1. The Effect of Thermal-mechanical Treatment on Abnormal Grain Growth on Friction Stir Welded Al-Li Richard Wellnitz & Anthony D. Barajas Dr Howard – project superviser

2. What is Abnormal Grain Growth?
SAMPLE H
STD
Massive Grains
(.5-1 mm)
Small Rounded Grains (3-5 microns)

3. Objective To Find Out Does Hot rolling have an affect on grain growth?
Does cold rolling have an affect on grain growth?
Does step heating have an affect on grain growth?

4. Possible Applications

5. Other possible applications
Other possible applications in pictures examples of cars trains planes etc.

6. Presentation Organization
Introduction
Theory
Methods and Equipment
Charts
Description of Results
Summary and Conclusions

7. Theory
Introducing a process of cold working or cold rolling may inhibit this formation of abnormal grain growth by breaking the structures along the slip plane.
Face Centered Cubic on plane
Shifting along the Slip plane

8. The FSW equipment FSW AT 200 RPM 4 IPM TOOL ANGLE 3.5 DEG
POSITION CONTROL WITH “HEEL PLUNGE

10. Thermal Response of Hot Roll Furnace

11. Actual Thermal History of a Monitored Sample During Grain Initiation

13. Sample layout Bead on Plate down center of plate Hot work Step Heating
Cold Work
Samples

14. Step Heating
Step heating-Initially brought up to 750 F And continually increased by 50 degrees each hour afterwards to 950 F
50 F
950 F
1 HOUR
50 F
Temp
1 HOUR
50 F
1 HOUR
50 F
1 HOUR
750 F
Oven and samples heated to 750 degrees prior to step heating
Time

15. Standard Samples STD-FSW Only H-Heated with hot roll samples
ASAW – FSW and Solution Heat treatment
ASFSW- FSW Only

16. Rolling

17. Processing schedules Hot work- 10%,20%,30%,40%
Cold work- 5%,20%,25%,30%
% OF REDUCTION
THICKNESS OF SAMPLE
T 1
T 2

18. Polishing Samples surfaces were polished with silicon carbide 240 grit
alumina suspension polish to .1 micron

19. Etching Etching- bringing out the grain Samples were etched with
10% Sodium Hydroxide solution – 60 seconds
Rinsed –distilled water
Washed in– 50% Nitric Acid Solution

20. Results of Hot Roll
Reduction
10%
20%
30%
40%
.320
Original
Thickness

21. Results of Cold Roll
Reduction 5%
20%
25%
30%
.320
Original
Thickness

22. Conclusions Substantial Grain growth occurs in Al-Li 2195
Hot working doesn’t eliminate or reduce grain growth
Hot work might actually increase grain growth
There is substantial grain growth reduction above 20% cold rolling
Step heating does not decrease grain growth

23. Suggested additional work
Image analysis for grain size (statistical)
Additional cold work between 5% and 20%
Further metallurgical testing for hardness toughness
Tensile strength ductility
Fatigue life
Microscopy

24. Acknowledgements Bill Arbegast-AMP Dr. Stone-MET Santosh Koduri
K.B. Anand
Srikanth Labhala
Eric Henderson
Tyler Engstrom
Colleen Gustafson
Casey Allen
Brian Tweedy

25. Discussion Why is cold work effective
At what point is cold work effective
Does hot rolling increase the grain growth