1. IOPF 2010 Ultrasonic Characterization of Hydrogen Induced Stress in 4140 Steel IOPF2010-6001 Don E. Bray, Ph. D., P. E., Don E. Bray, Inc. PO Box 10315, College Station, Texas 77842-0315 debray1@brayengr.com http://brayengr.com debray1@brayengr.com Richard B. Griffin, Ph. D., P. E. TAMU Qatar Mechanical Engineering Program Doha, Qatar 10/21/10

2. IOPF 2010 Basis for L CR Experiments Assumption is that the block is fully charged with hydrogen in the autoclave. Chemical change to other forms of hydrogen or other chemistries is ignored. Upon removal of the block and returning to room temperature, shrinkage occurs, putting the outer surface in compression as the hydrogen escapes from the block.

3. IOPF 2010 Setup 1 2 3 Test Blocks 1 Control Block 2 & 3 Test Blocks 10/21/10

4. IOPF 2010 L CR Wave Frequency = 5 MHz Wavelength = 1.2 mm

5. IOPF 2010 10/21/10

6. IOPF 2010 Hydrogen Flow from Blocks 10/21/10

7. IOPF 2010 Equations Governing Hydrogen Movement – Fick’s Second Law 10/21/10

8. IOPF 2010 10/21/10

9. IOPF 2010 Experimental Procedures Blocks 2 and 3 sent to Honeywell for hydrogen exposure. Block 1 held in lab as control block. Data obtained on blocks 1, 2 and 3 starting 20 and 14 days after leaving autoclave. Data plotted as velocity differences (2-1 and 3-1). Experimental error ± 3 m/s. 10/21/10

10. IOPF 2010 10/21/10

11. IOPF 2010 10/21/10

12. IOPF 2010 f p = peak frequency f c = central frequency f a = low half power point f b = upper half power point Frequency Analysis

13. IOPF 2010 Results of Frequency Analysis X X – a likely anomaly 10/21/10

14. IOPF 2010 Summary of Results from Frequency Analysis 10/21/10 1.Peak (f p ) and low frequency (f a ) groups shifted downward with hydrogen exposure. 2.No significant change after removal from autoclave.

15. IOPF 2010 Summary from Photomicrographs 10/21/10 1.Decarburization at depth of 0.2 mm. 2.Decarburization layer less than 1.2 mm wavelength, 3.No effect expected on velocity due to decarburization. 4.No hydrogen induced cracking found. Specimen 3

16. IOPF 2010 Summary from Texture Analysis 3/2 8/1 0 1.XRD showed texture differences for top and bottom surfaces. 2.Texture likely reason for velocity separation for tops and bottom sides. 3.Texture may be reason for differences in post autoclave velocity pattern with time.

17. IOPF 2010 L CR2 Excitation on Opposite Wall

18. IOPF 2010 L CR2 Arrivals at 75 and 150 mm probe spacing on 15 mm plate 10/21/10 150 mm 75 mm

19. IOPF 2010 10/21/10 Conclusions L CR velocity change may be a reliable tool for research and application in measurement of reversible hydrogen buildup in metals.

20. IOPF 2010 Acknowledgements 10/21/10 The hydrogen environment was contributed by Honeywell Corrosion Solutions, Honeywell International, Inc., Houston, Texas. Dr. Malur Srinivasan of Lamar University contributed information on the texture difference between the two sides of the blocks. Mr. Jonathan Dahmann collected and analyzed much of the data.