Crack indication Stellite 1 HVOF

[achmadarifudinh]

Hello guys

Help me please
i have case that my stellite 1 HVOF spray already done with thickness 180 - 270 microns. But my customer want to do red dye penetrant testing in coating spray. This is the 1st time i do red dye penetrant testing in coating spray.
i attach photo, my penetrant testing in to coated part result

   

i wanna ask, is this method (red dye penetrant testing) is suitable to spray coating ??
and
how to do correct method spray to prevent this coating cracks.

FYI
powder Stellite 1 Durametal HVOF
HVOF DJ 2600 (hydrogen)
Hybrid gun

Thank you so much
regards

[velocity]

Hello guys

Help me please
i have case that my stellite 1 HVOF spray already done with thickness 180 - 270 microns. But my customer want to do red dye penetrant testing in coating spray. This is the 1st time i do red dye penetrant testing in coating spray.
i attach photo, my penetrant testing in to coated part result



i wanna ask, is this method (red dye penetrant testing) is suitable to spray coating ??
and
how to do correct method spray to prevent this coating cracks.

FYI
powder Stellite 1 Durametal HVOF
HVOF DJ 2600 (hydrogen)
Hybrid gun

Thank you so much
regards

Suitable or not cracks are real and penetration test doesn' t cause that.
My question is about geometry. Is it a kind of blade or is the other side of coating has also coating?
Edges are heating faster then thick area and cooling rate may cause this. Are you preheating tool? Cooling with air or slowly?

[Met.Eng.]

Hi Achmadarifudinh

I thing ur problem is cooling. You can try this method

Preheat 100-120 C
Apply 50 micron bond coat (arcspray is best way i thing )
And than spray top coat. Preheating is important!!! Ur first top coat lyres have to confort heated surface.

Good luck

[achmadarifudinh]

Hello guys

Help me please
i have case that my stellite 1 HVOF spray already done with thickness 180

Suitable or not cracks are real and penetration test doesn' t cause that.
My question is about geometry. Is it a kind of blade or is the other side of coating has also coating?
Edges are heating faster then thick area and cooling rate may cause this. Are you preheating tool? Cooling with air or slowly?

Thank you for ur reply sir.
It's kind of blade in leading area section. i coated 25 cm from tip blade with 2cm width. that's true leading edge have curve geometry.
am already do preheating to 100-120 celcius as ASM 5A reference.
is it meaning for cooling air is cooling air in side coated blade when blade is spraying ??
or cooling air when blade after coated ??

Thanks
Regards
Achmad

[Stephen Booth]

my thoughts:
try to maintain the preheat, and keep the heat during the spraying, and allow for slow cooling, I would suiggest even a bit higher on the temperature even to 200C but not going over 250C, and slow cool in Vermeculite

[Stephen Booth]

as of 2021 are there any formal OEM or Certification standards (ISO or API or similar) for the inspection of HVOF WC coatings using dye penetrant.

customers often asking for this type of NDT, but my stance is Dye Penetrant on HVOF coatings is not a valid test:

any one have any formal documentation on this?