WELDWELDTESTINGTESTING

DESTRUCTIVE AND

NON-DESTRUCTIVE

DESTRUCTIVE TESTING These can be

divided into two parts,Tests capable of

being performed in the workshop.Laboratory tests.

microscopic-macroscopic , chemical and corrosive.

REASONS

Defects occur during welding which affect the quality and hardness of the plateOther defects occur through lack of knowledge of and skill of the welderFor the training of welders

WORKSHOP TESTS

TENSILE BENDING

IMPACT HARDNES

FATIGUE CRACKING

TENSILE

Material is sectioned and edges rounded of to prevent cracking.

Punch marks are made to see elongation.

TENSILE BEND TESTING

ShowsPhysical condition of the weldDetermine welds efficiency

• Tensile strength• Ductility• Fusion and penetration

BEND TEST

Bend through 180O

the specimen should be a minimum of 30mm wideThe fulcrums diameter is 3x thickness of the plateThe bottom rollers have a distance of the diameter of the former + 2.2 times the thickness of the plateUpper and lower surfaces ground or filed flat and edges rounded off.the tests should be one against the root -another against the face ,and in some cases a side bend.

Root bend

FACE BEND

IMPACT

CHARPY AND IZODGives the toughness and shock loading of the material and weld at varying temperatures with a notch such as under cut The measurement is the energy required to to break a specimen with a given notch2mm depth at a 45

obevel or a “U” notch.

TEST MACHINE

CHARPY

IZODANY QUESTIONS

HARDNESS TESTS.

This gives the metals ability to show resistance to indentation which show it’s resistance to wear and abrasion.The tests are

BrinellRockwellVickers diamond pyramidScleroscope

VICKERS HARDNES

FATIGUE

the testing of Material that is subject to fluctuating loadsHAIGH Electro magnetic tester.W’O’HLER Uses rotating chuck with weight

CRACKING

REEVES Test study the hardening and cracking of welds.The compatibility of electrodes for the metal being joined.

CRACKING

Three Sides Are Welded With Known Compatible Electrodes.The front edge is welded with the test electrode.if incompatible it will crack.

MICROSCOPIC

Used to determine the actual structure of the weld and parent metalUp to 50,000 times magnification with an electron beam microscopePolishing must be of a very high standard

MACROSCOPIC

Examined using a magnifying glass .magnification from 2 to 20 time.it will show up slag entrapment or cracks .polishing not as high as micro.

ETCHING REAGENTS

These are acids used to show up different structures in metalsFor steels the most common is “1-2 % nitric acid in distilled water or alcohol.Aluminum uses a solution of 10-20%caustic soda in water

HAVE YOU ANY

QUESTIONS NON-DESTRUCTIVE TESTING

VISUAL

While welding The rate the electrode meltsThe way the weld metal flowsSound of the arcThe light given of

After weldingUnder cut Lack of root fusionAny pin holes from gas or slagAmount of spatterDimensions of weld

DYE PENETRANTS

These are an aid to visual inspection

Will only find surface defects

Use correct type

DYE PENETRANTS

DYE PENETRANTS

TypesRed Flouresant

CAUTIONOil basedWater washable

DETECTION

MAGNETIC PARTICLE

Mainly for surface defectsSome sub surface defects can be foundOnly ferrous metal

ACOUSTICS

Striking with a rounded object

Ringing tone if no defect

Tone changes when object is cracked

APPLICATION OF A LOAD

Used to test pressure vesselsPipe lines The item for testing is filled with water or oil it is then pressurised using a pumpA safety valve is set 1.5 to 2 times below the working pressure.

PRESSURE TESTRADIOGRAPHIC

X-RAYGAMMA RAYElectro magnetic

radiation of short duration

Both of these methods are a danger to health

X- RAY

X-RAY VIEWER

Pictures taken are viewed as negatives

will only give flat image not in three dimensional

darkened area must be used for viewing

ULTRASONIC TESTING

This uses high pitched sound

The sound will not pass through an air gap so bounces back and is picked up on a receiver

The reader is a oscilloscope

ULTRA SONIC

THIS IS THE END OF THE LESSON

ARE THERE ANY QUESTIONS