Defects and Discontinuities
Download

Defects and Discontinuities

Advertisement
Download Presentation
Comments
johana
From:
|  
(4290) |   (0) |   (0)
Views: 160 | Added: 10-01-2012
Rate Presentation: 3 0
Description:
Defect. A flaw or flaws that by nature or accumulated effect render a part or product unable to meet minimum applicable acceptance standards or specifications. The term designates rejectability.. Discontinuity. An interruption of the typical structure of a material, such as a lack of homogeneity in its mechanical, metallurgical, or physical characteristics. A discontinuity is not necessarily a defect..
Defects and Discontinuities

An Image/Link below is provided (as is) to

Download Policy: Content on the Website is provided to you AS IS for your information and personal use only and may not be sold or licensed nor shared on other sites. SlideServe reserves the right to change this policy at anytime. While downloading, If for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.











- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -




1. Defects and Discontinuities

2. Defect A flaw or flaws that by nature or accumulated effect render a part or product unable to meet minimum applicable acceptance standards or specifications. The term designates rejectability.

3. Discontinuity An interruption of the typical structure of a material, such as a lack of homogeneity in its mechanical, metallurgical, or physical characteristics. A discontinuity is not necessarily a defect.

4. Weld Joint Discontinuities Inclusions Slag Wagontracks Tungsten Spatter Arc Craters Cracks Longitudinal Transverse Crater Throat Toe Root Underbead and Heat-affected zone Hot Cold or delayed

5. Misalignment (hi-lo) Definition: Amount a joint is out of alignment at the root

6. Undercut

7. Undercut (cont......) Undercut typically has an allowable limit. Different codes and standards vary greatly in the allowable amount. Plate - the lesser of 1/32? or 5% (typ.)

8. Insufficient Fill Definition: The weld surface is below the adjacent surfaces of the base metal

9. Insufficient Fill on the Root Side (suckback)

10. Cause for Insufficient Fill at the Root

13. Removing a root pass by grinding

15. Excessive Concavity or Convexity Definition: Concavity or convexity of a fillet weld which exceeds the specified allowable limits

18. Reinforcement Excessive Insufficient Improper contour

19. Excessive Reinforcement Definition: Specifically defined by the standard. Typically, Reinforcement should be flush to 1/16?(pipe) or flush to 1/8? (plate or structural shapes).

22. Overlap

24. Burn-through (non-standard)

25. Incomplete or Insufficient Penetration

26. Incomplete Fusion

27. Arc Strike

28. Inclusions Slag Wagontracks Tungsten

32. Inclusions fix when you see it. otherwise grind out & fix

33. Whiskers Unsightly Inhibits material flow in piping Are inclusions Can break off in pipes and damage equipment downline

34. Spatter

35. Arc Craters

36. Cracks Longitudinal Transverse Crater Throat Toe Root Underbead and Heat-affected zone Hot Cold or delayed

46. Repairs to Cracks Determine the cause Correct the problem Take precautions to prevent reoccurrence Generally required to repair using a smaller electrode

47. Base Metal Discontinuities Lamellar tearing Laminations and Delaminations Laps and Seams

48. Laminations

50. Delaminations

51. Laps and Seams

52. Porosity Single Pore Uniformly Scattered Cluster Linear Piping

53. Single Pore Separated by at least their own diameter along the axis of the weld

54. Uniformly Scattered Porosity Typically judged by diameter and proximity to a start or stop often caused by low amperage or short arc gap or an unshielded weld start

55. Cluster Porosity Typically viewed as a single large discontinuity

56. Linear Porosity being linear greatly affects the severity of this discontinuity

57. Piping Porosity Generally has special allowable limits

58. Porosity preheat will help eliminate may need an electrode with more deoxidizers Use run-on/run-off taps restart on top of previous weld and grind off lump

59. Heat-affected zone microstructure alteration add drawing of HAZ of groove weld with leaders to: grain refinement grain growth hardened areas softened areas precipitate suseptable areas.

60. Size or dimension If it renders the part unusable, it is a defect. If it is outside the allowable limit, it renders the part unusable. Things don?t have to be perfect, just within the acceptable tolerance. Working to perfection is too time consuming and costly

61. Hammer marks Stress risers Unsightly Unnecessary

62. REPAIR TECHNIQUES May involve: different process different procedure different preheat/PWHT different electrode smaller electrode


Other Related Presentations

Copyright © 2014 SlideServe. All rights reserved | Powered By DigitalOfficePro