Modelling and Simulation of grain size evolution

1. Modelling and Simulation ofgrain size evolution Institut of Metal Forming Dr. rer. nat. Martin Franzke Innovationsforum Florianópolis 2008

2. Contents • Introduction • Basics of MSI (MicroStructureSimulation) • Industrial application (forging of a turbine disk)

3. Microstructure evolution during forming Hardening Coarse initial Dynamic grain Recovery recrystallised Dynamic final grain Recrystallisation Roll gap Static Recrystallisation Static Recovery Forming texture

4. 100µm sF 100µm smax sstat 100µm ecrit emax estat Flow stress and metallography

5. IN 706 at 950°C and j = 10 s-1 dDRX = 12.9 µm 1 3 2 dDRX = 6.6 µm dDRX = 18.7 µm Dynamic recristallisedaverage grain size in mm StrucSim - Microstructure simulation during compression of Inconel706 LARSTRAN/Shape

6. Forging of a turbine disk - Process design • Heating the cylindrical billet from 20oC up to 1040oC • Transport from the furnace to the press • Shaping the billet in an one step closed die forging process

7. Forging of a turbine disk - Boundary conditions • Die velocity 20mm/s • Die temperature 650oC • Friction (Coulomb ) 0.25 • Heat transfer () 0.002 W(K*mm2) • Emission () 0.9 • Surrounding temperature 30oC • Time for closed die operation 8.7s

8. Forging of a turbine disk - Heating 196 mm Heating time of 2000s is sufficient to reach the core temperature of 1040oC 100 mm

9. Forging of a turbine disk - Transport (radiation)

10. Forging of a turbine disk - Closed Die Operation

11. Forging of a turbine disk - Closed Die Operation

12. Forging of a turbine disk - Closed Die Operation Folding!

13. Forging of a turbine disk - Closed Die Operation

14. Forging of a turbine disk - Closed Die Operation

15. Forging of a turbine disk - Closed Die Operation

16. Validation

17. Summary • Boundary conditions are still the weak point • Simulation of grain size evolution is already available for a number of materials • Computing time is not really the limiting factor