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Uncoated Plain Carbon Steels Steel Production

Uncoated Plain Carbon Steels Steel Production. Steel Production. Lesson Objectives When you finish this lesson you will understand: The principles of basic steel making and casting The principles of steel rolling Factors effecting steel properties. Learning Activities Look up Keywords

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Uncoated Plain Carbon Steels Steel Production

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  1. Uncoated Plain Carbon Steels Steel Production

  2. Steel Production • Lesson Objectives • When you finish this lesson you will understand: • The principles of basic steel making and casting • The principles of steel rolling • Factors effecting steel properties • Learning Activities • Look up Keywords • View Slides; • Read Notes, • Listen to lecture • Do on-line workbook • Do homework Keywords Hot Rolling, Cold Rolling, Interstitial Free Steels, Mild Steel, Rephosphorized Steel, High Strength Low Alloy Steels, Transformation Hardened Steels, Recovery Annealed Steels, Basic Oxygen Steel Making, Casting, Continuous Casting, Vacuum Arc Remelting, Dynamic Recrystallization, Grain Refinement, Tempering

  3. Classification of Sheet Steels Mechanical Properties Hot Rolled TS. < 30 ksi Elongation: 50% TS. < 40 ksi Elongation: 30% TS. > 40 ksi Elongation > 20% TS.: 50 - 80 ksi TS.: 50 - 150 ksi Steel Type Interstitial-Free Steel Mild Steel Rephosphorized Steel PPN Hardened/Grain Refined Steel (HSLA) Transformation Hardened Steel Chemistry C < 0.01% Boron & Ti additions C: 0.02 - 0.08% Mn: 0.3% P: 0.07% Cb & V: 0.02% C: 0.05 - 0.15% Mn: 0.5 - 1.5 % + Si Cold Rolled Recovery Annealed

  4. Steel Melting and Casting C+O=CO2 Alloy Additions Making, Shaping & Treating of Steel, USS, 1964

  5. A Few Melting Practice Problems Which Can Result in Weld Problems • Porosity • Loss of Intended Alloy Addition • Intermetallic Inclusions • Stringers or Banded Material • Poor Ingot Surface Carried Over to Strip

  6. Steel refining - IF Steels Making, Shaping & Treating of Steel, USS, 1964

  7. Classification of Sheet Steels Mechanical Properties Hot Rolled TS. < 30 ksi Elongation: 50% TS. < 40 ksi Elongation: 30% TS. > 40 ksi Elongation > 20% TS.: 50 - 80 ksi TS.: 50 - 150 ksi Steel Type Interstitial-Free Steel Mild Steel Rephosphorized Steel PPN Hardened/Grain Refined Steel (HSLA) Transformation Hardened Steel Chemistry C < 0.01% Boron & Ti additions C: 0.02 - 0.08% Mn: 0.3% P: 0.07% Cb & V: 0.02% C: 0.05 - 0.15% Mn: 0.5 - 1.5 % + Si Cold Rolled Recovery Annealed

  8. Hot Rolling of Strip Dynamic Recrystallization Followed by Grain Growth Large Grain Austenite Transforms Large Grain Austenite Ferrite/Pearlite CQ, DQ & IF Steels Coarse = Lower Strength Fine = Higher Strength Rephosphorized Steel

  9. Controlled Hot Rolled Strip Processing Dynamic Recrystallization Pinned Grain Boundaries HSLA Steels ppt Solid Solution (Rephos) Dual Phase Steel HSLA Steel Grain Refinement TRIP Steel

  10. Questions? • Turn to the person sitting next to you and discuss (1 min.): • The particles that pin the grain boundaries during hot rolling are carbides and carbonitrides of niobium, vanadium and titanium. These each have their own dissolution temperature where they go back into solution in the steel. What happens if the temperature of the strip is just below this dissolution temperature (I.e. the particle have precipitated and are available for pinning grains) just before the strip goes through a hot rolling mill? Why might steel makers select a combination of these elements for their chemistry formulation?

  11. Classification of Sheet Steels Mechanical Properties Hot Rolled TS. < 30 ksi Elongation: 50% TS. < 40 ksi Elongation: 30% TS. > 40 ksi Elongation > 20% TS.: 50 - 80 ksi TS.: 50 - 150 ksi Steel Type Interstitial-Free Steel Mild Steel Rephosphorized Steel PPN Hardened/Grain Refined Steel (HSLA) Transformation Hardened Steel Chemistry C < 0.01% Boron & Ti additions C: 0.02 - 0.08% Mn: 0.3% P: 0.07% Cb & V: 0.02% C: 0.05 - 0.15% Mn: 0.5 - 1.5 % + Si Cold Rolled Recovery Annealed

  12. Cold Rolling and Annealing Cold Worked Structure Recovery 1 2 3 Recrystallization 4

  13. Classification of Sheet Steels Mechanical Properties Hot Rolled TS. < 30 ksi Elongation: 50% TS. < 40 ksi Elongation: 30% TS. > 40 ksi Elongation > 20% TS.: 50 - 80 ksi TS.: 50 - 150 ksi Steel Type Interstitial-Free Steel Mild Steel Rephosphorized Steel PPN Hardened/Grain Refined Steel (HSLA) Transformation Hardened Steel Chemistry C < 0.01% Boron & Ti additions C: 0.02 - 0.08% Mn: 0.3% P: 0.07% Cb & V: 0.02% C: 0.05 - 0.15% Mn: 0.5 - 1.5 % + Si Cold Rolled Recovery Annealed

  14. Transformation Hardened Steels H2O Martensitic Structure H2O

  15. Tempering 1 2 3 4

  16. Spot Weldability (Production of Welds Fit for Service) Process Variables (Things Manufacturers Control) Material Variables (Things Steel Makers Control) Module 3 Module 4

  17. Homework Assignment 2

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