Diamalloy 1008 H.D. Crankshaft Repair

[HVoilF]

Does anybody have any experience in the use of Diamalloy 1008 JP5000 sprayed for the H.D. Diesel Crankshaft repair? We have seen a lot of crankpin failure in Gas turbocharged big crankshaft used in the oil/gas industry repaired with arc spray coatings either using 420 SS or tough hard cored wire as Tafa 95MXC (bot suggested as good materials for crankshafts rebuilding......) In our experience only some High Carbon Plasma sprayed powders work fine for HD crankshaft repair. Arc spray could probably only be used for light gas and air compressor crankshafts. Any opinion on this subject?
Does anybody have the JP5000 spraying parameters for the Diamalloy 1008 powder?

[Gordon]

Hi HVoilF

I've only come across Diamalloy 1008 (FeCrMo alloy blend) when it was first introduced and did some spray trials and coating evaluation through the first air cooled DJ gun. Looked like an interesting coating and appeared to do what was said on the tin. Not come across it since though, so can't comment on actual service performance, but it sounds an interesting choice for crankshaft repair.

Have my doubts whether you will get hold of good optimised parameters for 1008 for the JP5000 (any you can trust anyway ), so you will probably need to do some spray trials and optimise it yourself. I would be inclined to keep coating thickness below ~0.020" (0.5 mm) and use a NiAl bond coat if you need to go thicker.

What surface treatments have the HP crankshafts had originally - nitrided, induction hardened, fillet hardened or not etc.? As you know not all crankshafts are the same Are you repairing mains or pins (including fillets or side walls or not)?

[HVoilF]

Yes some cranks were nitrided,we normally don't spray over the fillets or side walls,just the cilindrical area of the journal. As you suggest we are making some sprayed samples in order to get the best spraying parameters. Do you have any experience on some Plasma or HVOF material for crankshaft repair?

Gordon Wrote:Hi HVoilF

I've only come across Diamalloy 1008 (FeCrMo alloy blend) when it was first introduced and did some spray trials and coating evaluation through the first air cooled DJ gun. Looked like an interesting coating and appeared to do what was said on the tin. Not come across it since though, so can't comment on actual service performance, but it sounds an interesting choice for crankshaft repair.

Have my doubts whether you will get hold of good optimised parameters for 1008 for the JP5000 (any you can trust anyway ), so you will probably need to do some spray trials and optimise it yourself. I would be inclined to keep coating thickness below ~0.020" (0.5 mm) and use a NiAl bond coat if you need to go thicker.

What surface treatments have the HP crankshafts had originally - nitrided, induction hardened, fillet hardened or not etc.? As you know not all crankshafts are the same Are you repairing mains or pins (including fillets or side walls or not)?

[Stephen Booth]

Hi again, one of the key factors in the coating of the crankshaft is the rotation (RPM) of the part and traverse speed of the torch during the coating, with the goal to achieve as thin as possible layers of the coating. the goal of which is to reduce the internal stresses in the coating, which lead to cracking. Other contributing factors might be:

1. overall thickness of the coating
2. surface treatment of OEM part
3. parameters
4. preheat and interpass temperatures, you might try using some cooling device during the spraying operation.
5. Surface preparation to achieve best roughness

[hvofhamid]

Stephen Booth Wrote:Hi again, one of the key factors in the coating of the crankshaft is the rotation (RPM) of the part and traverse speed of the torch during the coating, with the goal to achieve as thin as possible layers of the coating. the goal of which is to reduce the internal stresses in the coating, which lead to cracking. Other contributing factors might be:

1. overall thickness of the coating
2. surface treatment of OEM part
3. parameters
4. preheat and interpass temperatures, you might try using some cooling device during the spraying operation.
5. Surface preparation to achieve best roughness

hello
-overall thinckness of coating is not the raison of cracking,but the thermic effect is the raison :
-if you respect the substrat heat you stop dilatation,then you can coat the thickness you like
-preheat is not necesser if parameters of rotation and speed torch are adequat,the first pass can preheat
-surface preparation is important and air colding device can help to avoid cracks