ASNT Level III- Visual & Optical Testing

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To replicate the surface microstructure, an area is wetted with acetone and a piece of acetate tape is laid on the surface. The tape is drawn by capillary action to the metal surface, producing an accurate negative image of the surface microstructure. Thin acetate tape at 0.025 mm (0.001 in.) provides excellent results and gives the best resolution at high magnifications. Thicker tapes must be pressed onto the test surface and, depending on the expertise of the inspector, smearing can result. Thicker tapes are more costly and the resolution of microscopic detail does not match thinner tapes. Studies of carbide morphology and creep damage mechanisms have been performed at magnifications as high as 10,000 x with thin tape replicas. Before removal of the tape from the test object, the back is coated with paint to provide a reflective surface that enhances microscopic viewing. The replica is removed and can be stored for future analysis. Charlie Chong/ Fion Zhang
If analysis with the scanning electron microscope is needed, replicas should be coated to prevent electron charging. This is accomplished by evaporating or sputter coating a thin conductive film onto the replica surface. Carbon, gold, gold-palladium and other metals are used for coating. There are differences in the sputtering yield from different elements and this should he remembered when choosing an element or when attempting to calculate the thickness of the coating. The main advantage of sputter coating over evaporation techniques is that it provides a continuous coating layer. Complete coating is accomplished without rotating or tilting the replica. With evaporation, only line of sight areas are coated and certain areas typically are coated more than others. 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 and 18: 5.1.2 Fracture Surface Analysis The
Page 19 and 20: Replicas, in the as-stripped condit
Page 21: Microstructural replication is done
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
Page 69 and 70: 6.3.4 Process Control Applications
Page 71 and 72: 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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