Residual Stresses in Friction Stir Welding

Preface to the Friction Stir Welding and Processing Book Series

Chapter 1. Introduction

1.1 Residual Stresses

1.2 Implication of RS

Chapter 2. A Brief Introduction to FSW

Chapter 3. RS in FSW Process

3.1 Materials Studied

3.2 RS in Aluminum Alloys

3.3 RS in Other Materials

3.4 Summary of RS in Ferrous and Nonferrous Materials

Chapter 4. Effect of RS on Properties

4.1 Mechanical Properties

4.2 Stress-Corrosion Cracking

Chapter 5. Parameters Affecting RS

5.1 The Effect of Tool Traverse Speed

5.2 The Effect of Tool Rotation Rate

5.3 Sample Size for Measurement of RS

Chapter 6. Characterization of RS

Chapter 7. Model for Understanding Residual Stress Development in Friction Stir-Welded Structures

7.1 Description of the Model

7.2 Computational Validation of the Model

7.3 Differences in RS in Fusion Welding and FSW

Chapter 8. Mitigation of RS During FSW

8.1 The Effect of Heat Sink (Thermal Tensioning) on the Residual Stress

8.2 The Effect of Mechanical Tensioning on the Residual Stress

8.3 The Effect of Roller Tensioning on the Residual Stress

8.4 The Effect of Laser and Shot Peening on RS

Chapter 9. Simulation of FSW for RS and Distortions

Chapter 10. Summary, Conclusions, and Future Direction

References

This book describes the fundamentals of residual stresses in friction stir welding and reviews the data reported for various materials. Residual stresses produced during manufacturing processes lead to distortion of structures. It is critical to understand and mitigate residual stresses. From the onset of friction stir welding, claims have been made about the lower magnitude of residual stresses. The lower residual stresses are partly due to lower peak temperature and shorter time at temperature during friction stir welding. A review of residual stresses that result from the friction stir process and strategies to mitigate it have been presented. Friction stir welding can be combined with additional in-situ and ex-situ manufacturing steps to lower the final residual stresses. Modeling of residual stresses highlights the relationship between clamping constraint and development of distortion. For many applications, management of residual stresses can be critical for qualification of component/structure.

• Reviews magnitude of residual stresses in various metals and alloys
• Discusses mitigation strategies for residual stresses during friction stir welding
• Covers fundamental origin of residual stresses and distortion