Gandhinagar Institute of Technology(012)

MATERIAL SCIENCE AND METALLURGYALA ON

“NON DESTRUCTIVE TESTING”

Branch : Mechanical Prepared by:VIDISHA VYAS(140120119253) / ME /3A1HIMANSHI GUPTA(140120119057) / ME /3A1PRACHI SHARMA(140120119216)/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

NON DESTRUCTIVE TEST DESTRUCTIVE TESTUsed 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 ExpensiveLess skill Skill is requirede.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 fluxleakage 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