MECHANICAL WORKING

1. MECHANICAL WORKING ZUBAIR AHMAD UNITED GULF STEEL

2. Rolling(Hot/Cold) Permanent Deformation Mechanical Working = = Mechanical Working Is a permanent deformation to which metal is subjected to change its shape and/or properties.

3. Cooling Reheating Finishing Roughing Coiling • Grain Refinement • Precipitation • Austenite Decomposition • Accelerated Cooling • Precipitation • Phase transformation • Grain Refinement • Recrystallization • > 1200 °C • Austenitizing Slab Chemistry Chemistry (C, Mn, Ni, Cu, MAE) Thickness & Temperature Reduction

4. PSL2: • YS (min/max) • UTS (min/max) • YS/UTS • CVN • DWTT Strength Toughness Steel Mechanical Properties Ductility Sour Resistance • HIC • SSCC Weldability …etc • CEPcm

5. Chemistry Processing Parameters Microstructure Steel Mechanical Properties

6. 1- Meteoric Iron (5 – 30 % nickel) Limited 2- Telluric (Native) Iron (Grains or nodules of Iron in basalt that erupted through beds of coal) Rare 3- Man-made Ferrous Metals. (Use charcoal to reduce iron from its oxides) Fe2O3 + 3CO → 2Fe + 3 CO2 Basic Metallurgy وَأَنْزَلْنَا الْحَدِيدَ فِيهِ بَأْسٌ شَدِيدٌ وَمَنَافِعُ لِلنَّاسِ

7. Basic Metallurgy Iron is so important that primitive societies are measured by the point at which they learn how to refine iron and enter theiron age! Goldis for the mistress …. silverfor the maid Copperfor the craftsman cunning at his trade. "But Iron … Cold Iron … is master of them all !“ Rudyard Kipling, 1910

8. Basic Metallurgy Iron • Strong material • Easy to shape • Conduct heat and electricity • Unique magnetic properties • Iron is plentiful (5% of the Earth's crust) • Relatively easy to refine

9. Basic Metallurgy Iron ores are rocks that contain a high concentration of iron • Hematite - Fe2O3 - 70 % iron • Magnetite - Fe3O4 - 72 % iron • Limonite - Fe2O3 + H2O - 50 % to 66 % iron • Siderite - FeCO3 - 48 % iron Hematite

10. Grains Crystal Structure Basic Metallurgy

11. Atom Y Z X Basic Metallurgy Crystal Structure(Atomic Arrangement) Space Lattice: A collection of points that divided space into smaller sized segments. Unit Cell: A subdivision of the lattice that still retains the overall characteristics of the entire lattice.

12. Basic Metallurgy Formation of Polycrystalline Material Solid (Unit Cell) Liquid a b Grain Boundaries d c Grain Boundary: The zone of crystalline mismatch between adjacent grains. The lattice has different orientation on either side of the grain boundary a) Small crystalline nuclei b) Growth of Crystals c) Irregular grain shapes formed upon completion of solidification d) Final grain structure

13. Grain Boundary

14. 1540 oC BCC - Delta Iron (d) 1400 oC FCC - Gamma Iron (g) Temperature 910 oC BCC - Alpha Iron (a) Basic Metallurgy Atomic Packing in Iron (Allotropic)

15. Alpha & Delta Iron ( , ) a Total 2 Atoms/Unit Cell αLattice Parameter (a) = 0.287 nm δLattice Parameter (a) = 0.293 nm Basic Metallurgy Body Centered Cubic (BCC) Squared Packed Layer

16. Gamma Iron () a Total 4 Atoms/Unit Cell Lattice Parameter (a) = 0.359 nm Basic Metallurgy Face Centered Cubic (FCC) Close Packed Layer

17. Slip Distance Slip Distance Basic Metallurgy Effect of the Atomic Packing in Deformation Behavior Displacement High Dense Atomic Packing Displacement Low Dense Atomic Packing Slip occurs easily on closest packed plane (high atomic packing density) along the closest packed direction where the slip distance is minimum.

18. Basic Metallurgy Effect of the Atomic Packing in Deformation Behavior Smooth Surface Easy to slip with minimum power Example of closed Packed planes Uneven Surface Relatively high energy is required for limited slip Example of squared packed plans Rough Surface Extremely hard to slip Example of squared packed plans with high inter-atom spaces

19. Basic Metallurgy STEEL=IRON+ Alloying Elements ( C +Mn, Si,Ni, …) What is the difference between“STEEL”and“CAST IRON”? IRON+ < 2 % Carbon =STEEL IRON+ > 2 % Carbon =CAST IRON

20. Iron Carbon Phase Diagram (d+L) 1600 - 1540 Liquid (L) 1495 (d + g ) 0.18% 1400 - Delta Ferrite ( d ) 0.1% (g +L) 1200 - 1150 °C Austenite (g ) 2.1% 1000 - (g +Fe3C) 910 Temperature (oC) 800 - (a+g ) 727 °C 600 - Ferrite (a ) 400 - Ferrite + Pearlite 200 - 0 - 4.3% 4.0 0.8% 2.0 3.0 1.0 6.67 Hypoeutectoid Hypereutectic Hypereutectoid Hypoeutectic Steel Cast Iron Weight Percentage Carbon 0.5% Peritectic Eutectic Eutectoid Cementite (Fe3C)+ Pearlite

21. BCC - Delta Iron (d) FCC - Gamma Iron (g) BCC - Alpha Iron (a) Basic Metallurgy Atomic Packing in Iron (Allotropic)

22. Ferrite Cementite (d+L) 1600 - 1540 Liquid (L) 1495 (d + g ) 1400 - Peritectic (g +L) Delta Ferrite ( d ) 1200 - 1150 °C Austenite (g ) Temperature (oC) 1000 - (g +Fe3C) 910 800 - (a+g ) 727 °C Eutectoid 600 - Ferrite (a ) 400 - Ferrite + Pearlite Cementite (Fe3C)+ Pearlite 200 - 0 - 0.8% 2.0 1.0 Weight Percentage Carbon Basic Metallurgy 0. 8% C 0. 5% C ~0% C 0.2% C 0. 7% C 0.35% C 1.2% C

23. Basic Metallurgy Fundamental Mechanical Properties • Strength: • Ability to withstand loads (Tensile & Compressive Strength) • Ductility: • Ability to deform under tensile loads without rupture • Bending Ability • Ability to bend without Fracture • Toughness • Ability to absorb energy in shock loading (Impact Strength) • Hardness • Resistance to penetration • Weldability • Ability to be welded without cracking

24. Basic Metallurgy Effect of Alloying Elements Carbon (C):  Strength & Hardness  Ductility, Malleability & Weldability Silicon (Si): De-oxidizer,  Strength, Hardenability & Impact Strength Manganese (Mn): De-oxidizer,  Strength & Toughness  Hardenability Strong De-oxidizer,  Grain Refinement  Strength & Toughness Aluminum (Al): Sulfur (S): Harmful  Ductility, Weldability Strength & Impact Strength  Grain Refinement  Strength, Hardenability & Toughness MAE (V, Ti & Nb):

25. Basic Metallurgy Stress – Vs - Strain Stress: Force per unit area Measuring the internal resistance of the body. s = F/Ao Strain: Unit deformation Measuring the change in dimensions of the body e = (L1 – Lo)/Lo Force (F) F L1 Lo L1

26. S B Y Stress P O Strain Elastic Def. Plastic Deformation Basic Metallurgy Stress – Vs - Strain P: Elastic Limit Y: Yield Point S: Max. Load Value B: Breaking Point

27. Basic Metallurgy Elastic & Plastic Deformation Elastic Deformation: Deformation of a material that recovered when the applied load is removed. This type of deformation involves stretching of the bonds without permanent atomic displacement. Plastic Deformation: Permanent deformationof a materialthat is not recovered when the applied load is removed. This Type of deformation involves breaking of a limited number of atomic bonds.

28. Basic Metallurgy Microstructural Defects Theoretical yield strength predicted for perfect crystals is much greater than the measured strength. The existence of defects explains the difference. Which is easier to cut?

29. Basic Metallurgy Braking all atomic bonds at once requires grater energy in perfect crystal

30. Basic Metallurgy Microstructural Defects 1)Point defects:a) vacancies, b) interstitial atoms, c) small substitional atoms, d) large substitional atoms, … etc. 2) Surface defects:Imperfections, such as grain boundaries, that form a two-dimensional plane within the crystal.

31. Basic Metallurgy Microstructural Defects 3) Line defects:dislocations (edge, screw, mixed) • Dislocation:A line imperfection in the lattice or crystalline material They are typically introduced into the lattice during solidification of the material or when the material is deformed. • Movement of dislocations helps to explain how materials deform. Interface with movement of dislocations helps explain how materials are strengthened.

32. Basic Metallurgy Motion of Dislocation When a shear stress is applied to the dislocation in (a), the atoms displaced, causing the dislocation to move one step (Burger’s vector) in the slip (b). Continued movement of the dislocation eventually creates a step (deformation) direction (C)

33. Thank You