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

2. NDT

3. 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

4. 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

5. 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

6. BASIC ELEMENTS OF NDT METHOD
SOURCE
MODIFICATION
DETECTION
INDICATION
INTERPRETATION

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

8. 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

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

11. 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.

12. 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.

13. 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

14. 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.

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

16. 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

17. 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

18. 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.

19. PULSE-ECHO METHOD

20. TRANSMISSION METHOD

21. 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

22. 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.

23. ULTRASONIC MEASUREMENT

24. 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.

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

26. 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

27. 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.

28. 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.

29. RADIOGRAPHY TESTING PROCESS

30. 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

31. RADIOGRAPHY

32. 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.

33. 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

34. RADIOGRAPHY

35. 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

36. Ultrasonic testing
Radiography testing

37. 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