Keith Legg 847-680-9420

Hydrogen Embrittlement Testing

HCAT Program ReviewCocoa Beach, FlDecember 2000

Keith Legg 847-680-9420

Coat, no grindCoat, no grind

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

Keith Legg 847-680-9420

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 plate1. Bright Cd plate

2. Strip center - no bake2. Strip center - no bake

3. Coat within 4 hrs, no grind3. Coat within 4 hrs, no grind

H2 fill

Does H2 escape?

Keith Legg 847-680-9420

Sequence 3 - How does environmental embrittlement compare with Cr?

CoatCoat

expose

Expose small area in notchExpose small area in notch

45% NTS Solutions - H2O and 5% NaCl Exposed notch should corrode and release H

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Exposure of bare surface for Sequence 3

Exposure of notch - 90 sector CNC machine using rounded edge blade (RBK, Seattle)

Sample

Blade

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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)

Keith Legg 847-680-9420

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

Specimen Rc hardnessH 2015 52.0, 51.9, 51.9H 2494 52.1, 51.6, 52.2H 2567 51.8, 51.7, 51.9

Keith Legg 847-680-9420

Coating deposition

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

Chrome

93.5m3.68 mils

93.5m3.68 mils

243.1m9.57 mils

HVOF31

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Embrittlement - summary

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

# samplesColumn # 1 2 3 4 5Pretest H load No No Yes YesTest environment Air Air Air AirHydrogen bake No Yes No YesGrind coating No No No NoNotch partly exposedLoad (% of NTS) 75% 75% 75% 75%Coatings:

None 9

>200>200>200

Hard chrome, 0.003” 6

0 (H1688)0

0.1

WC-Co, 0.003” 9

>200>200>200

6.14

7.8

>20077.2

129.1

WC-Co-Cr, 0.003” 9

>200>200>200

210.26.8

>200>200>200

Hard chrome, 0.010” 6

0.10.1

0 (H2511)

WC-Co, 0.010” 9

>200>200>200

10.72.84

0 (H1216)>200>200

WC-Co-Cr, 0.010” 9

>200>200>200

57.816.67.7

>200>200>200

Sequence 1 Sequence 2Baseline Hydrogen pre-test loading

Keith Legg 847-680-9420

Embrittlement - Sequence 1, not baked

Sequence 1 Unbaked Seq 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

0

100

200

Hours to failure

None Hardchrome,0.003”

WC-Co,0.003”

WC-Co-Cr,0.003”

Hardchrome,0.010”

WC-Co,0.010”

WC-Co-Cr,0.010”

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Embrittlement - Sequence 2, not baked

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

Keith Legg 847-680-9420

Embrittlement - Conclusions

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