UT Product Technology TWI
Product Technology Steel Production Wrought Production Extrusion Forging Rolling Casting Welding Defects  Inherent Process...
2 Stage Process <ul><li>Iron ore is reduced into pig iron assisted by other materials. </li></ul><ul><li>Carbon content of...
1st Stage  <ul><li>Iron ore is reduced into pig iron assisted by other materials. </li></ul><ul><li>Raw materials  Hematit...
1st Stage <ul><li>Blast furnace reactions </li></ul>Steel Production <ul><li>Fe 2 O 3  + 3CO = 2Fe + 3CO 2 </li></ul><ul><...
Blast Furnace <ul><li>Charge </li></ul><ul><li>Ore 4000 </li></ul><ul><li>Limestone 800 </li></ul><ul><li>Coke 1800 </li><...
Blast Furnace Steel Production Product of Blast Furnace - Pig iron (>3% carbon)
Steel Production <ul><li>Pig iron converted to steel by blowing molten metal with oxygen or oxygen rich gases </li></ul><u...
Steel Production <ul><li>Bessemer  </li></ul><ul><li>Open hearth process </li></ul><ul><li>Basic oxygen process </li></ul>
Steel Production <ul><li>Basic oxygen process </li></ul>Solid scrap
Steel Production <ul><li>Basic oxygen process </li></ul>Molten Pig Iron
Steel Production <ul><li>Basic oxygen process </li></ul>Oxygen lance
Steel Production <ul><li>Basic oxygen process </li></ul>Steel
Steel Production Molten steel poured into large molds (ingots)  Ingots are used for further processing Hot top
Steel Production Molten steel poured into large molds (ingots)  Ingots are used for further processing 2 types of mould - ...
Steel Production <ul><li>Metal solidifies from outside inwards </li></ul><ul><li>3 types of crystal formed </li></ul><ul><...
Smelting Defects <ul><li>Pipes </li></ul><ul><li>Shrinkage  </li></ul>Primary pipe/sink Secondary pipe
Smelting Defects <ul><li>Non-metallic inclusions </li></ul>
Smelting Defects <ul><li>Segregation of metals </li></ul>
Steel Production <ul><li>Alternative to ingots is Continuous casting </li></ul>Tundish Mold forming slab Water spray chamb...
Steel Production
Advantages of Continuous casting <ul><li>Faster : 300 tons of steel in 45 mins  compared to 12 hours </li></ul><ul><li>No ...
Product Technology Casting
Casting Process <ul><li>Liquid metal is caused to fill a cavity and solidify into a useful shape </li></ul><ul><li>All mat...
Casting Process <ul><li>Stage 1 : A pattern of the finished  item slightly over sized </li></ul><ul><li>Stage 2 : Mould co...
Casting Riser Pouring basin Runner Sprue Core
Casting Chaplets Chills
Casting <ul><li>Casting involves the solidification from liquid to solid </li></ul><ul><li>Solidification proceeds from ou...
Grain Growth
Casting Methods <ul><li>Sand casting </li></ul>
Sand Casting
Sand Casting
Sand Casting
Sand Casting
Sand Casting
Sand Casting
Casting Methods <ul><li>Sand casting </li></ul><ul><li>Die casting / Injection moulding </li></ul>
Die Casting Injection piston Casting cavity Die Fixed platen Moving platen
Casting Methods <ul><li>Sand casting </li></ul><ul><li>Die casting / Injection moulding </li></ul><ul><li>Investment casti...
Investment Casting Wax Pattern
Investment Casting Coat with refractory slurry
Investment Casting Reinforce with plaster backing (Investment)
Investment Casting Oven dry to liquify or vaporise pattern and dry mould
Investment Casting Pour metal
Investment Casting Remove investment material
Choice of Casting Method <ul><li>Dimensional Accuracy </li></ul><ul><li>Investment casting </li></ul><ul><li>Die casting <...
Casting Defects <ul><li>Shrinkage cavities </li></ul><ul><li>Sinks </li></ul>Primary pipe/sink Secondary pipe
Casting Defects <ul><li>Blowholes and porosity </li></ul>Cross-sectional changes /corners
Casting Defects <ul><li>Inclusions </li></ul><ul><li>Scabs </li></ul><ul><li>Fins  </li></ul>
Casting Defects <ul><li>Shrinkage </li></ul>
Casting Defects <ul><li>Scabs </li></ul>
Casting Defects <ul><li>Scabs-  part of mould stuck to the casting </li></ul>
Casting Defects <ul><li>Fins </li></ul>Gaps
Casting Defects <ul><li>Fins-  excess metal of casting </li></ul>Fin
Casting Defects <ul><li>Hot tears </li></ul>The larger section cools slower than the smaller section The grain are differe...
Hot Tears
<ul><li>Chills are used for: </li></ul><ul><li>Directional grain growth </li></ul><ul><li>Uniform cooling rate </li></ul>
Casting Defects <ul><li>Segregation </li></ul>
Product Technology Wrought Production Methods
Wrought Production <ul><li>Forging </li></ul><ul><li>Extrusion </li></ul><ul><li>Rolling  </li></ul>
Wrought Production <ul><li>Forging </li></ul><ul><li>Metal confined under pressure to cause plastic flow </li></ul><ul><li...
Rolling Two-High Reversing Mill Ingots, slabs and billets rolled to produce long length products with uniform cross sectio...
Rolling Two-High Reversing Mill PRIMARY ROLLING PROCESS   Secondary piping
Rolling Three-High Reversing Mill SECONDARY ROLLING PROCESS   Lamination
Rolling Two-High Reversing Mill PRIMARY ROLLING PROCESS   Non-metallic inclusion
Rolling Three-High Reversing Mill SECONDARY ROLLING PROCESS   Stringers
Rolling Two-High Reversing Mill PRIMARY ROLLING PROCESS   Segregation of metals
Rolling Three-High Reversing Mill SECONDARY ROLLING PROCESS   Banding
Cold Rolling <ul><li>Initial rolling hot </li></ul><ul><li>Finishing by cold working </li></ul>Cluster mill 4 High mill
Rolling <ul><li>Bloom - Square c/s 150x150mm minimum </li></ul><ul><li>Slab - Rectangular c/s area greater than 14400 mm 2...
Forging Hammer Anvil Blacksmith
Forging <ul><li>6 basic actions </li></ul><ul><li>Upsetting  </li></ul><ul><li>Swaging  </li></ul><ul><li>Bending  </li></...
Forging Hammer (Tup) Anvil Blacksmith / Open die forging
Forging <ul><li>Pressure forging </li></ul>
Forging <ul><li>Closed die  </li></ul>
Extrusion <ul><li>Direct </li></ul><ul><li>Indirect </li></ul><ul><li>Impact </li></ul><ul><li>High loads used to shape fe...
Direct Extrusion Billet Ram Die
Indirect Extrusion Die Extruded item Billet
Impact Extrusion Die Blank Punch
Extrusion Defects <ul><li>Oxide films  (‘Extrusion’ defect) </li></ul><ul><li>Surface cracks </li></ul><ul><li>Grain struc...
Impact Extrusion
Wrought Production Defects <ul><li>Cracks </li></ul><ul><li>Laps  </li></ul><ul><li>Seams </li></ul><ul><li>Stringers </li...
Wrought Production Defects <ul><li>Banding </li></ul><ul><li>Excessive flash </li></ul><ul><li>Lack of fill </li></ul><ul>...
Other Wrought Processes <ul><li>Drawing </li></ul><ul><li>Material is reduced or changed in profile by pulling through a d...
Other Wrought Processes <ul><li>Drawing </li></ul><ul><li>Material is reduced or changed in profile by pulling through a d...
Product Technology Welding
A Weld : Definitions <ul><li>A union between pieces of metal at faces rendered plastic or liquid by heat,pressure or both....
Welds <ul><li>An ideal weld must give a strong bond between materials with the interfaces disappearing </li></ul><ul><li>T...
Welding <ul><li>A union between pieces of metal at faces rendered plastic or liquid by heat,pressure or both. </li></ul><u...
Electric Arc Welding Power supply Work piece Electrode Clamp(Earth)
Electric Arc Welding <ul><li>Electric discharge produced between cathode and anode by a potential difference (40 to 60 vol...
Electric Arc Welding <ul><li>Arc Welding Processes </li></ul><ul><li>Manual metal arc </li></ul><ul><li>Tungsten Inert Gas...
Zones in Fusion Welds <ul><li>Fusion Zone  </li></ul>
Zones in Fusion Welds <ul><li>Fusion Zone  </li></ul><ul><li>Heat Affected Zone  </li></ul>
Zones in Fusion Welds <ul><li>Fusion Zone  </li></ul><ul><li>Heat Affected Zone  </li></ul><ul><li>Parent Material or Base...
Joint Design Butt  Weld
Joint Design Butt  Weld Lap Joint
Joint Design Butt  Weld Corner Joint Lap Joint
Joint Design Butt  Weld Corner Joint Lap Joint Edge  Weld
Joint Design Butt  Weld Corner Joint Lap Joint T Joint Edge  Weld
 
Manual Metal Arc (MMA) Consumable electrode Flux coating Core wire Arc Evolved gas shield Parent metal Slag Weld metal
Manual Metal Arc Welding <ul><li>Shielding provided by decomposition of flux covering </li></ul><ul><li>Electrode consumab...
Tungsten Inert Gas (TIG) Non-consumable tungsten electrode Arc Parent metal Weld metal Gas shield Filler wire Gas nozzle
Metal Inert Gas (MIG) Consumable  electrode(filler wire) Arc Parent metal Weld metal Gas shield Gas nozzle Reel feed
Submerged Arc  Consumable  electrode Reel feed Flux feed Flux retrieval Parent metal Weld metal Slag
Electroslag Filler wire Molten   flux Weld metal Water cooled copper shoes
Welding Defects <ul><li>4 Crack Types </li></ul><ul><li>Solidification cracks </li></ul><ul><li>Hydrogen induced cracks </...
Welding Defects <ul><li>Classified by Shape </li></ul><ul><li>Longitudinal </li></ul><ul><li>Transverse </li></ul><ul><li>...
Welding Defects <ul><li>Solidification </li></ul><ul><li>Occurs during weld solidification process </li></ul><ul><li>Steel...
Welding Defects <ul><li>Hydrogen Induced </li></ul><ul><li>Requires susceptible grain structure, stress and hydrogen  </li...
Welding Defects <ul><li>Lamellar Tearing </li></ul><ul><li>Step like appearance  </li></ul><ul><li>Occurs in parent materi...
Welding Defects <ul><li>Re-Heat Cracking </li></ul><ul><li>Occurs mainly in HAZ of low alloy steels during post weld heat ...
Welding Defects <ul><li>Incomplete root penetration </li></ul><ul><li>Causes </li></ul><ul><li>Too large or small a root g...
Welding Defects <ul><li>Root concavity </li></ul><ul><li>Causes </li></ul><ul><li>Root gap too large </li></ul><ul><li>Ins...
Welding Defects <ul><li>Lack of fusion </li></ul><ul><li>Causes </li></ul><ul><li>Contaminated weld preparation </li></ul>...
Welding Defects <ul><li>Undercut </li></ul><ul><li>Causes </li></ul><ul><li>Excessive welding current </li></ul><ul><li>We...
Welding Defects <ul><li>Incompletely Filled Groove </li></ul><ul><li>Causes </li></ul><ul><li>Insufficient weld metal depo...
Welding Defects <ul><li>Gas pores / Porosity </li></ul><ul><li>Causes </li></ul><ul><li>Excessive moisture in flux or prep...
Welding Defects <ul><li>Inclusions - Slag </li></ul><ul><li>Causes </li></ul><ul><li>Insufficient cleaning between passes ...
Welding Defects <ul><li>Inclusions - Tungsten </li></ul><ul><li>Causes </li></ul><ul><li>Contamination of weld during TIG ...
Welding Defects <ul><li>Burn Through </li></ul><ul><li>Causes </li></ul><ul><li>Excessive amperage during welding of root ...
Welding Defects <ul><li>Arc Strikes </li></ul><ul><li>Causes </li></ul><ul><li>Electrode straying onto parent metal </li><...
Steel Metallurgy <ul><li>Steel- Iron and carbon alloyed with other elements  </li></ul><ul><li>Carbon- Strength, hardness,...
Steel Metallurgy <ul><li>Steel- Iron and carbon alloyed with other elements  </li></ul>BCC FCC
Steel Metallurgy Low Stress Increased Stress Elastic Deformation Plastic Deformation
Heat Treatment  <ul><li>Softening </li></ul><ul><li>Hardening </li></ul><ul><li>Tempering </li></ul><ul><li>Stress Relief ...
Heat Treatment 900 850 800 750 700 Ar3 Ac1 Ac2 Ac3 Ar1 Ar2 1 2 Minutes to raise temperature by 10 C
Iron Carbide Diagram Ac3 Ac1 .2  .4  .6  .8  1  1.2  1.4  1.6  1.8  2 Carbon % 1000 900 800 700 600
Iron Carbide Diagram Ac3 Ac1 .2  .4  .6  .8  1  1.2  1.4  1.6  1.8  2 Carbon % 1000 900 800 700 600 Austenite Ferrite and ...
Heat Treatment   <ul><li>Hardening </li></ul><ul><li>Produce hard but brittle material </li></ul><ul><li>Heat to above tra...
Heat Treatment   <ul><li>Stress Relief </li></ul><ul><li>Relax stresses without significant changes in the metallurgical s...
Heat Treatment   <ul><li>Full Annealing </li></ul><ul><li>Produces very soft low hardness material for machining or cold w...
Heat Treatment   <ul><li>Sub Critical Annealing </li></ul><ul><li>Spheroidizing produces soft low hardness material cheape...
Heat Treatment   <ul><li>Normalising </li></ul><ul><li>Maintains and improves mechanical properties and modifies grain str...
Nature and Origin of Defects <ul><li>Inherent </li></ul><ul><li>Processing </li></ul><ul><li>In Service </li></ul>
Heat Induced Defects <ul><li>Heat treatment cracks </li></ul><ul><li>Grinding cracks </li></ul><ul><li>Friction induced cr...
In Service Cracks <ul><li>Fatigue cracks </li></ul><ul><li>Stress corrosion cracks </li></ul><ul><li>Hydrogen induced crac...
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Ut P5 (Product Tech.)

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  • Ut P5 (Product Tech.)

    1. 1. UT Product Technology TWI
    2. 2. Product Technology Steel Production Wrought Production Extrusion Forging Rolling Casting Welding Defects Inherent Processing Service Heat Treatment
    3. 3. 2 Stage Process <ul><li>Iron ore is reduced into pig iron assisted by other materials. </li></ul><ul><li>Carbon content of Pig Iron is lowered by reacting with oxygen </li></ul><ul><li>The molten metal is then cast into Ingots or continuously cast </li></ul><ul><li>Ingots are rolled into Blooms, Billets or Slabs </li></ul>Steel Production
    4. 4. 1st Stage <ul><li>Iron ore is reduced into pig iron assisted by other materials. </li></ul><ul><li>Raw materials Hematite (Fe 2 O 3 ) or Magnetite( Fe 3 O 4 ) + Coke Limestone Air </li></ul>Steel Production
    5. 5. 1st Stage <ul><li>Blast furnace reactions </li></ul>Steel Production <ul><li>Fe 2 O 3 + 3CO = 2Fe + 3CO 2 </li></ul><ul><li>Fe 2 O 3 + 3C = 2Fe + 3CO </li></ul><ul><li>SiO 2 + 2Cao = 2CaOSiO 2 </li></ul>Lime from limestone combines with impurities (mainly silica) in the ore to form fluid slag
    6. 6. Blast Furnace <ul><li>Charge </li></ul><ul><li>Ore 4000 </li></ul><ul><li>Limestone 800 </li></ul><ul><li>Coke 1800 </li></ul><ul><li>Air 8000 </li></ul><ul><li>14600 </li></ul><ul><li>Products </li></ul><ul><li>Pig Iron 2000 </li></ul><ul><li>Slag 1600 </li></ul><ul><li>Dust 200 </li></ul><ul><li>Furnace gas 10800 </li></ul><ul><li>14600 </li></ul>Steel Production
    7. 7. Blast Furnace Steel Production Product of Blast Furnace - Pig iron (>3% carbon)
    8. 8. Steel Production <ul><li>Pig iron converted to steel by blowing molten metal with oxygen or oxygen rich gases </li></ul><ul><li>Oxygen reacts with excess carbon </li></ul><ul><li>C + 2 O  CO 2 </li></ul><ul><li>C + O  CO </li></ul><ul><li>CO + O  CO 2 </li></ul>
    9. 9. Steel Production <ul><li>Bessemer </li></ul><ul><li>Open hearth process </li></ul><ul><li>Basic oxygen process </li></ul>
    10. 10. Steel Production <ul><li>Basic oxygen process </li></ul>Solid scrap
    11. 11. Steel Production <ul><li>Basic oxygen process </li></ul>Molten Pig Iron
    12. 12. Steel Production <ul><li>Basic oxygen process </li></ul>Oxygen lance
    13. 13. Steel Production <ul><li>Basic oxygen process </li></ul>Steel
    14. 14. Steel Production Molten steel poured into large molds (ingots) Ingots are used for further processing Hot top
    15. 15. Steel Production Molten steel poured into large molds (ingots) Ingots are used for further processing 2 types of mould - Narrow end up, Wide end up
    16. 16. Steel Production <ul><li>Metal solidifies from outside inwards </li></ul><ul><li>3 types of crystal formed </li></ul><ul><li>Chill or fine exui-axed </li></ul><ul><li>Columnar </li></ul><ul><li>Large equi-axed </li></ul>
    17. 17. Smelting Defects <ul><li>Pipes </li></ul><ul><li>Shrinkage </li></ul>Primary pipe/sink Secondary pipe
    18. 18. Smelting Defects <ul><li>Non-metallic inclusions </li></ul>
    19. 19. Smelting Defects <ul><li>Segregation of metals </li></ul>
    20. 20. Steel Production <ul><li>Alternative to ingots is Continuous casting </li></ul>Tundish Mold forming slab Water spray chamber Rollers
    21. 21. Steel Production
    22. 22. Advantages of Continuous casting <ul><li>Faster : 300 tons of steel in 45 mins compared to 12 hours </li></ul><ul><li>No piping problems </li></ul><ul><li>Cheaper : No ingot molds, handling </li></ul>Steel Production
    23. 23. Product Technology Casting
    24. 24. Casting Process <ul><li>Liquid metal is caused to fill a cavity and solidify into a useful shape </li></ul><ul><li>All materials used in metal manufacture cast at some time </li></ul>
    25. 25. Casting Process <ul><li>Stage 1 : A pattern of the finished item slightly over sized </li></ul><ul><li>Stage 2 : Mould constructed from the pattern </li></ul><ul><li>Stage 3 : Liquid metal poured through the channels to fill the mould </li></ul>
    26. 26. Casting Riser Pouring basin Runner Sprue Core
    27. 27. Casting Chaplets Chills
    28. 28. Casting <ul><li>Casting involves the solidification from liquid to solid </li></ul><ul><li>Solidification proceeds from outside to centre </li></ul><ul><li>Solidification involves shrinkage </li></ul>
    29. 29. Grain Growth
    30. 30. Casting Methods <ul><li>Sand casting </li></ul>
    31. 31. Sand Casting
    32. 32. Sand Casting
    33. 33. Sand Casting
    34. 34. Sand Casting
    35. 35. Sand Casting
    36. 36. Sand Casting
    37. 37. Casting Methods <ul><li>Sand casting </li></ul><ul><li>Die casting / Injection moulding </li></ul>
    38. 38. Die Casting Injection piston Casting cavity Die Fixed platen Moving platen
    39. 39. Casting Methods <ul><li>Sand casting </li></ul><ul><li>Die casting / Injection moulding </li></ul><ul><li>Investment casting / Lost wax process </li></ul>
    40. 40. Investment Casting Wax Pattern
    41. 41. Investment Casting Coat with refractory slurry
    42. 42. Investment Casting Reinforce with plaster backing (Investment)
    43. 43. Investment Casting Oven dry to liquify or vaporise pattern and dry mould
    44. 44. Investment Casting Pour metal
    45. 45. Investment Casting Remove investment material
    46. 46. Choice of Casting Method <ul><li>Dimensional Accuracy </li></ul><ul><li>Investment casting </li></ul><ul><li>Die casting </li></ul><ul><li>Sand casting </li></ul><ul><li>Cost </li></ul><ul><li>Sand casting </li></ul><ul><li>Die casting </li></ul><ul><li>Investment casting </li></ul>
    47. 47. Casting Defects <ul><li>Shrinkage cavities </li></ul><ul><li>Sinks </li></ul>Primary pipe/sink Secondary pipe
    48. 48. Casting Defects <ul><li>Blowholes and porosity </li></ul>Cross-sectional changes /corners
    49. 49. Casting Defects <ul><li>Inclusions </li></ul><ul><li>Scabs </li></ul><ul><li>Fins </li></ul>
    50. 50. Casting Defects <ul><li>Shrinkage </li></ul>
    51. 51. Casting Defects <ul><li>Scabs </li></ul>
    52. 52. Casting Defects <ul><li>Scabs- part of mould stuck to the casting </li></ul>
    53. 53. Casting Defects <ul><li>Fins </li></ul>Gaps
    54. 54. Casting Defects <ul><li>Fins- excess metal of casting </li></ul>Fin
    55. 55. Casting Defects <ul><li>Hot tears </li></ul>The larger section cools slower than the smaller section The grain are different between the sections Hot Tears
    56. 56. Hot Tears
    57. 57. <ul><li>Chills are used for: </li></ul><ul><li>Directional grain growth </li></ul><ul><li>Uniform cooling rate </li></ul>
    58. 58. Casting Defects <ul><li>Segregation </li></ul>
    59. 59. Product Technology Wrought Production Methods
    60. 60. Wrought Production <ul><li>Forging </li></ul><ul><li>Extrusion </li></ul><ul><li>Rolling </li></ul>
    61. 61. Wrought Production <ul><li>Forging </li></ul><ul><li>Metal confined under pressure to cause plastic flow </li></ul><ul><li>Extrusion </li></ul><ul><li>Metal forced through a die under a large load </li></ul><ul><li>Rolling </li></ul><ul><li>Thickness reduction through compression </li></ul>
    62. 62. Rolling Two-High Reversing Mill Ingots, slabs and billets rolled to produce long length products with uniform cross section PRIMARY ROLLING PROCESS / COGGING
    63. 63. Rolling Two-High Reversing Mill PRIMARY ROLLING PROCESS Secondary piping
    64. 64. Rolling Three-High Reversing Mill SECONDARY ROLLING PROCESS Lamination
    65. 65. Rolling Two-High Reversing Mill PRIMARY ROLLING PROCESS Non-metallic inclusion
    66. 66. Rolling Three-High Reversing Mill SECONDARY ROLLING PROCESS Stringers
    67. 67. Rolling Two-High Reversing Mill PRIMARY ROLLING PROCESS Segregation of metals
    68. 68. Rolling Three-High Reversing Mill SECONDARY ROLLING PROCESS Banding
    69. 69. Cold Rolling <ul><li>Initial rolling hot </li></ul><ul><li>Finishing by cold working </li></ul>Cluster mill 4 High mill
    70. 70. Rolling <ul><li>Bloom - Square c/s 150x150mm minimum </li></ul><ul><li>Slab - Rectangular c/s area greater than 14400 mm 2 </li></ul><ul><li>Billet - Square 50x50 up to 120 x 120mm </li></ul><ul><li>Primary rolling- ingot to blooms and slabs </li></ul><ul><li>Secondary rolling - blooms and slabs to plates , sheets etc </li></ul>
    71. 71. Forging Hammer Anvil Blacksmith
    72. 72. Forging <ul><li>6 basic actions </li></ul><ul><li>Upsetting </li></ul><ul><li>Swaging </li></ul><ul><li>Bending </li></ul><ul><li>Welding </li></ul><ul><li>Punching </li></ul><ul><li>Cutting out </li></ul>
    73. 73. Forging Hammer (Tup) Anvil Blacksmith / Open die forging
    74. 74. Forging <ul><li>Pressure forging </li></ul>
    75. 75. Forging <ul><li>Closed die </li></ul>
    76. 76. Extrusion <ul><li>Direct </li></ul><ul><li>Indirect </li></ul><ul><li>Impact </li></ul><ul><li>High loads used to shape ferrous and non-ferrous alloys </li></ul><ul><li>Items produced are of uniform cross section </li></ul>
    77. 77. Direct Extrusion Billet Ram Die
    78. 78. Indirect Extrusion Die Extruded item Billet
    79. 79. Impact Extrusion Die Blank Punch
    80. 80. Extrusion Defects <ul><li>Oxide films (‘Extrusion’ defect) </li></ul><ul><li>Surface cracks </li></ul><ul><li>Grain structure variation </li></ul>
    81. 81. Impact Extrusion
    82. 82. Wrought Production Defects <ul><li>Cracks </li></ul><ul><li>Laps </li></ul><ul><li>Seams </li></ul><ul><li>Stringers </li></ul><ul><li>Slugs </li></ul><ul><li>Bursts </li></ul><ul><li>Laminations </li></ul>
    83. 83. Wrought Production Defects <ul><li>Banding </li></ul><ul><li>Excessive flash </li></ul><ul><li>Lack of fill </li></ul><ul><li>Mismatch </li></ul><ul><li>Internal cracking </li></ul><ul><li>Mechanical marks </li></ul>
    84. 84. Other Wrought Processes <ul><li>Drawing </li></ul><ul><li>Material is reduced or changed in profile by pulling through a die </li></ul>Die Wire or rod Force
    85. 85. Other Wrought Processes <ul><li>Drawing </li></ul><ul><li>Material is reduced or changed in profile by pulling through a die </li></ul>Die Tube Force Mandrel
    86. 86. Product Technology Welding
    87. 87. A Weld : Definitions <ul><li>A union between pieces of metal at faces rendered plastic or liquid by heat,pressure or both. </li></ul><ul><li>BS 499 </li></ul><ul><li>A continuous defect surrounded by parent material </li></ul><ul><li>NASA </li></ul>
    88. 88. Welds <ul><li>An ideal weld must give a strong bond between materials with the interfaces disappearing </li></ul><ul><li>To achieve this </li></ul><ul><li>Smooth,flat or matching surfaces </li></ul><ul><li>Surfaces shall be free from contaminants </li></ul><ul><li>Metals shall be free from impurities </li></ul><ul><li>Metals shall have identical crystalline structures </li></ul>
    89. 89. Welding <ul><li>A union between pieces of metal at faces rendered plastic or liquid by heat,pressure or both. </li></ul><ul><li>BS 499 </li></ul><ul><li>Ultrasonics </li></ul><ul><li>Electron beam </li></ul><ul><li>Friction </li></ul><ul><li>Electric resistance </li></ul><ul><li>Electric arc </li></ul>Possible energy sources
    90. 90. Electric Arc Welding Power supply Work piece Electrode Clamp(Earth)
    91. 91. Electric Arc Welding <ul><li>Electric discharge produced between cathode and anode by a potential difference (40 to 60 volts) </li></ul><ul><li>Discharge ionises air and produces -ve electrons and +ve ions </li></ul><ul><li>Electrons impact upon anode, ions upon cathode </li></ul><ul><li>Impact of particles converts kinetic energy to heat (7000 o C) and light </li></ul><ul><li>Amperage controls number of ions and electrons, Voltage controls their velocity </li></ul>
    92. 92. Electric Arc Welding <ul><li>Arc Welding Processes </li></ul><ul><li>Manual metal arc </li></ul><ul><li>Tungsten Inert Gas </li></ul><ul><li>Metal Inert Gas </li></ul><ul><li>Submerged Arc </li></ul>Differences between them <ul><li>Methods of shielding the arc </li></ul><ul><li>Consumable or Non-consumable electrode </li></ul><ul><li>Degree of automation </li></ul>
    93. 93. Zones in Fusion Welds <ul><li>Fusion Zone </li></ul>
    94. 94. Zones in Fusion Welds <ul><li>Fusion Zone </li></ul><ul><li>Heat Affected Zone </li></ul>
    95. 95. Zones in Fusion Welds <ul><li>Fusion Zone </li></ul><ul><li>Heat Affected Zone </li></ul><ul><li>Parent Material or Base Metal </li></ul>
    96. 96. Joint Design Butt Weld
    97. 97. Joint Design Butt Weld Lap Joint
    98. 98. Joint Design Butt Weld Corner Joint Lap Joint
    99. 99. Joint Design Butt Weld Corner Joint Lap Joint Edge Weld
    100. 100. Joint Design Butt Weld Corner Joint Lap Joint T Joint Edge Weld
    101. 102. Manual Metal Arc (MMA) Consumable electrode Flux coating Core wire Arc Evolved gas shield Parent metal Slag Weld metal
    102. 103. Manual Metal Arc Welding <ul><li>Shielding provided by decomposition of flux covering </li></ul><ul><li>Electrode consumable </li></ul><ul><li>Manual process </li></ul><ul><li>Welder controls </li></ul><ul><li>Arc length </li></ul><ul><li>Angle of electrode </li></ul><ul><li>Speed of travel </li></ul><ul><li>Amperage settings </li></ul>
    103. 104. Tungsten Inert Gas (TIG) Non-consumable tungsten electrode Arc Parent metal Weld metal Gas shield Filler wire Gas nozzle
    104. 105. Metal Inert Gas (MIG) Consumable electrode(filler wire) Arc Parent metal Weld metal Gas shield Gas nozzle Reel feed
    105. 106. Submerged Arc Consumable electrode Reel feed Flux feed Flux retrieval Parent metal Weld metal Slag
    106. 107. Electroslag Filler wire Molten flux Weld metal Water cooled copper shoes
    107. 108. Welding Defects <ul><li>4 Crack Types </li></ul><ul><li>Solidification cracks </li></ul><ul><li>Hydrogen induced cracks </li></ul><ul><li>Lamellar tearing </li></ul><ul><li>Reheat cracks </li></ul>Cracks
    108. 109. Welding Defects <ul><li>Classified by Shape </li></ul><ul><li>Longitudinal </li></ul><ul><li>Transverse </li></ul><ul><li>Branched </li></ul><ul><li>Chevron </li></ul>Cracks <ul><li>Classified by Position </li></ul><ul><li>HAZ </li></ul><ul><li>Centreline </li></ul><ul><li>Crater </li></ul><ul><li>Fusion zone </li></ul><ul><li>Parent metal </li></ul>
    109. 110. Welding Defects <ul><li>Solidification </li></ul><ul><li>Occurs during weld solidification process </li></ul><ul><li>Steels with high sulphur content (low ductility at elevated temperature) </li></ul><ul><li>Requires high tensile stress </li></ul><ul><li>Occur longitudinally down centre of weld </li></ul><ul><li>eg Crater cracking </li></ul>Cracks
    110. 111. Welding Defects <ul><li>Hydrogen Induced </li></ul><ul><li>Requires susceptible grain structure, stress and hydrogen </li></ul><ul><li>Hydrogen enters via welding arc </li></ul><ul><li>Hydrogen source - atmosphere or contamination of preparation or electrode </li></ul><ul><li>Moisture diffuses out into parent metal on cooling </li></ul><ul><li>Most likely in HAZ </li></ul>Cracks
    111. 112. Welding Defects <ul><li>Lamellar Tearing </li></ul><ul><li>Step like appearance </li></ul><ul><li>Occurs in parent material or HAZ </li></ul><ul><li>Only in rolled direction of the parent material </li></ul><ul><li>Associated with restrained joints subjected to through thickness stresses on corners, tees and fillets </li></ul><ul><li>Requires high sulphur or non-metallic inclusions </li></ul>Cracks
    112. 113. Welding Defects <ul><li>Re-Heat Cracking </li></ul><ul><li>Occurs mainly in HAZ of low alloy steels during post weld heat treatment or service at elevated temperatures </li></ul><ul><li>Occurs in areas of high stress and existing defects </li></ul><ul><li>Prevented by toe grinding, elimination of poor profile material selection and controlled post weld heat treatment </li></ul>Cracks
    113. 114. Welding Defects <ul><li>Incomplete root penetration </li></ul><ul><li>Causes </li></ul><ul><li>Too large or small a root gap </li></ul><ul><li>Arc too long </li></ul><ul><li>Wrong polarity </li></ul><ul><li>Electrode too large for joint preparation </li></ul><ul><li>Incorrect electrode angle </li></ul><ul><li>Too fast a speed of travel for current </li></ul>
    114. 115. Welding Defects <ul><li>Root concavity </li></ul><ul><li>Causes </li></ul><ul><li>Root gap too large </li></ul><ul><li>Insufficient arc energy </li></ul><ul><li>Excessive back purge (TIG) </li></ul>
    115. 116. Welding Defects <ul><li>Lack of fusion </li></ul><ul><li>Causes </li></ul><ul><li>Contaminated weld preparation </li></ul><ul><li>Amperage too low </li></ul><ul><li>Amperage too high (welder increases speed of travel) </li></ul>
    116. 117. Welding Defects <ul><li>Undercut </li></ul><ul><li>Causes </li></ul><ul><li>Excessive welding current </li></ul><ul><li>Welding speed too high </li></ul><ul><li>Incorrect electrode angle </li></ul><ul><li>Excessive weave </li></ul><ul><li>Electrode too large </li></ul>
    117. 118. Welding Defects <ul><li>Incompletely Filled Groove </li></ul><ul><li>Causes </li></ul><ul><li>Insufficient weld metal deposited </li></ul><ul><li>Improper welding technique </li></ul>
    118. 119. Welding Defects <ul><li>Gas pores / Porosity </li></ul><ul><li>Causes </li></ul><ul><li>Excessive moisture in flux or preparation </li></ul><ul><li>Contaminated preparation </li></ul><ul><li>Low welding current </li></ul><ul><li>Arc length too long </li></ul><ul><li>Damaged electrode flux </li></ul><ul><li>Removal of gas shield </li></ul>
    119. 120. Welding Defects <ul><li>Inclusions - Slag </li></ul><ul><li>Causes </li></ul><ul><li>Insufficient cleaning between passes </li></ul><ul><li>Contaminated weld preparation </li></ul><ul><li>Welding over irregular profile </li></ul><ul><li>Incorrect welding speed </li></ul><ul><li>Arc length too long </li></ul>
    120. 121. Welding Defects <ul><li>Inclusions - Tungsten </li></ul><ul><li>Causes </li></ul><ul><li>Contamination of weld during TIG welding process </li></ul>
    121. 122. Welding Defects <ul><li>Burn Through </li></ul><ul><li>Causes </li></ul><ul><li>Excessive amperage during welding of root </li></ul><ul><li>Excessive root grinding </li></ul><ul><li>Improper welding technique </li></ul>
    122. 123. Welding Defects <ul><li>Arc Strikes </li></ul><ul><li>Causes </li></ul><ul><li>Electrode straying onto parent metal </li></ul><ul><li>Electrode holder with poor insulation </li></ul><ul><li>Poor contact of earth clamp </li></ul><ul><li>Spatter </li></ul><ul><li>Causes </li></ul><ul><li>Excessive arc energy </li></ul><ul><li>Excessive arc length </li></ul><ul><li>Damp electrodes </li></ul><ul><li>Arc blow </li></ul>
    123. 124. Steel Metallurgy <ul><li>Steel- Iron and carbon alloyed with other elements </li></ul><ul><li>Carbon- Strength, hardness, toughness, ductility </li></ul><ul><li>Manganese- Strength, hardenability </li></ul><ul><li>Silicon - Toughness </li></ul><ul><li>Molybdenum- Creep resistance, temper embrittlement </li></ul><ul><li>Chromium- Hardness, wear resistance, corrosion </li></ul><ul><li>Nickel - Ductility, strength, toughness </li></ul>
    124. 125. Steel Metallurgy <ul><li>Steel- Iron and carbon alloyed with other elements </li></ul>BCC FCC
    125. 126. Steel Metallurgy Low Stress Increased Stress Elastic Deformation Plastic Deformation
    126. 127. Heat Treatment <ul><li>Softening </li></ul><ul><li>Hardening </li></ul><ul><li>Tempering </li></ul><ul><li>Stress Relief </li></ul><ul><li>Post heat treatment performed to improve specific metallurgical or mechanical properties or stress relief </li></ul><ul><li>Controlled by </li></ul><ul><li>Heating rate </li></ul><ul><li>Temperature attained </li></ul><ul><li>Time at the elevated temperature </li></ul><ul><li>Cooling rate </li></ul>
    127. 128. Heat Treatment 900 850 800 750 700 Ar3 Ac1 Ac2 Ac3 Ar1 Ar2 1 2 Minutes to raise temperature by 10 C
    128. 129. Iron Carbide Diagram Ac3 Ac1 .2 .4 .6 .8 1 1.2 1.4 1.6 1.8 2 Carbon % 1000 900 800 700 600
    129. 130. Iron Carbide Diagram Ac3 Ac1 .2 .4 .6 .8 1 1.2 1.4 1.6 1.8 2 Carbon % 1000 900 800 700 600 Austenite Ferrite and Pearlite Pearlite and Cementite Austenite and Fe 3 C Austenite and Ferrite
    130. 131. Heat Treatment <ul><li>Hardening </li></ul><ul><li>Produce hard but brittle material </li></ul><ul><li>Heat to above transformation range </li></ul><ul><li>Cool very quickly ( quench ) in oil, water or brine </li></ul>
    131. 132. Heat Treatment <ul><li>Stress Relief </li></ul><ul><li>Relax stresses without significant changes in the metallurgical structure </li></ul><ul><li>Heat to 550-650 degrees C </li></ul><ul><li>Hold for 1 hour per 25mm thickness </li></ul><ul><li>Cool in air </li></ul>
    132. 133. Heat Treatment <ul><li>Full Annealing </li></ul><ul><li>Produces very soft low hardness material for machining or cold work </li></ul><ul><li>Heat to above 910 degrees C </li></ul><ul><li>Hold </li></ul><ul><li>Cool very slowly in furnace </li></ul><ul><li>Once reached 680 C , cool in air </li></ul>
    133. 134. Heat Treatment <ul><li>Sub Critical Annealing </li></ul><ul><li>Spheroidizing produces soft low hardness material cheaper than full anneal </li></ul><ul><li>Heat must not rise above 700 degrees C </li></ul><ul><li>Hold for recrystallisation to occur </li></ul><ul><li>Cool in air </li></ul>
    134. 135. Heat Treatment <ul><li>Normalising </li></ul><ul><li>Maintains and improves mechanical properties and modifies grain structure </li></ul><ul><li>Heat to above 910 degrees C </li></ul><ul><li>Hold </li></ul><ul><li>Cool in air </li></ul>
    135. 136. Nature and Origin of Defects <ul><li>Inherent </li></ul><ul><li>Processing </li></ul><ul><li>In Service </li></ul>
    136. 137. Heat Induced Defects <ul><li>Heat treatment cracks </li></ul><ul><li>Grinding cracks </li></ul><ul><li>Friction induced cracks </li></ul>
    137. 138. In Service Cracks <ul><li>Fatigue cracks </li></ul><ul><li>Stress corrosion cracks </li></ul><ul><li>Hydrogen induced cracks </li></ul>Hydrogen Cyclic stress Fatique crack

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