benefits of thermodynamic simulations in an industrial...

Aachen, September 6th 2012

Benefits of thermodynamic simulations

in an industrial setting

F. Hagemann, B. Maas, B. Springub

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Benefits of thermodynamic simulations in an industrial setting

Agenda

Introduction

Salzgitter AG

Salzgitter Mannesmann Forschung GmbH (SZMF)

Thermo-Calc use modes

Examples

Liquidus temperature calculation for casting temperature control

Continuous casting:

Solidification interval modification

Identification of peritectic transformation

Hot rolling: Post mortem analysis of martensite formation

Summary and conclusion

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Agenda

Introduction

Salzgitter AG



Examples


Continuous casting:




Summary and Conclusion

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• Crude steel production: 6.9 million tons; trading volume: 6.8 million tons

• Among the top 3 producers of beverage filling und packaging machinery

Salzgitter AG: Global Presence

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Salzgitter AG: Diversified product portfolio

Line pipes

Precision tubes

Stainless tubes

Stockholding trading

International trading

Strip products

Heavy plates

Sections

Engineering services

Logistics

Injection molding machinery Beverage filling plants

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Steel

and

Technology

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Salzgitter AG

Salzgitter AG (Holding)

Salzgitter Mannesmann GmbH – Intermediate Holding Company

SteelSalzgitter Stahl GmbH

Trading ServicesTubesMannesmannröhren-

Werke GmbH

TechnologyKlöckner-Werke AG

Salzgitter Flachstahl Europipe (50%)Salzgitter Mannesmann

Handel GruppeKHS-Gruppe DEUMU

Ilsenburger GrobblechSalzgitter Mannesmann

LinepipeUniversal

Klöckner DESMA

Elastomertechnik

Salzgitter Service

und Technik

Peiner TrägerSalzgitter Mannesmann

PrecisionHövelmann & Lueg

Klöckner DESMA

Schuhmaschinen

Verkehrsbetriebe

Peine-Salzgitter

HSP Hoesch Spundwand

und Profil

Salzgitter Mannesmann

Stainless Tubes

Klöckner Hänsel

ProcessingTelcat

Salzgitter BauelementeSalzgitter Mannesmann

GroßrohrGESIS

Salzgitter EuroplatinenHüttenwerke Krupp

Mannesmann (30%)Hansaport (51%)


Grobblech


Forschung

Salzgitter Automotive

Engineering

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Crude steel production 2008: 5.3 mt Segment Sales: € 4.3 billion

Shipments 2008: 5.4 mt External Sales: € 3.0 billion

Salzgitter AG: Steel Division – Overview

Steel Division

Heavy plate Sections Processing Strip steel

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• largest subsidiary

• integrated iron & steel works

• hot-rolled strips and sheets• cold-rolled sheets

• surface-finished products

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Materials and process development

Metallographic and metallurgicmaterials characterization

Process analysis and numericalsimulation

Materials development

DSC/BCTMaterials and processes

NDT

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Agenda

Introduction

Salzgitter AG



Examples


Continuous casting:





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How do we use Thermo-Calc?

TCS

TCW

...and our own ‚automatisation‘ in the form of Perl scripts:

• Set of chemical compositions

(csv file: C, Si, Mn, ....)

• Type of calculation

(Tliq, equilib. phase fractions, ...)

Input:

1. Parse input

2. Write tcm scripts

• based on a set of templates

• one script for each chem. comp.

• templates for different type of calc.

3. Run tcs with scripts

4. Parse output, check for errors,

extract results

Perl-Scripts:

csv file:

• Chemical composition

• Calculation result

(Tliq, equilib. phase fractions, ...)

• Error condition

Output:

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Agenda

Introduction

Salzgitter AG



Examples


Continuous casting:





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Steel production – A very brief overview

Reheating

Hot Rolling

Cold RollingSkin Passing

Surface Finishing

Steel works

Pig Iron

Coke

Iron Ore

Charging

Hot Air

Blast Furnace

Roughing

Annealing

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Calculation of liquidus temperatures (1)

converter

arrival ladle treatm.

finish ladle treatm.

cont. casting

liquidus temperature

time

tem

pe

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Approach by Schürmann (Schürmann et al., steel research 68, 1997):

Calculation of carbon equivalence factors

xi from liquidus lines of binary Fe-Xi systems

Model ∆xi as a second order polynomial

Fit ai,bi to Fe-Xi binary systems

Calculate total carbon equivalence factor:

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Approach by Schürmann (Schürmann et al., steel research 68, 1997):

Calculation of carbon equivalence factors

xi from liquidus lines of binary Fe-Xi systems

Use the Fe-C system to calculate Tliq

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Original works by Schürmann et al.

Coefficients a and bLiquidus lines

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Our modifications:

Use Thermo-Calc to calculate liquidus lines

Fit third order (instead of second order) polynomials to those

Include more elements (e.g. B, Ti)

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Cr-Stahl C Mn Si Cr Ni Mo V TLiquid, Exp TLiquid, TC TLiquid, Modell

wt. % 0,310 0,935 0,271 3,640 0,654 1,110 0,312 1491,8°C 1493,6°C 1493,3°C

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1400 1420 1440 1460 1480 1500 1520 1540

Temperatur [°C]

Ph

ase

na

nte

il [-]

Liquid

Ferrit

Austenit

TLiquidus=1493.6°C

TSolidus=1440.1°C

TSolidus =1478,1°CTLiquidus =1491,8°C

C Mn Si Cr Ni TLiquid, Exp TLiquid, Schürmann TLiquid, Modell

0,25% 1,43% 0,28% 0,25% 0,19% 1505°C 1504,7°C 1505,4°C

Literature example (Schürmann)

High Cr-steel

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Comparison: Old empirical model vs. new Schürmann based

Results:

Process stability increased through better Tliq prediction

(avoid ladle freezing)

Unified description for all produced steel grades (instead of

separate models, e.g. specific to carbon steels)

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Reheating

Hot Rolling


Surface finishing

Steel works

Pig Iron

Coke

Iron Ore

Charging

Hot Air

Blast Furnace

Roughing

Annealing

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Continuous casting

Various questions: – often as a result of surface defects (e.g. sliver defects)– often routine tasks

Examples:

Adjustment of the solidifaction interval by changing thesteel composition

Check for peritectic solidification

Identification of possible precipates during strand coolingthat may lead to embrittlement

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Reheating

Hot Rolling


Surface finishing

Steel works

Pig Iron

Coke

Iron Ore

Charging

Hot Air

Blast Furnace

Roughing

Annealing

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4 reheating furnaces

water descaling

sizing press

roughing train

cropping shear

3 down coilersfinishing train7 stands

slab thickness = 250mmsheet thickness = 1.5…25mmsheet width = 900…2000mmcapacity = approx. 3.5 Mt/yearProduct range:Complex phase steels, ULC, HSLA, carbon steels up to C75, steels for line pipes, tempering steels

Hot strip mill

run-out table (ROT)

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Post mortem analysis of martensite formation (1)

wt. %

C 0.05

Si 0.3

Mn 1.8

Cr + Mo 0.4

Ti + Nb 0.11

X80, 18.9 mm

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Low CT


wt. %

C 0.05

Si 0.3

Mn 1.8

Cr + Mo 0.4

Ti + Nb 0.11

X80, 18.9 mm

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wt. %

C 0.05

Si 0.3

Mn 1.8

Cr + Mo 0.4

Ti + Nb 0.11

X80, 18.9 mm

High CT

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wt. %

C 0.05

Si 0.3

Mn 1.8

Cr + Mo 0.4

Ti + Nb 0.11

High CT: about 20% martensiteLow CT: no martensite

X80, 18.9 mm

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X80, 18.9 mm45% of ferrite

Massive carbon

enrichment in austenite

⇒ Stabilization of

austenite

⇒ Martensite formationduring coil cooling


Small amount of ferrite

No carbon enrichment

in austenite

⇒ Formation of bainite

wt. %

C 0.05

Si 0.3

Mn 1.8

Cr + Mo 0.4

Ti + Nb 0.11

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Summary and conclusion

Thermo-Calc and Dictra - Useful tools for us:

Liquidus temperatures

Solidification intervals

Peritectic transformation

Phase transformation and carbon enrichment on the ROT

...

Major benefits in supporting process and material development

by providing quick estimates without materials’ synthesis or a

trial production run.

Experimental validation and verification of results

remains a top priority.

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Thank you for your kind attention.

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