Gandhinagar Institute of Technology(012) MATERIAL SCIENCE AND METALLURGY ALA ON “NON DESTRUCTIVE TESTING” Branch : Mechanical Prepared by: HIMANSHI GUPTA(140120119057) / ME /3A1 Guided By: Prof. Jyotin Kateshia

NDT

NON-DESTRUCTIVE TESTING Non destructive testing(NDT) is one of the important methods used for evolution and quality control of metal components During testing, the metal component does not get damaged These tests are used to locate or find out the defects or flaws in the component

ADVANTAGES OF NDT The equipments are easy to handle Defects can be detected without damaging the components Methods are quick and accurate Components can be sorted out on the basis of electrical, magnetic or chemical properties Test results and other information can be conveniently recorded on paper films, cassettes and floppies

DIFFERENCE BETWEEN DESTRUCTIVE AND NON DESTRUCTIVE TEST Used for finding out defects of materials Used for finding out the properties of the material Load is not applied on the material Load is applied on the material No load applications, so no chance for material damage Due to load application, material gets damaged No requirement of special equipments Special equipments are required Non expensive Expensive Less skill Skill is required e.g: dye penetrate test, ultrasonic, radiography, etc e.g: tensile test, compression test, hardness test, etc

BASIC ELEMENTS OF NDT METHOD SOURCE MODIFICATION DETECTION INDICATION INTERPRETATION

METHODS OF NDT Dye Penetrant Testing (DPT) Magnetic Particle Testing (MPT) Ultrasonic Testing (UT) Eddy Current Testing (ECT) Radiography Testing (RT)

DYE PENETRANT TEST Used for detect the surface cracks or defects One of the most widely used NDT methods Used to inspect almost any material provided that its surface is not extremely rough It is used for surface detection of forging, casting, weld elements

PROCESS FOR DPT CLEANING DRYING OF SURFACE APPLICATION OF PENETRATE REMOVAL OF EXCESS OF PENETRATE APPLICATION OF DEVELOPER

ADVANTAGES OF DPT This method has high sensitivity to small surface discontinuities. Large areas and large volumes of parts/materials can be inspected rapidly and at low cost Indications are produced directly on the surface of the part and constitute a visual representation of the flaw Aerosol spray can make penetrant materials very portable Penetrant materials and associated equipments are relatively in expensive.

LIMITATIONS OF DPT Only surface breaking defects can be detected The inspector must have direct access to the surface being inspected Surface finish and roughness can affect inspection sensitivity Post cleaning of acceptable parts or materials is required Chemical handling and proper disposal is required.

MAGNETIC PARTICLE TESTING This method is suitable for the detection of surface and near surface discontinuities in magnetic material , mainly ferrite steel and iron METHODS OF MPT Dry method Wet method

PRINCIPLE OF MPT In the first figure the magnetized metal has no crack and there only two poles that is north pole and south pole. And in second figure the magnetized metal has a crack and at the crack point there creates another north and south pole for the magnetic flux leakage.

MPT IN GAS PIPE WELDING Particles make a cluster at the welding joint for magnetic flux leakage because of welding defects.

ADVANTAGES OF MPT Principally and relatively simple method Economical and easy to perform Portable for field testing Fast for production testing Reveal or disclose small surface flaws or cracks which may be tight

LIMITATIONS OF MPT Material must be ferromagnetic Orientation and strength of magnetic field is critical Detects surface and near-to-surface discontinuities only Large currents are required

ULTRASONIC TESTING A typical UT system consists of several functional units, such as the pulser/receiver, piezoelectric transducer, and display devices. A pulser/receiver is an electronic device that can produce high voltage electrical pulses. Driven by the pulser, the transducer generates high frequency ultrasonic energy. The sound energy is introduced and propagates through the materials in the form of waves. When there is a discontinuity (such as a crack) in the wave path, part of the energy will be reflected back from the flaw surface. The reflected wave signal is transformed into an electrical signal by the piezo electrical transducer and is displayed on a screen.

PULSE-ECHO METHOD

TRANSMISSION METHOD

ADVANTAGES OF ULTRASONIC TESTING Thickness and lengths up to 30 ft can be tested Position, size and type of defect can be determined Instant test results Portable Capable of being fully automated Access to only one side necessary

LIMITATIONS OF ULTRASONIC TESTING The operator can decide whether the test piece is defective or not while the test is in progress. Considerable degree of skill necessary to obtain the fullest information from the test. Very thin sections can prove difficult.

ULTRASONIC MEASUREMENT

EDDY CURRENT TESTING(ECT) Used to detect surface flaws, to measure thin walls from one surface only To measure thin coating sand in some applications to measure depth. This method is applicable to electrically conductive materials only In this method eddy currents are produced in the product by bringing it close to an alternating current carrying coil. The main applications of the eddy current technique are for the detection of surface or subsurface flaws, conductivity measurement and coating thickness measurement.

APPLICATION OF ECT Crack Detection Corrosion Monitoring Material Thickness Measurements Coating Thickness Measurements Conductivity Measurements

ADVANTAGES OF ECT Sensitive to small cracks and other defects Detect surface and near surface defects Inspection gives immediate results Equipment is very portable Method can be used for much more than flaw detection Inspects complex shapes and sizes of conductive materials

LIMITATIONS OF ECT Only conductive materials can be inspected Skill and training required is more extensive than other techniques Surface finish and roughness may interfere Depth of penetration is limited.

RADIOGRAPHY Radiography Testing (RT), or industrial radiography is NDT method of inspecting materials for hidden flaws by using the ability of short wavelength electromagnetic radiation (high energy photons)to penetrate various materials Radiographic Testing Method is nothing but to take the shadow picture of an object onto a film by the passage of X-ray or Gamma ray through it It is the same as the medical radiography (X-ray). Only difference in their wave length.

RADIOGRAPHY TESTING PROCESS

DIFFERENCE BETWEEN X RAY AND GAMMA RAY RADIOGRAPHY X RAYS GAMMA RAYS Larger wavelength Shorter wavelength Less penetration power High penetration power Used for components having thickness up to 62mm Used for more thickness components Only one component can be examined at a time Many components can be examined at a time Equipment is larger in size Equipment is smaller in size More intensity and faster Less intensity and slower

RADIOGRAPHY

LIMITATIONS OF RADIOGRAPHY Possible health hazard Need to direct the beam accurately for two-dimensional defects Film processing and viewing facilities are necessary Not suitable for automation Not suitable for surface defects.

APPLICATION OF RADIOGRAPHY For detection of internal defects For detection of porosity, casting, lack of fusion in welding, cracks For measurement of geometry variation and thickness of components

RADIOGRAPHY

ULTRASONIC TESTING RADIOGRAPHY TESTING Less flaw detection capabilities More flaw detection capabilities Compared to radiography less operational safety is required More operational safety is required as the radiations are harmful Probe is used Probe is not used Better accuracy and reliability Very fast method of testing Operated manually Less or no manual work Used for detection of internal defect, measurement of conductivity and crack depth For detection of internal defects, porosity, casting, lack of fusion in welding, cracks, measurement of geometry variation and thickness of components

Ultrasonic testing Radiography testing

CONCLUSION NDT is a new technology and system for industrial inspection and testing Many developed countries uses this technology because of its huge benefits Modern NDT methods will become just as an important tool for risk based inspection approaches and maintenance planning For this purpose every industry should have a NDT division with NDT personnel