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Shielded Metal Arc Welding DEFECTS PPT Lesson 2
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- 2. What are Defectsin Welding? It is common in any type of manufacturing, there can be deviations in the shape and size of the metal structure.
- 3. Different Types OfWelding Defects Porosity • It is a welding defect that results from unwanted gasses being trapped within the molten weld puddle during solidification.
- 4. CAUSES • Contaminated weldingelectrode • Long arc length • High voltage of welding machine
- 5. Remedies •Use appropriate electrodefor the job. •Maintain correct arc length. •Use proper current of a voltage.
- 6. Four Classification ofWelding Porosity 1. Scattered Porosity • Occurs where several pores of different sizes are distributed irregularly in the volume of the weld metal.
- 7. Four Classification ofWelding Porosity 2. Clustered Porosity • It is a localized grouping of pores that may result from the initiation or termination of the welding arc.
- 8. Four Classification ofWelding Porosity 3. Linear Porosity • It occurs throughout the length of a weld and the voids are in a line with respect to the axis of the weld.
- 9. Four Classification ofWelding Porosity 4. Elongated Porosity • A form of porosity having a length greater than its width that lies approximately parallel to the weld axis.
- 10. Slag Inclusions • Itis common welding defect that occurs when slag, a welding by- product, gets stuck inside the weldment. Different Types Of Welding Defects
- 11. Causes •Improper maintenance ofthe metal. •Insoluble flux due to defective welding electrode. •Improper welding angle and travel rate of welding rod.
- 12. Remedies •Make sure thatthe metal that we used has a proper maintenance. •Use accurate welding electrode to avoid any casualties. •Have a proper electrode angle travel •rate
- 13. Incomplete Fusion • Isa planar weld discontinuity in which fusion does not occur between the weld metal and base metal or between and joining weld beads.
- 14. Causes • Improper manipulationof welding electrode. • Narrow welding groove. Remedies •Use accurate speed in manipulation of welding electrode. •Adjust welding groove.
- 15. Poor Penetration • Itis a joint root condition in a groove weld in which weld metal does not extend through the joint thickness.
- 16. Causes •To fast speedof welding process •Too large electrode •Too low current
- 17. Remedies •Avoid so muchspeed when working in a welding process. •Select size of electrode according to groove size. •Use enough current to obtain penetration and weld slowly.
- 18. Under Cut • Theweld reduces the cross-sectional thickness of the base metal.
- 19. Causes •Arc voltage isvery high. •Using large electrode is also not advisable. Remedies •Reduce the arc length or lower the voltage. •The diameter of the electrode should be small.
- 20. Under Fill • Itis the failure of the welding operator to fill the joint with weld metal.
- 21. Causes •The welder mustbe inexperienced. Remedies •Enhance welding knowledge and experience.
- 22. Overlap • Overlap occursdue to the overflow of weld metal on the surface of base metal.
- 23. Causes •High welding current •Useof large electrode Remedies •Lest welding current •Use smaller electrode
- 24. Crack of Weld •Occurs in weld metal and based metal when localized stresses exceed ultimate strength of the metal.
- 25. Two types ofCrack Weld Hot Cracks • Hot cracks occur during welding or soon after the completion of welding process. Cold Cracks • Cold cracks occur after the solidification of weld metal.
- 26. Causes •Poor ductility ofthe given base metal •High concentration of residual stress Remedies •Using appropriate materials may decrease the change of crack. •Pre heating and Post heating to avoid rapid cooling.
- 27. Pre Heating • Occurswhen heat is applied to the metal prior to welding. Post Heating • Post heating in welding refers the heating of the weldment after weld completion.
- 28. Spatter • It isthe droplets of molten material during welding.
- 29. Causes • Too highcurrent • Too long arc Remedies •Adjust current properly •Adjust voltage
- 30. Identify these picturesbased on your understanding in our lesson Scattered Porosity
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- 34. Quiz Instructions: Give me the9 types of welding defects in any order.
- 35. Answer: 1. Porosity 2. SlagInclusion 3. Incomplete fusion 4. Poor penetration 5. Under Cut 6. Under Fill 7. Overlap 8. Crack of Weld 9. Spatter