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Agenda

Overview of Process

Discussion of Caster in detail

Defects and preventative measures Discussion of inspection

procedures

UT ASTM A578

Questions

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Steelmaking Process

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Melt Shop: Scrap

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Melt Shop: EAF

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Tapping EAF

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Melt Shop: Twin LMF

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Melt Shop: LMF

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Meltshop: Casting

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Slab

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Roll Mill: Reheat Furnace

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Roll Mill: Rolling Mill

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Roll Mill: Hot Shear

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Roll Mill: Leveler

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Cooling Bed

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Roll Mill: Cold Shear

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Mechanical Testing Lab

Impact Testing Tensile Testing

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Product Traceability

Die Stamping Paint Marking

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On-Site MetallurgicalFacilities

Scanning ElectronMicroscope Electrolytic Macro-etch

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Shipping

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Discussion of Internalimperfections

Segregation

Voids

Streaks Laminations

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Slab Defects

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Segregation

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Solidification

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Solidification

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Grain Structure

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Ways to minimizesegregation

Lower carbon

Control superheat

Control bulging Lower cast speed to be able to do

more soft reduction

Lower Hydrogen Minimize Chemistry

Higher reduction ratios

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What is Soft Reduction?

Final point ofsolidificationmoves down

withincreasingcasting speed

Squeeze atfinal point ofsolidification

Localized Linear

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Superheat Monitoring

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Voids and Laminations

Caused by similar factors assegregation

Superheat

Dissolved gases

Misalignment in machine

Steel shrinks as it solidifies.

Voids considered normal

Laminations not considerednormal.

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Radial Streaks

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W i i i

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Ways to minimizestreaking

Excellent roll alignment

Control bulging

Lower Hydrogen Minimize Chemistry

Higher reduction ratios to heal any

streaks Uniform cooling

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Rolling process

Elongated Grains

Very high strength

and low ductility

Equiaxed Grains

Rolling Direction

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Nucor-Hertford Inspection of Bridge Grades

All weathering grades > 1.25, each end for 24

All grade 50 > 1.50, each end for 24

All grade 36 > 1.50, each end for 24

Nucor In-House Quality Checks

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Industry Standard ASTM A578 or A435, only when ordered

Flaw size permitted, up to 3 diameter with total loss of back

reflection

Nucor Standard Rejection criteria is more stringent than ASTM

Nucor vs Industry Standard for InternalSoundness

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Level Criteria Bridge Other Structural

Level 1 Less than 10% Screen Height Pass Pass

Level 2 10%-30% Screen Height Pass Pass

Level 3 30%-50% Screen Height Pass Pass

Level 4 50% Screen HeightIndication Less than 1

Fail Pass

Level 5 50% Screen Height

Indication Greater than 1

Fail Fail

Nucor-Hertford UT Acceptance Criteria

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Typical UT Indication on a 2 plate

0

20

40

60

80

100

0 0.5 1 1.5 2

ScreenHeight(%)

Distance (in.)

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ASTM UT Reject at Mid-Thickness of 2 Plate

0

20

40

60

80

100

0 0.5 1 1.5 2

ScreenHeight(%)

Distance (in.)

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Nucor Hertford UT Rejection

0

20

40

60

80

100

0 0.5 1 1.5 2

ScreenHeight(%)

Distance (in.)

M Cl

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Mannesman Class 1

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Class 2

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Class 5

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Short and Long term plans

Short term

Machine alignment

Increased inspection when a problem

is found Reduced cast speed

Degassing

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Speed Restrictions

Since 2008, Nucor has 62 gradesthat have speed restrictions to helpwith centerline and porosity(35% of

our grades and mix). Speed restriction cause solidification

higher in the machine and allows for

more time to perform soft reduction 60% of all greater than 1 material has

speed restrictions.

95% of all greater than 2 material has

speed restrictions.

Work done on improving

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Work done on improvingsurface quality

2010 revised our soft reduction tables

2011 set up routine macro sampling

Added personnel to do this

Helps identify problems in machinesooner

2011 Improved superheat control

2012 Installed Degasser Started up July of 2012

Now degassing 20-25% of our product

Results of Quality

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Results of QualityImprovements

YearInternal

Soundness Porosity Total

2008 0.21% 0.04% 0.25%

2009 0.31% 0.01% 0.32%

2010 0.42% 0.12% 0.55%

2011 0.24% 0.04% 0.28%

2012 0.17% 0.02% 0.18%

* Results are summary across all gauges/grades and includenon degassed material.

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Long term plans

Long term

Replace segments to improve coolingpatterns

Current segments leave non-uniformsoldification patterns

Danieli new anti-bulging program

Investigating on-line UT