Dislocation Strengthening

1. Dislocation Strengthening: Introduction
2. Work Hardening
3. Plastic Flow
4. Yield Point and Lüder's Strain I
5. Yield Point and Lüder's Strain II
6. Introduction to Strain Ageing
7. Summary of Strain Ageing
8. Return of the Yield Point
9. Strain Ageing and Atmosphere Formation
10. Strain Ageing and Dislocations
11. Strain Ageing Kinetics
12. Strain Ageing and Mechanical Properties
13. Strain Ageing and Dislocations I
14. Strain Ageing and Dislocations II
15. Dislocation Intersections and Strengthening I
16. Dislocation Intersections and Strengthening II
17. Dislocation Strengthening
18. Summary

In this module the strengthening derived from deformation and cold work will be outlined. You will also learn why steels have yield point and how this links to the phenomenon of strain-ageing.

You should also be aware that C and N dissolve interstitially in ferrite. (You should also be aware of the concept of critical resolved shear stress acting on a slip plane and the relationship between this and tension stresses.)

Learning Outcomes for this Section

After completing this section, you should be able to:

• Describe dislocation strengthening and strain ageing
• Quantify the contribution of dislocation strengthening and strain ageing to the strengthening of steels.

Pre-Requisites

Before starting, it is important that you are familiar with the following terms:  Ferrite; Dislocation; Burgers vector; Plastic deformation; Slip (of dislocations); Strain ageing (External site);

References

• Cottrell, AH,  Dislocations and Plastic Flow in Crystals, OUP,  
• Friedel, J,  Dislocations, Pergamon Press,  
• McLean, D,  Mechanical Properties of Metals, Wiley,  
• Lothe, J & Hirth JP,  Theory of Dislocations, McGraw-Hill,  
• Hall, EO,  Yield Point Phenomena in Metals an Alloys, CUP,  
• Kelly, A & Nicholson, RB,  Strengthening Mechanisms in Crystals, Elsevier Publishing,  
• Honeycombe, RWK,  Plastic Deformation of Metals, , 0-7506-4564-4 
• Reed-Hill, RE & Abbaschian, R,  Physical Metallurgy Principles, PWS,  
• Smallman, RE & Bishop, RJ,  Modern Physical Metallurgy, Elsevier Publishing,  
• Dieter, GE,  Mechanical Metallurgy, McGraw Hill, 0071004068 
• Bhadeshia, HKDH & Honeycombe, RWK,  Steels: Microstructure and Properties, Arnold,