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GB/T 20737—2006/ISO/TS 18173:2005《无损检测 通用术语和定义》1 范围
本标准界定了在无损检测专业中广泛使用的通用技术术语。
2 术语和定义
2.1
合格质量水平 acceptable quality level
在抽样检测中，按平均方式处理而被认为是符合要求的有缺陷的最大百分数或每百个单元中有缺陷单元的最大数。
2.2
验收准则 acceptance criteria
为确定被检试样的可验收性所依据的准则。
2.3
验收水平 acceptance level
验收等级
为了验收或拒收，将一组规定参数设定为门槛。
2.4
人工不连续 artificial discontinuity
用机械或其他方法加工到材料块上的诸如孔或槽口等不连续。
2.5
仪器校准 calibration, instrument
用已知参考物比较仪器或调节仪器。
2.6
缺陷 defect
尺寸、形状、取向、位置或性质不满足规定的验收准则而拒收的一个或多个伤。
2.7
检测灵敏度 detection sensitivity
一种 NDT 技术检测不连续的能力。
注： 较高的检测灵敏度，具有较强的检测微小不连续的能力（见检测门槛）。
2.8
检测门槛 detection threshold
检测阈值
检测所能够显示的最低界限。
2.9
不连续 discontinuity
连续或结合的缺失；材料或工件在物理结构或形状上有意或无意的中断。
2.10
伪显示 false indication
假显示
被解释成是由不连续或缺欠之外的其他状况所引起的信号或表现，其形式随所用的 NDT 方法而变化。
2.11
伤 flaw
损伤
用 NDT 可检测到的，但不一定是拒收的缺欠或不连续。
2.12
伤特性化 flaw characterization
伤表征
基于 NDT 响应，对伤用尺寸、形状、取向、位置、形成或其他特征来表示的过程。
2.13
缺欠 imperfection
质量特性与预期状况的偏离。
2.14
显示 indication
不连续的信号或表现，其形式随所用的 NDT 方法而变化。
2.15
解释 interpretation
确定是否是相关显示、非相关显示或伪显示。
2.16
噪声 noise
不想要的信号或响应，它们会干扰对想要的信号或响应的接收、解释或处理。
2.17
无损评价 non-destructive evaluation
无损检测
见无损检测（2.20）。
2.18
无损检查 non-destructive examination
无损检测
无损检验
见无损检测（2.20）。
2.19
无损检验 non-destructive inspection
无损检测
无损探伤
见无损检测（2.20）。
2.20
无损检测 non-destructive testing
NDT
以不损害预期实用性和可用性的方式来检查材料或零部件的技术方法的开发和应用，其目的是为了：探测、定位、测量和评定伤；评价完整性、性质和构成；测量几何特性。
2.21
非相关显示 nonrelevant indication
由非拒收的不连续类型或状况所引起的 NDT 显示.。
注： 伪显示是非相关显示。
2.22
参考试块 reference block
具有规定的冶金、几何形状和尺寸特性的材料块，用来校准和评价设备。
注： 可含有一个或多个人工不连续。
2.23
参考试件 reference test piece
含有已知不连续的材料块，用来设置或校验设备和（或）过程的灵敏度。
2.24
相关显示 relevant indication
需要评定的由不连续类型或状况引起的 NDT 显示。
2.25
分辨力 resolution
有效辨别两个紧密相邻不连续的能力。
2.26
定量 sizing
确定需评定的不连续或显示的尺寸。
2.27
观察 viewing
为了确定显示的存在或不存在，对作为 NDT 结果的数据或迹象等进行系统的审视。
2.28
观察条件 viewing conditions
观察过程中周围环境条件的描述。
What's NDT The field of Nondestructive Testing (NDT) is a very broad, interdisciplinary field that plays a critical role in assuring that structural components and systems perform their function in a reliable and cost effective fashion. NDT technicians and engineers define and implement tests that locate and characterize material conditions and flaws that might otherwise cause planes to crash, reactors to fail, trains to derail, pipelines to burst, and a variety of less visible, but equally troubling events. These tests are performed in a manner that does not affect the future usefulness of the object or material. In other words, NDT allows parts and material to be inspected and measured without damaging them. Because it allows inspection without interfering with a product's final use, NDT provides an excellent balance between quality control and cost-effectiveness. Generally speaking, NDT applies to industrial inspections. Technology that is used in NDT is similar to those used in the medical industry; yet, typically nonliving objects are the subjects of the inspections.
What is NDE? Nondestructive evaluation (NDE) is a term that is often used interchangeably with NDT. However, technically, NDE is used to describe measurements that are more quantitative in nature. For example, an NDE method would not only locate a defect, but it would also be used to measure something about that defect such as its size, shape, and orientation. NDE may be used to determine material properties, such as fracture toughness, formability, and other physical characteristics. Some NDT/NDE Technologies: Many people are already familiar with some of the technologies that are used in NDT and NDE from their uses in the medical industry. Most people have also had an X-ray taken and many mothers have had ultrasound used by doctors to give their baby a checkup while still in the womb. X-rays and ultrasound are only a few of the technologies used in the field of NDT/NDE. The number of inspection methods seems to grow daily, but a quick summary of the most commonly used methods is provided below. Visual and Optical Testing (VT) The most basic NDT method is visual examination. Visual examiners follow procedures that range from simply looking at a part to see if surface imperfections are visible, to using computer controlled camera systems to automatically recognize and measure features of a component.
Radiography (RT) RT involves the use of penetrating gamma- or X-radiation to examine material's and product's defects and internal features. An X-ray machine or radioactive isotope is used as a source of radiation. Radiation is directed through a part and onto film or other media. The resulting shadowgraph shows the internal features and soundness of the part. Material thickness and density changes are indicated as lighter or darker areas on the film. The darker areas in the radiograph below represent internal voids in the component.
Magnetic Particle Testing (MT) This NDT method is accomplished by inducing a magnetic field in a ferromagnetic material and then dusting the surface with iron particles (either dry or suspended in liquid). Surface and near-surface flaws produce magnetic poles or distort the magnetic field in such a way that the iron particles are attracted and concentrated. This produces a visible indication of defect on the surface of the material. The images below demonstrate a component before and after inspection using dry magnetic particles.
Ultrasonic Testing (UT) In ultrasonic testing, high-frequency sound waves are transmitted into a material to detect imperfections or to locate changes in material properties. The most commonly used ultrasonic testing technique is pulse echo, whereby sound is introduced into a test object and reflections (echoes) from internal imperfections or the part's geometrical surfaces are returned to a receiver . Below is an example of shear wave weld inspection. Notice the indication extending to the upper limits of the screen. This indication is produced by sound reflected from a defect within the weld.
Penetrant Testing (PT) The test object is coated with a solution that contains a visible or fluorescent dye. Excess solution is then removed from the surface of the object but leaving it in surface breaking defects. A developer is then applied to draw the penetrant out of the defects. With fluorescent dyes, ultraviolet light is used to make the bleedout fluoresce brightly, thus allowing imperfections to be readily seen . With visible dyes, vivid color contrasts between the penetrant and developer make "bleedout" easy to see. The red indications below represent a number of defects in this component.
Electromagnetic Testing (ET) Electrical currents (eddy currents) are generated in a conductive material by a changing magnetic field. The strength of these eddy currents can be measured. Material defects cause interruptions in the flow of the eddy currents which alert the inspector to the presence of a defect. Eddy currents are also affected by the electrical conductivity and magnetic permeability of a material, which makes it possible to sort some materials based on these properties. The technician below is inspecting an aircraft wing for defects. Leak Testing (LT) Several techniques are used to detect and locate leaks in pressure containment parts, pressure vessels, and structures. Leaks can be detected by using electronic listening devices, pressure gauge measurements, liquid and gas penetrant techniques, and/or a simple soap-bubble test.
Acoustic Emission Testing (AE) When a solid material is stressed, imperfections within the material emit short bursts of acoustic energy called "emissions." As in ultrasonic testing, acoustic emissions can be detected by special receivers. Emission sources can be evaluated through the study of their intensity and arrival time to collect information about the sources of the energy, such as their location. |
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