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1、无无损检测损检测概述概述第1页，共31页，编辑于2022年，星期六是无损检测的英文（是无损检测的英文（Non-destructive testing）缩写，是）缩写，是指对材料或工件实施一种不损害或不影响其未来使用性能或指对材料或工件实施一种不损害或不影响其未来使用性能或用途的检测手段。通过使用用途的检测手段。通过使用 NDT，能发现材料或工件内部和，能发现材料或工件内部和表面所存在的缺欠，能测量工件的几何特征和尺寸，能测定表面所存在的缺欠，能测量工件的几何特征和尺寸，能测定材料或工件的内部组成、结构、物理性能和状态等。材料或工件的内部组成、结构、物理性能和状态等。无损检测定义无损检测定义第2
2、页，共31页，编辑于2022年，星期六六大常规无损检测方法六大常规无损检测方法 目测目测 渗透探伤渗透探伤 磁粉探伤磁粉探伤 超声波探伤超声波探伤 涡流探伤涡流探伤 射线探伤射线探伤第3页，共31页，编辑于2022年，星期六Most basic and common inspection method.Tools include fiberscopes,borescopes,magnifying glasses and mirrors.目测检查目测检查第4页，共31页，编辑于2022年，星期六A liquid with high surface wetting characteristics
3、is applied to the surface of the part and allowed time to seep into surface breaking defects.The excess liquid is removed from the surface of the part.A developer(powder)is applied to pull the trapped penetrant out the defect and spread it on the surface where it can be seen.Visual inspection is the
4、 final step in the process.The penetrant used is often loaded with a fluorescent dye and the inspection is done under UV light to increase test sensitivity.渗透探伤渗透探伤第5页，共31页，编辑于2022年，星期六磁粉探伤磁粉探伤The part is magnetized.Finely milled iron particles coated with a dye pigment are then applied to the speci
5、men.These particles are attracted to magnetic flux leakage fields and will cluster to form an indication directly over the discontinuity.This indication can be visually detected under proper lighting conditions.第6页，共31页，编辑于2022年，星期六Magnetic Particle Crack Indications 第7页，共31页，编辑于2022年，星期六射线探伤射线探伤The
6、 radiation used in radiography testing is a higher energy(shorter wavelength)version of the electromagnetic waves that we see as visible light.The radiation can come from an X-ray generator or a radioactive source.High Electrical PotentialElectrons-+X-ray Generator or Radioactive Source Creates Radi
7、ationExposure Recording DeviceRadiation Penetrate the Sample第8页，共31页，编辑于2022年，星期六Film RadiographyTop view of developed film X-ray film底片：片基、乳剂层（底片：片基、乳剂层（AgBr）显影：显影剂有选择的和感过光的潜影部显影：显影剂有选择的和感过光的潜影部分作用，形成银颗粒分作用，形成银颗粒定影：将未显影的定影：将未显影的AgBr溶解去掉溶解去掉=more exposure=less exposure第9页，共31页，编辑于2022年，星期六Radiograph
8、ic Images第10页，共31页，编辑于2022年，星期六射线防护射线防护CC名称半衰期Co60 钴605.3年Cs137 铯13733年Ir192 铱19274天辐射剂量的控制方法：辐射剂量的控制方法：外照射防护的基本依据，即三大防护原则：外照射防护的基本依据，即三大防护原则：11、时间、时间要控制射线对人体的曝光时间；要控制射线对人体的曝光时间；22、距离、距离要控制射线源到人体间的距离；要控制射线源到人体间的距离；33、屏蔽、屏蔽在人体和射线源之间间隔一层吸收物质在人体和射线源之间间隔一层吸收物质。第11页，共31页，编辑于2022年，星期六Conductive materialCo
9、ilCoils magnetic fieldEddy currentsEddy currents magnetic field涡流探伤涡流探伤第12页，共31页，编辑于2022年，星期六Eddy Current TestingEddy current testing is particularly well suited for detecting surface cracks but can Eddy current testing is particularly well suited for detecting surface cracks but can also be used to
10、 make electrical conductivity and coating thickness measurements.also be used to make electrical conductivity and coating thickness measurements.Here a small surface probe is scanned over the part surface in an attempt to Here a small surface probe is scanned over the part surface in an attempt to d
11、etect a crack.detect a crack.第13页，共31页，编辑于2022年，星期六High frequency sound waves are introduced into a material and they are reflected back from surfaces or flaws.Reflected sound energy is displayed versus time,and inspector can visualize a cross section of the specimen showing the depth of features th
12、at reflect sound.fplatecrack0246810initial pulsecrack echoback surface echoOscilloscope,or flaw detector screen超声波探伤超声波探伤 第14页，共31页，编辑于2022年，星期六Ultrasonic ImagingGray scale image produced using the sound reflected from the front surface of the coinGray scale image produced using the sound reflected
13、from the back surface of the coin(inspected from“heads”side)High resolution images can be produced by plotting signal strength or time-of-flight using a computer-controlled scanning system.第15页，共31页，编辑于2022年，星期六Common Application of NDTInspection of Raw ProductsInspection Following Secondary Process
14、ingIn-Services Damage Inspection第16页，共31页，编辑于2022年，星期六Inspection of Raw ProductsForgings,Castings,Extrusions,etc.第17页，共31页，编辑于2022年，星期六MachiningWeldingGrindingHeat treatingPlatingetc.Inspection Following Secondary Processing第18页，共31页，编辑于2022年，星期六CrackingCorrosionErosion/WearHeat Damageetc.Inspection
15、 For In-Service Damage第19页，共31页，编辑于2022年，星期六Power Plant InspectionProbeSignals produced by various amounts of corrosion thinning.Periodically,power plants are shutdown for inspection.Inspectors feed eddy current probes into heat exchanger tubes to check for corrosion damage.Pipe with damage第20页，共31页
16、，编辑于2022年，星期六Wire Rope InspectionElectromagnetic devices and visual inspections are used to find broken wires and other damage to the wire rope that is used in chairlifts,cranes and other lifting devices.第21页，共31页，编辑于2022年，星期六Storage Tank InspectionRobotic crawlers use ultrasound to inspect the wall
17、s of large above ground tanks for signs of thinning due to corrosion.Cameras on long articulating arms are used to inspect underground storage tanks for damage.第22页，共31页，编辑于2022年，星期六Aircraft InspectionNondestructive testing is used extensively during the manufacturing of aircraft.NDT is also used to
18、 find cracks and corrosion damage during operation of the aircraft.A fatigue crack that started at the site of a lightning strike is shown below.第23页，共31页，编辑于2022年，星期六Jet Engine InspectionAircraft engines are overhauled after being in service for a period of time.They are completely disassembled,cle
19、aned,inspected and then reassembled.Fluorescent penetrant inspection is used to check many of the parts for cracking.第24页，共31页，编辑于2022年，星期六Sioux City,Iowa,July 19,1989A defect that went undetected in an engine disk was responsible for the crash of United Flight 232.Crash of United Flight 232第25页，共31
20、页，编辑于2022年，星期六Pressure Vessel InspectionThe failure of a pressure vessel can result in the rapid release of a large amount of energy.To protect against this dangerous event,the tanks are inspected using radiography and ultrasonic testing.第26页，共31页，编辑于2022年，星期六Rail InspectionSpecial cars are used to
21、inspect thousands of miles of rail to find cracks that could lead to a derailment.第27页，共31页，编辑于2022年，星期六Bridge InspectionThe US has 578,000 highway bridges.Corrosion,cracking and other damage can all affect a bridges performance.The collapse of the Silver Bridge in 1967 resulted in loss of 47 lives.
22、Bridges get a visual inspection about every 2 years.Some bridges are fitted with acoustic emission sensors that“listen”for sounds of cracks growing.第28页，共31页，编辑于2022年，星期六NDT is used to inspect pipelines to prevent leaks that could damage the environment.Visual inspection,radiography and electromagne
23、tic testing are some of the NDT methods used.Remote visual inspection using a robotic crawler.Radiography of weld joints.Magnetic flux leakage inspection.This device,known as a pig,is placed in the pipeline and collects data on the condition of the pipe as it is pushed along by whatever is being tra
24、nsported.Pipeline Inspection第29页，共31页，编辑于2022年，星期六Special MeasurementsBoeing employees in Philadelphia were given the privilege of evaluating the Liberty Bell for damage using NDT techniques.Eddy current methods were used to measure the electrical conductivity of the Bells bronze casing at various p
25、oints to evaluate its uniformity.第30页，共31页，编辑于2022年，星期六For More Information on NDT在不损伤被测材料的情况下，检查材料的内在或表面缺陷，或测定材料的某些物理量、性能、组织状在不损伤被测材料的情况下，检查材料的内在或表面缺陷，或测定材料的某些物理量、性能、组织状态等的检测技术。广泛用于金属材料、非金属材料、复合材料及其制品以及一些电子元器件的检测。态等的检测技术。广泛用于金属材料、非金属材料、复合材料及其制品以及一些电子元器件的检测。常用的无损检测技术有：常用的无损检测技术有：射线探伤。利用射线探伤。利用XX射线或射
26、线或射线在穿透被检物各部分时强度衰减的不同，射线在穿透被检物各部分时强度衰减的不同，检测被检物的缺陷。若将受到不同程度吸收的射线投射到检测被检物的缺陷。若将受到不同程度吸收的射线投射到XX射线胶片上射线胶片上 ，经显影后可得到显示物，经显影后可得到显示物体厚度变化和内部缺陷情况的照片。如用荧光屏代替胶片，可直接观察被检物体的内部情况。体厚度变化和内部缺陷情况的照片。如用荧光屏代替胶片，可直接观察被检物体的内部情况。超声检测。利用物体自身或缺陷的声学特性对超声波传播的影响，来检测物体的缺陷或某些超声检测。利用物体自身或缺陷的声学特性对超声波传播的影响，来检测物体的缺陷或某些物理特性。在超声检测中
27、常用的超声频率为物理特性。在超声检测中常用的超声频率为0.50.555兆赫（兆赫（MHzMHz）。最常用的超声检测是脉冲探伤。）。最常用的超声检测是脉冲探伤。声发射检测。通过接收和分析材料的声发射信号来评定材料的性能或结构完整性。材料中因声发射检测。通过接收和分析材料的声发射信号来评定材料的性能或结构完整性。材料中因裂缝扩展、塑性变形或相变等引起应变能快速释放而产生应力波的现象称为声发射。材料在外裂缝扩展、塑性变形或相变等引起应变能快速释放而产生应力波的现象称为声发射。材料在外部因素作用下产生的声发射，被声传感器接收转换成电信号，经放大后送至信号处理器，从而部因素作用下产生的声发射，被声传感器
28、接收转换成电信号，经放大后送至信号处理器，从而测量出声发射信号的各种特征参数。测量出声发射信号的各种特征参数。渗透探伤。利用某些液体对狭窄缝隙的渗透性来探测表渗透探伤。利用某些液体对狭窄缝隙的渗透性来探测表面缺陷。常用的渗透液为含有有色染料或荧光的液体。面缺陷。常用的渗透液为含有有色染料或荧光的液体。磁粉探伤。通过磁粉在物体缺陷附近磁粉探伤。通过磁粉在物体缺陷附近漏磁场中的堆积来检测物体表面或近表面处的缺陷，被检测物体必须具有铁磁性。此外，中子漏磁场中的堆积来检测物体表面或近表面处的缺陷，被检测物体必须具有铁磁性。此外，中子射线照相法、激光全息照相法、超声全息照相法、红外检测、微波检测等无损检测新技术也得射线照相法、激光全息照相法、超声全息照相法、红外检测、微波检测等无损检测新技术也得到了发展和应用。到了发展和应用。第31页，共31页，编辑于2022年，星期六