1. 07/20/07 Evaluation of Load Damage in Steel Using The L CR Ultrasonic Technique Don E. Bray, Ph. D., P. E. Don E. Bray, Inc. P. O. Box 10315 College Station, Texas USA 77842-0315 Voice/Cellular 979-492-9534 Email debray1@brayengr.com http://brayengr.com PVP2007/CREEP8 Conference July 22-26, 2007, San Antonio, Texas USA

2. 07/20/07 Schematic of L CR Probe

3. 07/20/07 Beam Profile for L CR Wave

4. 07/20/07 Interrogation Area for L CR (from Bray and Tang, 2001) w - distance between two half power points on energy distribution curve d - distance between outer surface and the peak energy point

5. 07/20/07 Tensile Specimen Used for Ultrasonic Studies

6. 07/20/07 Relationships of the L CR travel time (t) versus stress (From Tang and Bray, 1996).

7. 07/20/07 Relationship of the L CR travel time (t) versus residual strain. (From Tang and Bray, 1996).

8. 07/20/07 f p = peak frequency f c = central frequency f a = low half power point f b = upper half power point

9. 07/20/07 Frequency Analysis Definitions f c = 0.5 (f b + f a ) f sk = (f p - f a )/(f b - f p ) Bandwidth = B = f b - f a ICPIIT Houston, Texas USA 18-22 June 2001 Don E. Bray, Inc., College Station, Texas 77842-0315

10. 07/20/07 Fb and KIC (McGrath and Bray 2001)

11. 07/20/07 Setup for Present Experiments

12. 07/20/07 Table 1 Velocities (m/s) for locations on the steel bar

13. 07/20/07 Table 2a z-Test Comparing End and Center Data Two Sample Means for F a

14. 07/20/07 Table 2b z-Test Comparing End and Center Data Two Sample Means for F c

15. 07/20/07 Hydrogen Attack Imanaka and Suetsugu (1995) - showed just less than 10% increase in travel time for samples exposed to hydrogen. Kot (2001) - compares NDE methods for evaluating H 2 attack. Dismisses creeping wave technique because it does not provide information about the opposite surface.

16. 07/20/07 Propagation on Inner Surface

17. 07/20/07 Arrival Time Equations

18. 07/20/07 Typical L CR Arrivals 150 75 R2-R1 mm

19. 07/20/07 Latest L CR Probe

20. 07/20/07 Using the Probe

21. 07/20/07 Conclusions Velocity data and frequency analysis can be used to evaluate load damage in steel parts. Suggests that L CR could be used to interrogate the inside wall of structures for hydrogen damage.