Spot welding ppt on out motive body shopp

1. WELD
TESTING

2. DESTRUCTIVE
AND
NON-DESTRUCTIVE

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

4. 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

5. WORKSHOP TESTS
TENSILE BENDING
IMPACT HARDNES
FATIGUE CRACKING

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

7. TENSILE

8. BEND TESTING
 Shows
Physical condition of the weld
Determine welds efficiency
• Tensile strength
• Ductility
• Fusion and penetration

9. BEND TEST
 Bend through 180
O
 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.

10. Root bend

11. FACE BEND

13. 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 45
o
bevel or a “U” notch.

14. TEST MACHINE

16. CHARPY

17. IZOD

18. ANY QUESTIONS

19. HARDNESS TESTS.
 This gives the metals ability to show
resistance to indentation which show it’s
resistance to wear and abrasion.
 The tests are
 Brinell
 Rockwell
 Vickers diamond pyramid
 Scleroscope

20. VICKERS HARDNES

23. FATIGUE
 the testing of Material that is subject to fluctuating
loads
 HAIGH Electro magnetic tester.
 W’O’HLER Uses rotating chuck with weight

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

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

26. 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

27. 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.

28. 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 10-20%caustic
soda in water

29. HAVE YOU
ANY
QUESTIONS

30. NON-DESTRUCTIVE
TESTING

32. 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

33. DYE PENETRANTS
 These are an aid to visual inspection
 Will only find surface defects
 Use correct type

34. DYE PENETRANTS

35. DYE PENETRANTS
 Types
 Red
 Flouresant
 CAUTION
 Oil based
 Water washable

36. DETECTION

37. MAGNETIC PARTICLE
 Mainly for surface
defects
 Some sub surface
defects can be found
 Only ferrous metal

38. ACOUSTICS
Striking with a rounded
object
Ringing tone if no defect
Tone changes when
object is cracked

39. 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.

41. PRESSURE TEST

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

43. X- RAY

46. 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

47. 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

48. ULTRA SONIC

51. THIS IS THE END OF THE
LESSON
ARE THERE ANY
QUESTIONS