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Hydrogen Embrittlement Testing

Hydrogen Embrittlement Testing. HCAT Program Review Cocoa Beach, Fl December 2000. Sequence 1 - Make sure that HVOF does not cause embrittlement. ASTM F-519, Type 1a.2 75% NTS All experience shows HVOF does not cause embrittlement Just makes sure. Coat, no grind.

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Hydrogen Embrittlement Testing

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  1. Hydrogen Embrittlement Testing HCAT Program Review Cocoa Beach, Fl December 2000

  2. Sequence 1 - Make sure that HVOFdoes not cause embrittlement • ASTM F-519, Type 1a.2 • 75% NTS • All experience shows HVOF does not cause embrittlement • Just makes sure Coat, no grind

  3. Sequence 2 - can H from other plating or stripping escape through HVOF? • 75% NTS • Using bright Cd so as to avoid excessive diameter and inability to hold in grips • No way for H to escape at center except through HVOF 1. Bright Cd plate 2. Strip center - no bake H2 fill 3. Coat within 4 hrs, no grind Does H2 escape?

  4. Sequence 3 - How does environmental embrittlement compare with Cr? • 45% NTS • Solutions - H2O and 5% NaCl • Exposed notch should corrode and release H Coat Expose small area in notch expose

  5. Exposure of bare surface for Sequence 3 • Exposure of notch - 90 sector • CNC machine using rounded edge blade (RBK, Seattle) Blade Sample

  6. Hydrogen embrittlement • Samples produced by Southwest Aeroservice (Jim Nuse, Dave Sommerville) • Sequences 1 and 2 work by Metcut (Phil Bretz) • Sequence 3 by Boeing (Dennis Dull)

  7. Base material • Expected NTS 260 ksi • Tested at 362,416 to 382,521, average = 373,600 ksi • Sequence 1 and 2 testing at 280.2 ksi • Rockwell hardness

  8. Chrome penetrates into notch thinner at notch bottom HVOF deposits best by angling gun and blowing excess powder away with strong jet thicker at bottom 93.5m 3.68 mils 93.5m 3.68 mils 243.1m 9.57 mils Coating deposition Chrome HVOF 31

  9. Table shows hours to failure (pass>200) Sequence 1 Col 3 currently under test originals not baked Sequence 2 Uncoated samples currently under test - no baseline yet originals not H-loaded Sequence 3 testing begun - uncoated baseline in test Blue samples at Boeing for metallography Embrittlement - summary

  10. Sequence 1 UnbakedSeq 1 show HVOF does not cause embrittlement Baked baseline (0.003” and 0.010” Cr only) currently under test Two Cr samples at Boeing for metallography to check failure mode Embrittlement - Sequence 1, not baked

  11. No immediate failures Need to acquire uncoated baseline Baking removes most H2 Not completely removed in WC-Co One immediate failure WC-CoCr 0.010” Being analyzed at Boeing Embrittlement - Sequence 2, not baked

  12. Sequence 1 HVOF does not cause embrittlement Baked chrome baseline being acquired Sequence 3 In progress Sequence 2 Failure not immediate without bake Need baseline comparison Some H2 removal by flame? Reduced Kt? Bake removes H2 from most samples Except WC-Co 0.003 - why? Immediate fail WC-Co 0.010” being examined at Boeing Baseline uncoated (i.e. coated and stripped) being acquired Embrittlement - Conclusions

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