Weld testing

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WELDTESTING
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DESTRUCTIVE AND
NON-DESTRUCTIVE
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DESTRUCTIVE TESTING

• These can be divided into two parts,
• Tests capable of being performed in the
  workshop.
• Laboratory tests.
• microscopic-macroscopic , chemical and corrosive.

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REASONS

• Defects occur during welding which affect the
  quality and hardness of the plate
• Other defects occur through lack of knowledge of
  and skill of the welder
• For the training of welders

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WORKSHOP TESTS

• TENSILE BENDING
• IMPACT HARDNES
• FATIGUE CRACKING

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TENSILE

• Material is sectioned and edges rounded of to
  prevent cracking.
• Punch marks are made to see elongation.

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TENSILE
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BEND TESTING

• Shows
• Physical condition of the weld
• Determine welds efficiency
• Tensile strength
• Ductility
• Fusion and penetration

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BEND TEST

• Bend through 180O
• the specimen should be a minimum of 30mm wide
• The fulcrums diameter is 3x thickness of the
  plate
• The bottom rollers have a distance of the
  diameter of the former 2.2 times the
  thickness of the plate
• Upper 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.

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Root bend
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FACE BEND
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ANY QUESTIONS
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IMPACT

• CHARPY AND IZOD
• Gives 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 notch
• 2mm depth at a 45obevel or a U notch.

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TEST MACHINE
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CHARPY
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IZOD
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ANY QUESTIONS
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HARDNESS TESTS.

• This gives the metals ability to show resistance
  to indentation which show its resistance to
  wear and abrasion.
• The tests are
• Brinell
• Rockwell
• Vickers diamond pyramid
• Scleroscope

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VICKERS HARDNES
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FATIGUE

• the testing of Material that is subject to
  fluctuating loads
• HAIGH Electro magnetic tester.
• WOHLER Uses rotating chuck with weight

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CRACKING

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

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CRACKING

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

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MICROSCOPIC

• Used to determine the actual structure of the
  weld and parent metal
• Up to 50,000 times magnification with an electron
  beam microscope
• Polishing must be of a very high standard

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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.

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ETCHING REAGENTS

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

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HAVE YOU ANY QUESTIONS
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• NON-DESTRUCTIVE
• TESTING
  
  

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VISUAL

• While welding
  
• The rate the electrode melts
• The way the weld metal flows
• Sound of the arc
• The light given of

• After welding
• Under cut
• Lack of root fusion
• Any pin holes from gas or slag
• Amount of spatter
• Dimensions of weld

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DYE PENETRANTS

• These are an aid to visual inspection
• Will only find surface defects
• Use correct type

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DYE PENETRANTS
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DYE PENETRANTS

• Types
• Red
• Flouresant
• CAUTION
• Oil based
• Water washable

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DETECTION
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MAGNETIC PARTICLE

• Mainly for surface defects
• Some sub surface defects can be found
• Only ferrous metal

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ACOUSTICS

• Striking with a rounded object
• Ringing tone if no defect
• Tone changes when object is cracked

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APPLICATION OF A LOAD

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

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PRESSURE TEST
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RADIOGRAPHIC

• X-RAY
• GAMMA RAY
• Electro magnetic radiation of short duration
• Both of these methods are a danger to health

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X- RAY
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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

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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

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ULTRA SONIC
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THIS IS THE END OF THE
LESSON

• ARE THERE ANY QUESTIONS