Transcript No Slide Title

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
1. Look up Keywords
2. View Slides;
3. Read Notes,
4. Listen to lecture
5. Do on-line
workbook
6. 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
Mechanical Properties
Hot Rolled
Steel Type
Chemistry
Interstitial-Free Steel
TS. < 30 ksi
C < 0.01%
Boron & Ti additions Elongation: 50%
Mild Steel
C: 0.02 - 0.08%
Mn: 0.3%
TS. < 40 ksi
Elongation: 30%
Rephosphorized Steel
P: 0.07%
TS. > 40 ksi
Elongation > 20%
PPN Hardened/Grain
Refined Steel (HSLA)
Cb & V: 0.02%
TS.: 50 - 80 ksi
Transformation
Hardened Steel
TS.: 50 - 150 ksi
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 Steels
Mechanical Properties
Hot Rolled
Steel Type
Chemistry
Interstitial-Free Steel
TS. < 30 ksi
C < 0.01%
Boron & Ti additions Elongation: 50%
Mild Steel
C: 0.02 - 0.08%
Mn: 0.3%
TS. < 40 ksi
Elongation: 30%
Rephosphorized Steel
P: 0.07%
TS. > 40 ksi
Elongation > 20%
PPN Hardened/Grain
Refined Steel (HSLA)
Cb & V: 0.02%
TS.: 50 - 80 ksi
Transformation
Hardened Steel
TS.: 50 - 150 ksi
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 Transforms
Austenite
Large Grain
Austenite
Ferrite/Pearlite
TEMPERATURE
CQ, DQ &
IF Steels
Coarse = Lower Strength
Ferrite +
Pearlite
Fine = Higher Strength
Martensite
TIME
Rephosphorized
Steel
Controlled Hot Rolled Strip Processing
Dynamic Recrystallization
Pinned Grain Boundaries
HSLA
Steel
Dual
Phase
Steel
Strength
HSLA Steels
Solid
Solution
(Rephos)
ppt
Grain Refinement
Grain Size
TRIP
Steel
(f ine)
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 Steels
Mechanical Properties
Hot Rolled
Steel Type
Chemistry
Interstitial-Free Steel
TS. < 30 ksi
C < 0.01%
Boron & Ti additions Elongation: 50%
Mild Steel
C: 0.02 - 0.08%
Mn: 0.3%
TS. < 40 ksi
Elongation: 30%
Rephosphorized Steel
P: 0.07%
TS. > 40 ksi
Elongation > 20%
PPN Hardened/Grain
Refined Steel (HSLA)
Cb & V: 0.02%
TS.: 50 - 80 ksi
Transformation
Hardened Steel
TS.: 50 - 150 ksi
C: 0.05 - 0.15%
Mn: 0.5 - 1.5 % + Si
Cold
Rolled
Recovery
Annealed
Cold Rolling and Annealing
Strength
Cold Worked
Structure
% Cold Reduction
Recovery
Strength
1
2
3
4
Anneal Temperature
Recrystallization
Classification of Sheet Steels
Mechanical Properties
Hot Rolled
Steel Type
Chemistry
Interstitial-Free Steel
TS. < 30 ksi
C < 0.01%
Boron & Ti additions Elongation: 50%
Mild Steel
C: 0.02 - 0.08%
Mn: 0.3%
TS. < 40 ksi
Elongation: 30%
Rephosphorized Steel
P: 0.07%
TS. > 40 ksi
Elongation > 20%
PPN Hardened/Grain
Refined Steel (HSLA)
Cb & V: 0.02%
TS.: 50 - 80 ksi
Transformation
Hardened Steel
TS.: 50 - 150 ksi
C: 0.05 - 0.15%
Mn: 0.5 - 1.5 % + Si
Cold
Rolled
Recovery
Annealed
Transformation Hardened Steels
H2 O
Martensitic Structure
Hardness
TEMPERATURE
H 2O
% Carbon
Ferrite +
Pearlite
Martensite
TIME
Tempering
1
Hardness
2
3
4
Tempering Temperature - 1 hr.
Spot Weldability
(Production of Welds Fit for Service)
Process Variables
Material Variables
(Things Manufacturers Control)
(Things Steel Makers Control)
Module 3
Module 4
Assignment 2