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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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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


Classification of sheet steels
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


Steel Melting and Casting

C+O=CO2

Alloy

Additions

Making, Shaping & Treating of Steel,

USS, 1964


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


Steel refining - IF Steels

Making, Shaping & Treating of Steel,

USS, 1964


Classification of sheet steels1
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


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


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


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?


Classification of sheet steels2
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


Cold Rolling and Annealing

Cold Worked

Structure

Recovery

1

2

3

Recrystallization

4


Classification of sheet steels3
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


Transformation Hardened Steels

H2O

Martensitic Structure

H2O


Tempering

1

2

3

4


Spot Weldability

(Production of Welds Fit for Service)

Process Variables

(Things Manufacturers Control)

Material Variables

(Things Steel Makers Control)

Module 3

Module 4


Homework

Assignment 2


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