1、1Nondestructive Material Testing with Ultrasonics使用超声波对材料进行的非破坏性检测Introduction to the Basic Principles基本原理介绍UNION ELECTRIC STEEL CORPORATION美国联合电钢（戴维）轧辊公司安多利国际有限公司翻译2007年 3月 06日2Contents 内容安多利国际有限公司Introduction介绍 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2、 41. Why use ultrasonics for nondestructive material testing? 为 什 么 使 用 超声波进行非破坏性材料检测？ . . . . . . . . . . .5 2. Ultrasonic testing tasks 超声波检测任务 . . . . . . . . . . . . . . . . . . . . . . . 53. Detection of discontinuities 不 连 续 的 发 现 . . . . . . . . . . . . . . . . . . . . . . 64. Method of testi
3、ng and instrument technology 检 测 方 法 和 仪 器 技 术 . . . 104.1 The ultrasonic flaw detector 超声波裂纹检测仪 . . . . . . . . . . . . . . . . . . . . 104.2 Near resolution . 近 场 的 处 理 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154.3 The probe 探 头 . . . . . . . . . . . . . . . . . . . . .
4、 . . . . . . . . . . . . . . . . . . . . . . . 164.4 Refraction and mode conversion 折射和模式的转变 . . . . . . . . 174.5 Characteristics of angle-beam probes角度探头的特性 . . . . . . . . . . . . . . . . . . 194.6 The TR probe TR探 头 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5、. 205. Locating discontinuities 断 裂 的 定位 . . . . . . . . . . . . . . . . . . . . . . . . . . 225.1 Calibration of the instrument 仪器校准 . . . . . . . . . . . . . . . . . . . . . . . 225.1.1 Calibration with a straight-beam probe平行光 束探头的校准 . . . . . . . . . . . . . . . . . . . 225.1.2 Calibration with
6、a TR probe TR探 头 的校准 . . . . . . . . . . . . . . . . . . . . . . . 245.1.3 Calibration with an angel-beam probe 角度探头的 校准 . . . . . . . . . . . . . 265.1.4 Locating reflectors with an angle-beam probe 使用角度探头对反射器进行定位 . . 286. Evaluation of discontinuities 断 裂 的 评 估 . . . . . . . . . . . . . . . . . .
7、. . . . 296.1 Scanning method 扫描方法 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 296.2 Evaluation of small discontinuities: The DGS method 对 小 断 裂 的 评 估 ： DGS方 法 . . . . . 306.3 Sound attenuation 消音 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
8、46.4 The reference block method 叁考程序块方法 . . . . . . . . . . . . . . . . . . . . . . 346.4.1 Comparison of echo amplitudes 回声振幅的比较 . . . . . . . . . . . . . . . . . . . . 346.4.2 Distance amplitude curve 振幅曲线的距离 . . . . . . . . . . . . . . . . . . . . . . . . . 357. Documentation 文件 . . . . . . . . .
9、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 378. Diagnosis of indications (outlook)指示的分析诊断 . . . . . . . . . . . . . . . . . . . . . . 40Reference list 参考清单 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 413前 言因时间仓促，加之专业技术欠缺，本译文一定会有很多不准确的地方。我们在此敬
10、请各位读者给予指正和谅解。Introduction 介绍Nondestructive material testing with ultrasonics is more than 40 years old. From the very first examinations, using ultrasonic oscillations for detection of flaws in different materials, it has become a classical test method based on measurements with due regard to all th
11、e important influencing factors. Today it is expected that ultrasonic testing, supported by great advances in instrument technology, give reproducible test results within narrow tolerances. This assumes exact know- ledge of the influencing factors and the ability to apply these in testing technolo g
12、y.使用超声波对材料进行非破坏性检测已经有40多年了。从第一次使用超声波振动检测不同材料上的裂纹开始，它已经成为考虑到所有重要影响因素的一个典型的测试方法。 今天具有更先进技术的超声波检测，能够在精密的误差中反复获得的测验结果。影响因素的精确知识和能力被运用到测试技术中 。 Not all influences have to be seriously regarded by the operator.。 In many cases some of the influences can be neglected（忽视） without exceeding（超过） the permitted m
13、easurement tolerances（测量公差） . Due to this, the test sequence is simplified and the testing time reduced. Despite this, the future belongs to the qualified operator who carries out his task responsibly and who continuously endeavours to（争取） keep his knowledge at the latest state of the art操作者不需要将所有的影
14、响都看得很严重。很多情况下，如果一些影响没有超过允许的测量误差时，可以被忽略不计。正由于这样，测试序列被单一化并可减少测试的时间。不在乎这些，未来是属于负责任地进行本工作的合格操作员和不断地努力把他的知识留在本行业的新人。 1. Why use ultrasonics for nondestructive material testing? 为什么使用超声波进行非破坏性材料测试At the beginning of the fifties the technician only knew radiography (x-ray or radioactive isotopes) as a meth
15、od for detection of internal flaws in addition to the methods for nondestructive testing of material surfaces, e.g. the dye penetrant and magnetic particle method. After the Second World War the ultrasonic method, as described by Sokolov in 1935 and applied by Firestone in 1940, was further develope
16、d so that very soon instruments were available for ultrasonic testing of materials.开始时除了这种方法以外,50名技术员只知道使用X光线照相术（照X光、放射性同位素）等对内部裂纹进行非破坏性材料测试。举例来说，着色探伤检测和磁粉检测。 第二次世界大战后， 1935年 Sokolov首先对超声波检测进行了描述， 1940年 Firestone开始运用超声波检测技术。超声波检测技术的应用迅速促使探伤仪器的发展。The ultrasonic principle is based on the fact that sol
17、id materials are good conduc tors（导体）of sound waves. Where by the waves are not only reflected at the interfaces but also by 4internal flaws (material separations, inclusions etc.). The interaction effect of sound waves with the material is stronger the smaller the wave length, this means the higher
18、 the frequency of the wave.超声波检测基于固体材料是声波良好导体的事实 。这里声波不仅能被接触面反射出来，同样也能被内部的裂纹反射回来（材料缺口、内含物等）。声波与材料的相互作用效果越强，波长越短，波的频率越高。 = C/fc = Sound velocity km/s 声 速f = Frequency MHz频率 = Wave lenght mm波长This means that ultrasonic waves must be used in a frequency range between about0.5 MHz and 25 MHz and that th
19、e resulting wave length is in mm. With lower frequencies, the interaction effect of the waves with internal flaws would be so small that detection becomes questionable. Both test methods, radiography and ultrasonic testing, are the most frequently used methods of testing different test pieces for in
20、ternal flaws, partly covering the application range and partly extending it.超声波频率必须在 0.5-25 兆赫间，产生的波长在毫米中。低频率时。波与材料相互作用会非常小，导致无法发现问题。放射线和超声波检测的方法都被经常用于检测不同的测试物体中的裂纹 ，并且被部分的扩充和覆盖了使用范围。This means that today many volume tests are possible with the more economical and non-risk ultrasonic test method, on
21、 the other hand special test problems are solved, the same as before, using radiography. In cases where the highest safety requirements are demanded (e.g. nuclear power plants, aerospace industry) both methods are used.这意味着今天的许多物体的测试，可以采用更经济而且更安全的超声波测试方法,另一方面和以前一样专业的测试问题的解决也可以使用 X 射线照相术。如果哪里有更高的安全需求
22、，也可以同时采用两种方法(举例来说核能发电厂, 航天工业)。2. Ultrasonic testing tasks超声波检测任务Is there a primary classification of tasks assigned to the ultrasonic operator? If we limit ourselves to testing objects for possible material flaws then the classification is as follows:有对超声波操作员指定工作进行主要分类吗? 如果我们因材料缺点原因，限制了对物体的测试, 那么分类是
23、依下列各项:1. Detection of reflectors 寻找反射体2. Location of reflectors 定位反射体3. Evaluation of reflectors评估反射体4. Diagnosis of reflectors反射体分析(reflector type, orientation, etc.反射体类型、方位等 ) Instead of using the word “reflector“, the ultrasonic operator very often uses the term “discontinuity“. This is defined a
24、s being an “irregularity in the test object which is suspected as being a flaw“. In reality, only after location, evaluation and diagnosis has been made, can it be determined whether or not there is a flaw which effects the purpose of the 5test object. The term “discontinuity“ is therefore always us
25、ed as long as it is not certain whether it concerns a flaw which means a non-permissible irregularity.(不规则 )代替使用 “反射体 ”这个词，超声波操作员 经常使用的术语是 “ 断裂 “ 。这被定义为测试物体的不规律，判断测物体中是否存在裂纹。事实上，只有在定位后，才会进行评估和诊断，判定测试物体是否有影响其使用目的的裂纹存在。3. Detection of discontinuities断裂的寻找 The essential “tool“ for the ultrasonic operat
26、or is the probe, Figs. 1a + 1b.操作者的重要工具是探头， 图片 1a + 1b.Fig. 1a Straight-beam probe (section)图片 1a平行光束探头（ 切面 ）Housing 外壳 socket 插口 damping block 电阻块 matching element 匹配元件 crystal 晶体 protecting face(probe delay) 保护面（探头延迟）Fig. 1b Angle-beam probe (section)图片 1b斜探头 （ 切面 ）perspex wedge (probe delay) 塑胶楔（
27、探头延迟）The piezo electric element, excited by an extremely short electrical discharge, transmits an ultrasonic pulse. The same element on the other hand generates an electrical signal when it receives an ultrasonic signal thus causing it to oscillate. The probe is coupled to the surface of the test ob
28、ject with a liquid or coupling paste so that the sound waves from the probe are able to be transmitted into the test object.压电元件被非常短的电的释放刺激后,传输超声波脉冲。另一方面，当相同的元件接受到超声波信号时 ，会产生一个电波信号，引起它的振动。探头与测试物体表面间需要有液体或耦合剂，以便使来自探头的声波能够被传送到测试物体中。The operator then scans the test object, i.e. he moves the probe evenl
29、y to and fro across the surface. In doing this, he observes an instrument display for any signals caused by 6reflections from internal discontinuities, Fig. 2.接着操作者会对测试物体进行扫描。例如，在表面上平稳的移动探头。在这个过程中，操作者需要观察所有内部断裂引起的反射在仪器上的信号显示。图片2Fig. 2a Plane flaw straight-beam probe Fig. 2b Plane flaw angle-beam pro
30、be图片 2a平面裂纹 -平行光束探头 图片 2b平面裂纹 斜光束探头Every probe has a certain directivit y, i.e. the ultrasonic waves only cover a certain section of the test object. The area effective for the ultrasonic test is called the“sound beam“ which is characteristic for the applied probe and material in which sound waves p
31、ropagate.每个探头都具有一定的方向性，举例来说，超声波只能覆盖被测试物体的一部分。超声波测试有效的区域被称为 “声波束 ”。其特点是，当探头在材料上进行测试时，声波能够在材料中传播。A sound beam can be roughly divided into a convergent (focusing) area, the near- field, and a divergent (spreading) part, the far field, Fig. 3.一个声波束能够被粗略的划分为一个焦点区域（近场）和扩散区域(远场)。图片3Fig. 3 Sound field 图片3声场
32、N=近场长度 r =扩散角度 near field 近场 far field 远场acoustic axis 声轴 central beam 中心光束The length N of the near-field (near-field length) and the divergence angle is de- pendent 7on the diameter of the element, its frequency and the sound velocity of the material to be tested. The center beam is termed the acou
33、stic axis. The shape of the sound beam plays an important part in the selection of a probe for solving a test problem. It is often sufficient to draw the acoustic axis in order to show what the solution to a test task looks like. A volumetric discontinuity (hollow space, foreign material) reflects t
34、he sound waves in different directions, Figs. 4a + 4b.近场的长度和扩散的角度取决于元件的直径、频率和测试材料的音速。中心光速被称为声轴。在选择探头进行测试时，声波束的形状具有重要作用。为了能够显示出测试任务的解决方法，必须画出声轴。一个体积的断裂（中空，外来物质）会将声波反射到不同的方向。图片4a和4bFig. 4a Volumetric discontinuity Fig. 4b Volumetric discontinuity straight-beam probe angle-beam probe图片 4a 断裂体积的测定 平行光束探
35、头 图片 4b断裂体积的测定 角度探头 The portion of sound wave which comes back to the probe after being reflected by the discontinuity is mainly dependent on the direction of the sound wave; i.e. it does not matter whether scanning is made with a straight-beam probe or an angle-beam probe or whether it is carried o
36、ut from different surfaces on the test object, Fig. 5.声波被断裂反射后，一部分的声波会返回到探头。举例来说，无论是平行光束或角度探头进行的扫描，或者对表面不同的测试物体进行的扫描。图片5Fig. 5 Volumetric flaw detection form different directions图片 5 裂纹体积的测定 从不同的方向进行探测If the received portion of the reflected sound wave from the probe is sufficient then the detection
37、 of the existing volumetric discontinuity is not critical, this 8means that the operator is able to detect it by scanning from different directions. A plane (two-dimensional) discontinuity (e.g. material separation, crack) reflects the ultrasonic waves mostly in a certain direction, Fig. 6.如果探头发射后，被
38、反射的 声 波中被接收的部分是充足的，那就会很容易 探测到物体上存在的断裂，这就意味着操作者能够通过对不同方位的 扫描发现断裂。一个平面（两维的）的断裂（举例来说，材料的隔断，裂纹）反射出 的 超声波大多朝一个方向。图片 6Fig. 6 Reflection on angled plane discontinuity图片 6 具有角度的平面断裂上的反射If the reflected portion of the sound wave is not received by the probe then it is unlikely that the discontinuity will be
39、detected. The possibilities of detection only increase when the plane discontinuity is hit vertically by the sound beam. This applies to discontinuities which are isolated within the test object.如果声波的被反射的部分没有被探头接收到的 , 那么它就不太可能发现断裂。只有在音波束垂直击中平面断裂时，发现的可能性才会增加。这适用于在测试物体里面的被隔离的断裂。With plane discontinuit
40、ies which are open to the surface of the test object, e.g. a crack running vertically from the surface into the test object, a vertical scan of the crack does not always produce the required success. In this case wave overlapping occurs(interferences) due to sound wave reflection on the side wall of
41、 the test object which seems as if the sound wave bends away from the corresponding side wall, Fig. 7.开放于表面的平面断裂，举例来说，一个垂直于表面进入到测试物体中的裂纹，裂纹的垂直扫描不一定会成功。在这情况是由于声波反射到测试物体的一边的墙，看起来声波似乎偏离了另一面墙，导致波的重叠。图片7。裂纹9Fig. 7 Apparent deformation of the sound beam on a side wall图片 7. 在一面壁上的声波光束的明显变形In such cases, th
42、e probability of crack detection is very good if the angle reflection effect is used, Fig. 8a. At the 90 edge, between the crack and the surface of the test object, the sound waves are reflected back within themselves due to a double reflection, Fig. 8b.在一些例子中，如果使用反射角度，会容易发现到裂纹。图片8a。在90度角的边缘，在裂纹和测试物
43、体表面之间，由于一个双重的反射，声波会被反射到自身中。图片8b Fig. 8a Crack detection with 45 scanning Fig. 8b Angle reflection effect图片 8a以45度角进行扫描探测裂纹 图片 8b 角度反射效果Use of the angle reflection effect is often even possible when a plane discontinui ty, which is vertical to the surface, does not extend to the surface and under the
44、 condition that the sound wave reflections at the discontinuity and the surface are received by the probe, Fig. 9.当平面断裂垂直于表面，还没有延伸到表面时，会经常采取角度反射，表面和断裂反射的声波会被探头接收。图片9Fig. 9 Plane, vertical reflector near the surface图片9 接近于表面的垂直的平面反射体Often in thick-walled test objects, in which there are vertical disc
45、ontinuities, this con- dition cannot be fulfilled so that the reflected sound waves from the discontinuity and the surface of the test object do not return to the probe. In this case, a second probe is used for receiving the reflected portions of sound thus enabling detection of the discontinui ty.在
46、较厚的被测试物体中检测垂直断裂,这情况不易能够被发现，因为，被断裂和测试物体表面反射的声波不能返回到探头。 在这情况下，需要使用第二个探头接收反射的声波，通过另一边那个探头发现断裂。With this type of testing, the Tandem Technique, one probe is used as a transmitter, and the other probe is used as the receiver. Both probes are moved over the surface of the test object and are spaced apart
47、at a fixed distance. Scanning is made for 10vertically positioned discontinuities at different depths of the test object, depending on the probe spacing, Figs. 10a, 10b and 10c.在使用双探头的检测技术中，用一个探头作为传送器，另一个探头作为接收器。在测试物体的表面上移动两个探头，而且以固定的距离隔开两个探头。扫描测试物体不同深度上的垂直断裂，取决于探头的间隔距离。图片10a,10b,10cFig. 10a Angle reflection effect图片 10a 角度反射效果Fig. 10b Tandem testing: center zone Fig. 10c Tamden testing: lower zone图片10b
