Transcript Status of HCAT Fatigue Testing 1996 to Present

Status of HCAT Integrity/Fatigue
Testing
John P. Sauer
Sauer Engineering
February 20th, 2002
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
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
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
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
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
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
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
Axial Fatigue Big Bars-Future
• NAVAIR Big Bars (Eui will cover)
• HCAT Alternate coatings-.010” thicknessHitemco ( depends on small bar results)
– WCCo self fluxing
– NiAl
– T-400
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
Bend Testing Future
QC TYPE TESTING
• Goodrich
• Hollow bend specimen –3 pt bending
• Hill
• Hollow bend specimen –4 pt bending
varied wall thickness
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??
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
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
Protocol/Part
Source
Coating
Gun
Comments
Jerry Schell
Optimized
Northwestern
Hill
WCCo
JP 5000
Landing Gear HCAT
(fatigue/Corrosion)
Hitemco
WCCo
DJ 2600
Jerry Schell
Optimized
Landing Gear HCAT
(wear/hydrogen
emb/SCC/drop tests)
SW
WCCo
DJ 2600
Boeing Parameters
Famous 40
SW
WCCo
DJ 2600
Jerry Schell
Optimized
NAVAIR Big Bars
Hitemco
WCCo
DJ 2600
Jerry Schell
Optimized
Prop Hub
Engelhard
WCCo
DJ 2600
Boeing Parameters
High Almen
(development)
CCAD Cherry Point
WCCo
DJ 2600
Work to suppot
langing gear protocol
A-10 pistons and
limited test bars
Hill
WCCo
JP 5000
Jerry Schell
Optimized
A-10 pistons and
limited test bars
Engelhard
WCCo
DJ 2600
Boeing Parameters
High Almen
AFRL Test bars
CTS
WCCo
JP 5000
Jerry Schell
Optimized
Landing Gear
CHCAT (fatigue,
wear, corrosion)
Vac Aero
WCCoCr
DJ 2600
NRC Jean
parameters
Limited test bars
Hill
WCCoCr
DJ 2600
Jerry's guess
Famous 40
SW
WCCoCr
DJ 2600
SW parameters
Goodrich Bend
Sample
Vac Aero
WCCoCr
DJ 2600
Sulzer prameters
Messier Dowty Parts
Engelhard
Vac Aero
SW
Praxair
WCCoCr
DJ 2600
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!!!
Process Control and Maturity
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
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
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!!
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
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