1. Micro-scale single crystal Bauschinger effect and reversible plasticity in copper during bending MRS Fall Conference 1. Dec. 2010 Boston, USA Düsseldorf, Germany WWW.MPIE.DE d.raabe@mpie.de E. Demir*, D. Raabe * Cornell Univ. Rhodes Hall, Mechanical & Aerospace Engr. Dept.

2. Overview WWW.MPIE.DE 1

3. 2 Introduction * Bauschinger effect: flow strength change upon load path change (reversal) Demir, Raabe, Acta Materialia 58 (2010) 6055  Question: Bauschinger effect* also size dependent ?  Relevant in metal forming and cyclic straining (small parts AND small scale microstructures)  Approach: Bending and stretching experiments on a Cu single crystal

4. 3 Explanations of the Bauschinger effect Demir, Raabe, Acta Materialia 58 (2010) 6055

5. Overview WWW.MPIE.DE 4

6. 5 Experiment E. Demir, D. Raabe, Acta Materialia 58 (2010) 6055

7. 6 Set-up of experiment E. Demir, D. Raabe, Acta Materialia 58 (2010) 6055

8. Overview WWW.MPIE.DE 7

9. 8 Stress-strain results

10. 9 Microstructure and mechanical Bauschinger effect Kernal average misorientation orientation map Kernal average misorientation bending (forward) straightening (backward) Demir et al.: Acta Materialia 58 (2010) 6055 Mechanical Bauschinger effect: yield stress drop upon load path change Microstructural Bauschinger effect: microstructure reversibility upon load path change Mechanical Bauschinger effect: yield stress drop upon load path change Microstructural Bauschinger effect: microstructure reversibility upon load path change Demir et al. Acta Mater. 57 (2009) 559 ; M. Calcagnotto et al. Mater. Sc. Engin. A 527 (2010) 2738

11. 10 Microstructure and mechanical Bauschinger effect

12. Overview WWW.MPIE.DE 11

13. 12 Roters et al. Acta Mater.58 (2010) Conclusions