Duplex Stainless Steels

Duplex Stainless Steels (DSSs) are chromium-nickel-molybdenum-iron
alloys that are usually in proportions optimized for equalizing the
volume fractions of austenite and ferrite. Due to their
ferritic-austenitic microstructure, they possess a higher
mechanical strength and a better corrosion resistance than standard
austenitic steels. This type of steel is now increasing its
application and market field due to its very good properties and
relatively low cost.

This book is a review of the most recent progress achieved in
the last 10 years on microstructure, corrosion resistance and
mechanical strength properties, as well as applications, due to the
development of new grades. Special attention will be given to
fatigue and fracture behavior and to proposed models to account for
mechanical behavior. Each subject will be developed in chapters
written by experts recognized around the international industrial
and scientific communities.

The use of duplex stainless steels has grown rapidly in the last
10 years, particularly in the oil and gas industry, chemical
tankers, pulp and paper as well as the chemical industry. In all
these examples, topics like welding, corrosion resistance and
mechanical strength properties (mainly in the fatigue domain) are
crucial. Therefore, the update of welding and corrosion properties
and the introduction of topics like texture effects, fatigue and
fracture strength properties, and mechanical behavior modeling give
this book specific focus and character.

Auteur

Suzanne Degallaix is Professor at the Laboratoire de Mécanique de Lille, Ecole Centrale de Lille, FRANCE. Iris Alvarez-Armas is Director of Research at the Instituto de Física Rosario, Universidad Nacional de Rosario, ARGENTINA.

Résumé
Duplex Stainless Steels (DSSs) are chromium-nickel-molybdenum-iron alloys that are usually in proportions optimized for equalizing the volume fractions of austenite and ferrite. Due to their ferritic-austenitic microstructure, they possess a higher mechanical strength and a better corrosion resistance than standard austenitic steels. This type of steel is now increasing its application and market field due to its very good properties and relatively low cost. This book is a review of the most recent progress achieved in the last 10 years on microstructure, corrosion resistance and mechanical strength properties, as well as applications, due to the development of new grades. Special attention will be given to fatigue and fracture behavior and to proposed models to account for mechanical behavior. Each subject will be developed in chapters written by experts recognized around the international industrial and scientific communities.

The use of duplex stainless steels has grown rapidly in the last 10 years, particularly in the oil and gas industry, chemical tankers, pulp and paper as well as the chemical industry. In all these examples, topics like welding, corrosion resistance and mechanical strength properties (mainly in the fatigue domain) are crucial. Therefore, the update of welding and corrosion properties and the introduction of topics like texture effects, fatigue and fracture strength properties, and mechanical behavior modeling give this book specific focus and character.

Contenu

Preface xiii

Chapter 1. Process: Hot Workability 1
Isabel GUTIERREZ and Amaia IZA-MENDIA

1.1. Introduction 1

1.2. As-cast microstructure 1

1.3. Microstructural evolution during hot working 4

1.4. Mechanical behavior under hot working 16

1.5. Static softening 28

1.6. Hot workability 31

1.7. Conclusions 39

1.8. Acknowledgments 39

1.9. References 39

Chapter 2. Corrosion Resistance Properties 47
Jacques CHARLES

2.1. Introduction 47

2.2. The duplex grades and pitting resistance equivalent numbers 48

2.3. Some fundamentals concerning stainless steel corrosion resistance 50

2.4. The different forms of corrosion 60

2.5. Some complex corrosion behaviors encountered in industrial applications 100

2.6. Conclusions 111

2.7. References 111

Chapter 3. Phase Transformation and Microstructure 115
Angelo Fernando PADILHA and Ronald Lesley PLAUT

3.1. Introduction 115

3.2. Phase diagrams and typical phases 117

3.3. Solidification 120

3.4. Austenite precipitation 121

3.5. Phase changes occurring below 1,000°C 123

3.6. Cold working and annealing 132

3.7. Final remarks 134

3.8. References 135

Chapter 4. Welding Processes, Microstructural Evolution and Final Properties of Duplex and Superduplex Stainless Steels 141
Franco BONOLLO, Alberto TIZIANI and Paolo FERRO

4.1. Introduction 141

4.2. Ï-ferrite Ïnaustenite transformation 142

4.3. Secondary and intermetallic phases precipitation during welding processes 145

4.4. Welding processes for DSS and SDSS 147

4.5. Final remarks 155

4.6. References 155

Chapter 5. Thermal Embrittlement of Cast Duplex Stainless Steels: Observations and Modeling 161
Andre PINEAU and Jacques BESSON

5.1. Introduction 161

5.2. Composition, elaboration, microstructure, and mechanical properties 163

5.3. Thermal embrittlement of the ferrite phase in DSS 170

5.4. Materials investigated and embrittlement heat treatments 181

5.5. Damage and rupture 186

5.6. Scale effect and scatter 189

5.7. Modeling of rupture 192

5.8. Conclusion 201

5.9. References 201

Chapter 6. Low-Cycle Fatigue at Room Temperature 209
Iris ALVAREZ-ARMAS

6.1. Introduction 209

6.2. Cyclic hardening/softening process 210

6.3. Uniaxial cyclic plasticity in DSSs 219

6.4. Final remarks 236

6.5. Acknowledgments 237

6.6. References 237

Chapter 7. Multiaxial Low-Cycle Fatigue Behavior at Room Temperature 241
Suzanne DEGALLAIX-MOREUIL

7.1. Introduction 241

7.2. Multiaxial LCF introduction 242

7.3. Biaxial LCF of a DSS type 25-07 248

7.4. Conclusions 270

7.5. Acknowledgments 270

7.6. References 270

Chapter 8. Partition of Cyclic Plasticity in the 25Cr-7Ni-0.25N Duplex Stainless Steel Investigated by Atomic Force Microscopy 275
Jean-Bernard VOGT, Daniel SALAZAR and Ingrid PRORIOL SERRE

8.1. Introduction 275

8.2. Material 277

8.3. Experimental procedure 278

8.4. Cyclic behavior at a low strain range 280

8.5. Cyclic behavior at a high strain range 289

8.6. Conclusions 300

8.7. References 300

Chapter 9. Macro- and Micromodeling of the Monotonic and Cyclic Mechanical Behavior of a Forged DSS 303
Veronique AUBIN and Pierre EVRARD

9.1. Introduction 303

9.2. Macroscopic modeling of the mechanical behavior 304

9.3. Micromechanical modeling 318

9.4. General conclusion 332

9.5. References 334 Chapter 10. Low-Cycle Fatigue at Intermediate Temperatures 339
Alberto F. ...