ASNT Level III- Visual & Optical Testing

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An example of a replicated fracture surface is shown in Fig. 57. The transmission electron microscope is used in instances where information regarding dislocations and crystallographic planes is needed. Both single stage (negative) and second stage (positive) replicas can be used for failure analysis. Some scanning electron microscope manufacturers offer a reverse imaging module that provides positive images from a negative replica. This eliminates the need to think and interpret in reverse. This feature has also proven valuable for evaluating microstructures through replication. As with the removal of surface debris, it has been found that the thicker replicas provide better results, for the same reasons. The procedure for replication of fracture surfaces is identical to that for debris removal. On rough surfaces, however, difficulty may be encountered when trying to remove the replica. This can cause replication material to remain on the fracture surface but this can easily be removed with acetone. Charlie Chong/ Fion Zhang
Replicas, in the as-stripped condition, typically do not exhibit the contrast needed for resolution of fine microscopic features such as fatigue striations. To improve contrast, shadowing or vapor deposition of a metal is performed. The metal is deposited at an acute angle to the replica surface and collects at different thicknesses at different areas depending on the surface topography. This produces a shadowing that allows greater resolution at higher magnifications. Shadowing with gold or other high atomic number metals enhances the electron beam interaction with the sample and greatly improves the image in the scanning electron microscope by reducing the signal-tonoise ratio. Charlie Chong/ Fion Zhang
Page 1 and 2: ASNT Level III- Visual & Optical Te
Page 3 and 4: At works Charlie Chong/ Fion Zhang
Page 5 and 6: Charlie Chong/ Fion Zhang Fion Zhan
Page 7 and 8: SECTION 4: BASIC AIDS AND ACCESSORI
Page 9 and 10: PART 4: MACHINE VISION TECHNOLOGY 4
Page 11 and 12: PART 6: TEMPERATURE INDICATING MATE
Page 13 and 14: PART 4: MACHINE VISION TECHNOLOGY 1
Page 15 and 16: 5.1 Cellulose Acetate Replication A
Page 17: 5.1.2 Fracture Surface Analysis The
Page 21 and 22: Microstructural replication is done
Page 23 and 24: If analysis with the scanning elect
Page 25 and 26: Sputter deposition is a physical va
Page 27 and 28: Sputtering http://en.wikipedia.org/
Page 29 and 30: Sputtering http://clearmetalsinc.co
Page 31 and 32: Sputter Deposition Charlie Chong/ F
Page 33 and 34: 5.1.4 Strain Replication The replic
Page 35 and 36: FIGURE 56. Principles of acetate ta
Page 37 and 38: Fatigue striations Charlie Chong/ F
Page 39 and 40: FIGURE 59. Documentation of creep d
Page 41 and 42: FIGURE 60. Documentation of stress
Page 43 and 44: TABLE 14. Action required for creep
Page 45 and 46: Cellulose Acetate Replication http:
Page 47 and 48: Replication Microscopy Techniques f
Page 49 and 50: Replication Microscopy Techniques f
Page 51 and 52: 5.2.1 Use of Silicone Replicating M
Page 53 and 54: FIGURE 63. Silicon replicas used to
Page 55 and 56: Brittle Failure Chevron Marking Cha
Page 57 and 58: PART 6: TEMPERATURE INDICATING MATE
Page 59 and 60: Temperature indicating sticks were
Page 61 and 62: Levels of Charlie Chong/ Fion Zhang
Page 63 and 64: 6.2 Certification of Temperature In
Page 65 and 66: 6.3 Applications for Temperature In
Page 67 and 68: 6.3.2 Verifying Oven Temperatures T
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6.3.4 Process Control Applications
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6.3.6 Precise Post forming Heat Con
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Another example of handforrning is
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6.3.7 Pipeline Coatings Epoxy powde
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The most common use for temperature
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FIGURE 67. Temperature indicating s
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PART 7: CHEMICAL AIDS 7.0 General T
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7.1 Test Object Selection Figure 68
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7.2 Surface Preparation Preparation
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7.2.2 Removing Rust and Scale Rust
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If the required finish cannot be ac
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FIGURE 70. Example of contrast reve
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7.3.2 Safety Precautions Etchants a
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Etchant Safety Charlie Chong/ Fion
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Etchant Safety Charlie Chong/ Fion
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7.3.3 Containers Containers used wi
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1. add the acid or alkali to the wa
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7.3.6 Disposal Before disposing of
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7.4.2 Swabbing Etching may also be
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7.4.4 Test Object Preservation Rins
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7.5 Conclusion Visual testing is pe
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Cellulose Replica Sheets Charlie Ch
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Charlie Chong/ Fion Zhang
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ASNT Level III- Visual & Optical Testing

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