Status of HCAT Integrity/Fatigue Testing

1. Status of HCAT Integrity/Fatigue Testing John P. Sauer Sauer Engineering February 20th, 2002

2. Presentation Outline • History • Current and future work • Small/Big Bar Axial Fatigue/Coating Integrity • Bend Testing • Goodrich • Hill • Process Control and Maturity • Update-Almen • Summary

3. History • Spalling issue is the current show stopper • Identified as an issue as we have moved form Boeing low load R = .1 testing to military directed higher load R = -1

4. Methods-Coating Integrity • Four ways to address issue • Testing (Is it representative??) • Type/size of specimen • Method of testing axial vs. bend • Process/Material • New coating chemistry/combinations • Understanding how process can vary and the effect on spalling tendency

5. Axial Fatigue-Current • Small axial bars have comprised the majority of the testing • General 1st thought in all protocols as all baseline substrate data based on this slight variations of this geometry • Current threshold • 180-200 ksi at R = -1 for .003 “thickness • 160-180 ksi at R = -1 for .010 “thickness • Some limited work at Hill raises these numbers

6. Axial Fatigue • Integrity testing regime is currently: • 190 to 240 ksi • R ratio of -.5 to -1.0 • Run ???? cycle increments stepping 10 ksi after each cycle set-look for cracking, etc. • Stop at load when coating has spalled-save bar for analysis OR • When reach 240, cycle to failure

7. Axial Fatigue-Future • More work on bars at Hill process that show higher threshold • Work on three new coatings at .010” thickness • Self fluxing WCCo • NiAl as a bond coat • T-400 as a bondcoat

8. Axial Fatigue Big Bars Current • Response to fact that small bars don’t represent real parts • NAVAIR Big Bars • 180 ksi R = - 1 threshold at .003” thickness • 160 ksi R = - 1 threshold at .010” thickness • HCAT Big Bars • Phil to cover

9. Axial Fatigue Big Bars-Future • NAVAIR Big Bars (Eui will cover) • HCAT Alternate coatings-.010” thickness-Hitemco ( depends on small bar results) • WCCo self fluxing • NiAl • T-400

10. Bend Testing Current COMPONENT ( more like real parts) • Goodrich • Testing in progress Ben/Roque to discuss • More testing on pistons planned in future • Hill • Bend testing on A-10 pistons shows good promise at up to 240 ksi R =-1 • More testing in progress

11. Bend Testing Future • QC TYPE TESTING • Goodrich • Hollow bend specimen –3 pt bending • Hill • Hollow bend specimen –4 pt bending varied wall thickness

12. Current Issues-Higher stress-R ratios • What are the exact cracking thresholds?? • What exact factors affect the tendency to crack/delaminate/spall?? • Testing or process parameters/variation??

13. Process Control and Maturity CURRENT STATUS • Reliable process understanding below 180 ksi and R = .1 with no spalling issues • Coating suppliers with Boeing (170 ksi R = .1) approval can supply coatings for commercial applications • Meet the QC tests and use approved processes which are not system driven • Many suppliers with varied processes approved

14. Process Control and Maturity NEW ISSUE • With the identification of the spalling issue at higher loads, this same process reliability is not a given • Current QC tests do not seem to give any indication about spalling behaviour • Many processes within HCAT/CHCAT on variety of test programs

17. Process Control and Maturity • How do we determine the reliability of the HVOF spray process with regard to spalling with so many parameter sets in the mix?? • How do we rank one set of parameters vs. another or understand how a spray variable affects spalling? • At this point, we don’t have the answers!!!

18. Process Control and Maturity

19. Process Control and Maturity • With this in mind, it is suggested we need to better understand the process and identify a screening test with regard to spalling • Can it be a new QC test?? Bending?? • Volvo uses a bend test/count the cracks • Praxair uses acoustic emission

20. Process Control and Maturity • A plan is now being considered that dovetails both the need to understand the process and evaluate the best test methods to make this happen (Jean Gab/John/Keith) • It will evaluate the many parameter sets used within HCAT and work to develop the needed screening test to determine spalling tendencies • The ultimate outcome would be a QC screening test

21. Process Control and Maturity • This will address our ultimate goal for process control in production: • If a set up meets initial fatigue qualification and QC tests, it doesn’t matter what parameters are used • This will mean varied guns, fuel gases, and parameter sets will be approved • This work needs to be done!!

22. Almen/Temp • Previous presentation presented summary on HCAT endorsed method of crosswise/grit blast both sides • Temp measure tech is critical especially for spot size in measuring fatigue bars • Recent work indicates depo rate is another key issue • New document available on website as part of LG JTP report

23. Summary • Issues still exist at R =-1 and higher stress levels • Must work on: • Test methods • New materials • Process understanding • This will allow us to solve the spalling issue