulse from a

36、 flaw detector into ultrasonic energy. The most commonly used materials are polarized ceramics which can be cut in a variety of manners to produce different wave modes. New materials such as piezo polymers and composites are also being employed for applications where they provide benefit to transduc

37、er and system performance.c.BackingThe backing is usually a highly attenuative,high density material that is used to control the vibration of the transducer by absorbing the energy radiating from the back face of the active element. When the acoustic impedance of the backing matches the acoustic imp

38、edance of the active element,the result will be a heavily damped transducer that displays good range resolution but may be lower in signal amplitude.If there is a mismatch in acoustic impedance between the element and the backing,more sound energy will be reflected forward into the test material.The

39、 end result is a transducer that is lower in resolution due to a longer waveform duration,but may be higher in signal amplitude or greater in sensitivity.d.Wear PlateThe basic purpose of the transducer wear plate is to protect thetransducer element from the testing environment.In the case of contact

40、 transducers,the wear plate must be a durable and corrosion resistant material in order to withstand the wear caused by use on materials such as steel. For immersion,angle beam,and delay line transducers the wear plate has the additional purpose of serving as an acoustic transformer between the high

41、 acoustic impedance of the active element and the water,the wedge or the delay line all of which are of lower acoustic impedance.This is accomplished by selecting a matching layer that is 1/4 wavelength thick(/4)and of the desired acoustic impedance (the active element is nominally 1/2 wavelength).T

42、he choice of the wear suface thickness is based upon the idea of superposition that allows waves generated by the active element to be in phase with the wave reverberating in the matching layer as shown in Figure(4). When signals are in phase,their amplitudes are additive,thus a greater amplitude wa

43、ve enters the test piece.Figure(12)shows the active element and the wear plate,and when they are in phase.If a transducer is not tightly controlled or designed with care and the proper materials and the sound waves are not in phase,it causes a disruption in the wavefront.英文文獻(xiàn)譯文超聲波的基本原理a什么是超聲波？超出人類聽覺

44、范圍的聲波（通常高于20KHZ）稱為超聲波。然而用于超聲無損檢測及厚度測量的超聲波頻率范圍通常是50100KHz。雖然超聲波的表現(xiàn)方式與聲波類似，但它的波長很短。這意味著它可以反映很小的表面，如材料內(nèi)部的缺陷。正是這一特性使得超聲波在無損檢測中得到了廣泛的應(yīng)用。如圖1，聲波頻譜圖可分為3個范圍。超聲波又可進(jìn)一步分為3部分。頻率、周期及波長 超聲波波形的振動傳播方式與光波的傳播方式類似。然而不同于光波可以在真空中傳播，超聲波的傳播需要一種彈性介質(zhì)，如液體或固體。如圖（2）是連續(xù)波的基本參數(shù)。這些參數(shù)包括波長和周期。一秒內(nèi)完成的周期數(shù)稱為頻率，用Hz為單位計量。如下幾個例子：1周期/秒=1Hz10

45、00周期/秒=1KHz1,000,000周期/秒=1MHz完成一個整波所用的時間稱為周期，用秒為單位。周期和頻率的關(guān)系如連續(xù)波方程（1）所示。方程.1 1f =1/T超聲波波速和波長超聲波波速(c)在理想的彈性材料，特定溫度和特定壓力下是不變的。C、f、和T之間的關(guān)系如方程2，3所示：方程.2 =c/f方程.3 =cT=波長c =材料聲速f=頻率T =周期40頁附表一列出了經(jīng)常使用超聲波檢測的材料的縱波和橫波波速。波的傳播和粒子的運動超聲波檢測探傷最常用的是縱波探傷和橫波探傷。同時朝聲檢測中也存在其他類型的波。包括表面波和蘭姆波。(1)縱波是指傳播方向和介質(zhì)粒子振動方向相同的波。橫波是指傳播方

46、向和介質(zhì)粒子振動方向垂直的波。表面波瑞)(一個橢圓質(zhì)點運動和穿越表面形成一層材料他們的速度大約90%的剪切波速的資料他們的穿透深度,大約等于一個波長。 (4)板波發(fā)生在一個復(fù)雜的振動在材料的厚度小于波長超聲引入。圖(3)展示了一個質(zhì)點運動與方向的縱向波和波傳播的橫波傳播速度快。a.超聲波的應(yīng)用介紹了超聲無損檢測高頻聲波進(jìn)入測試對象來獲取信息的對象不改變或損壞以任何方式兩個基本量測的超聲波檢測;他們的飛行時間或時間對于聲音穿越樣品和振幅對接收信號一種基于速度往返傳播時間通過物質(zhì)材料厚度計算方式如下:方程.4 T =材料的厚度,c =材料聲速傳播時間。測量的相對變化信號振幅可用于測量尺寸瑕疵或衰減

47、的材料在信號幅值的相對變化通常是用分貝表示分貝值對數(shù)比的兩種信號振幅這可以用下面的公式計算出一些有用的關(guān)系也顯示在表。方程.5 dB = 20log10(A1 / A2)。dB =分貝,A1 =振幅的信號1 A2 =振幅的信號2b.靈敏度和分辨率 靈敏度是一種超聲檢測諧振(或缺陷)在某一特定深度對測試材料更多的信號,收到這些反射更敏感的傳感系統(tǒng)。 軸分辨率超聲波體系的能力產(chǎn)生同步和鮮明標(biāo)志Iocated從反射幾乎相同的位置時的聲音柱。 近近場的判斷是有能力的超聲波檢測反光位于靠近被檢測面的測試片。附加的定義和公式a.傳感器波形及頻譜 傳感器波形及頻譜分析是根據(jù)試驗條件和定義的ASTM E1065典型的單位。兆赫頻率分析的基礎(chǔ)上,進(jìn)行了分析,并對波形微秒的數(shù)據(jù)庫從amplitude.Figure高峰期間(4),說明了在14dB波形的峰值水平或20%amplitudeThe-40dB 1%amplitude對應(yīng)的波形持續(xù)peak.Figure(5),上部和lower-6dB峰頻率測量頻率和兆赫帶寬兆赫之間的關(guān)系的帶寬和波形時間是顯示在圖(6).由于廣at-40dB散這個1%trailing結(jié)束的波形只含有少量的能源等幾乎沒有影響分析的帶寬因為它是最合適的分散在指定的時