10.5 PREHEATING

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Quiz 1) See the figure below for possible solutions. The thought process behind these is as follows: a) 100% coarse pearlite: We want to keep the temperature above the nose of the IT curve in order for the diffusion process to allow larger growth of the eutectoid (pearlite) structure. b) 100% tempered martensite: We want first to form 100% martensite, which would be by cooling rapidly enough to miss the nose of the IT curve, and to pass completely through the Mf temperature. Then perform a tempering heat treatment at low temperatures for a short (1 hour) period of time. c) 50% coarse pearlite + 25% bainite + 25% martensite: To do this, we will need to have a three step process. First, cool to a temperature above the nose of the IT curve and hold until you have converted 50% of the austenite to coarse pearlite. Second, rapidly cool to a temperature below the nose, but above the Mstart temperature, and hold until 50% of the remaining austenite is converted to bainite (this makes 50% of 50% = 25% bainite). Finally, rapidly quench through the Mf temperature to completely convert the remaining austenite to martensite http://oregonstate.edu/instruct/engr322/Homework/AllHomework/W98/ENGR322HW6.html
Quiz 1) See the figure below for possible solutions. The thought process behind these is as follows: a) 100% coarse pearlite: We want to keep the temperature above the nose of the IT curve in order for the diffusion process to allow larger growth of the eutectoid (pearlite) structure. b) 100% tempered martensite: We want first to form 100% martensite, which would be by cooling rapidly enough to miss the nose of the IT curve, and to pass completely through the Mf temperature. Then perform a tempering heat treatment at low temperatures for a short (1 hour) period of time.
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10.5 PREHEATING
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Preheating
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Preheating
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• Bring temperature up to preheat
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Preheat can be applied using severa
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The temperature of PWHT is selected
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Discussion: However there may also
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Typical PWHT Chart Insertion temper
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PWHT Chart
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PWHT
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PWHT
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PWHT
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PWHT
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PWHT
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PWHT
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PWHT- Local
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PWHT- Local
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PWHT- Local
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PWHT- Local
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PWHT- Equipments
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PWHT- Equipments
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PWHT- Equipments
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PWHT- Equipments
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Fun-Photo: Induction Bending Pipe b
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Fun-Photo: Induction Bending Pipe b
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Other factors can also affect harde
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http://www.azom.com/article.aspx?Ar
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Welding variables, such as heat inp
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Welding- Plate thickness & Weld Geo
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Weld Macro- Geometry
Page 62 and 63: Weld Macro- Geometry
Page 64 and 65: Weld Macro- Geometry
Page 66 and 67: The simplest means to determine har
Page 68 and 69: Jominy Bar
Page 70 and 71: Jominy Bar
Page 72 and 73: It may be important for the welding
Page 74 and 75: Typical Hardness Values Table 11—
Page 76 and 77: HIC
Page 78 and 79: HIC- Hydrogen Induced Cracking
Page 80 and 81: TTT Curve
Page 82 and 83: Martensite
Page 84 and 85: 10.8 MATERIAL TEST REPORTS Material
Page 86 and 87: Billets/Ingots
Page 98 and 99: Product analysis- Pipe
Page 100 and 101: For the purposes of this publicatio
Page 102 and 103: Ductile to brittle transition tempe
Page 104 and 105: Fracture toughness
Page 106 and 107: Charpy impact testing
Page 108 and 109: Elevated mechanical property testin
Page 110 and 111: Further Reading
Page 114: c) 50% coarse pearlite + 25% bainit
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10.5 PREHEATING

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