Uncoated Plain Carbon SteelsSteel Production
Steel Production
Lesson ObjectivesWhen 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 Activities1. Look up Keywords2. View Slides; 3. Read Notes, 4. Listen to lecture5. Do on-line
workbook6. Do homework
KeywordsHot 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
Steel Type
Interstitial-Free Steel
Mild Steel
Rephosphorized Steel
PPN Hardened/GrainRefined 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
TS. < 30 ksiElongation: 50%
TS. < 40 ksiElongation: 30%
TS. > 40 ksiElongation > 20%
TS.: 50 - 80 ksi
TS.: 50 - 150 ksi
Mechanical PropertiesHot Rolled
ColdRolled
RecoveryAnnealed
Steel Melting and Casting
Making, Shaping & Treating of Steel,USS, 1964
C+O=CO2
Alloy Additions
A Few Melting Practice ProblemsWhich 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
Steel Type
Interstitial-Free Steel
Mild Steel
Rephosphorized Steel
PPN Hardened/GrainRefined 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
TS. < 30 ksiElongation: 50%
TS. < 40 ksiElongation: 30%
TS. > 40 ksiElongation > 20%
TS.: 50 - 80 ksi
TS.: 50 - 150 ksi
Mechanical PropertiesHot Rolled
ColdRolled
RecoveryAnnealed
Hot Rolling of Strip
Dynamic RecrystallizationFollowed by Grain Growth
Large GrainAustenite
Large GrainAustenite
TransformsFerrite/Pearlite
TIME
TEM
PE
RA
TUR
E
Martensite
Ferrite +Pearlite
Fine = Higher Strength
Coarse = Lower Strength
CQ, DQ & IF Steels
Rephosphorized Steel
Controlled Hot Rolled Strip Processing
Dynamic RecrystallizationPinned Grain Boundaries
Grain Size(fine)
Str
eng
th
ppt
Grain Refinement
HSLA Steels
Solid Solid SolutionSolution(Rephos)(Rephos)HSLA
SteelDual Phase Steel
TRIPSteel
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
Steel Type
Interstitial-Free Steel
Mild Steel
Rephosphorized Steel
PPN Hardened/GrainRefined 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
TS. < 30 ksiElongation: 50%
TS. < 40 ksiElongation: 30%
TS. > 40 ksiElongation > 20%
TS.: 50 - 80 ksi
TS.: 50 - 150 ksi
Mechanical PropertiesHot Rolled
ColdRolled
RecoveryAnnealed
Cold Rolling and Annealing
Str
eng
th
% Cold Reduction
Str
en
gth
Anneal Temperature
Recovery
Recrystallization
1
2
3
4
Cold Worked Structure
Classification of Sheet Steels
Steel Type
Interstitial-Free Steel
Mild Steel
Rephosphorized Steel
PPN Hardened/GrainRefined 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
TS. < 30 ksiElongation: 50%
TS. < 40 ksiElongation: 30%
TS. > 40 ksiElongation > 20%
TS.: 50 - 80 ksi
TS.: 50 - 150 ksi
Mechanical PropertiesHot Rolled
ColdRolled
RecoveryAnnealed
Transformation Hardened Steels
H2O
H2O
TIME
TEM
PE
RA
TUR
E
Martensite
Ferrite +Pearlite
Martensitic Structure
% Carbon
Har
dnes
s
Tempering
Tempering Temperature - 1 hr.
Hard
ness
12
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
Assignment 2