Help regarding dimensional restoration on Fe430 - S275
10-09-2016, 10:23 AM, (This post was last modified: 10-10-2016, 04:26 PM by MVagusta.)
#1
Help regarding dimensional restoration on Fe430 - S275
Hello everyone,

i've a customer who asked me to apply coating on a 360 mm diameter tube made of Fe430 (s275) for dimensional restoration, weight of the component is about 250-300 kg.

I've tried several times to apply coating by oxy-acetylene flame with my Uni Spray Jet from UTP (similar to castodyn DS 8000) but coating fails to adhere to the substrate and it comes off when cutting it on the lathe. Coating is about 0.5-0.6mm once turned on the lathe (0.8-0.9 mm as sprayed).

Procedure that i followed is:
- Acetone cleaning
- Surface preparation by turning it on the lathe removing few cents of material JUST BEFORE COATING.
- NO grit blasting as job is being done on customer site and i don't have a vacuum blasting equipment to salvage the material being used and not mess everything around. Piece won't fit my gritblasting cabinet as well.
-NO preheating as the surface being coated, if directly heated with the flame, tends to become yellowish (oxidize) pretty quickly but the piece, due to it's big mass, doesn't warm up at all (after 10 minutes of coating it's around 100°C)
- Coating with NiAl 95/5 (45-90um) with neutral flame.

I'm going to give it a last try grit blasting the surface prior to coating as it should be done but i knew, not from experience, that NiAl should be able to bond also to "shiny metal". Isn't that true?

Do you have any suggestione/advice to give me?
Grit blasting should be the final solution but i'd like to have your opinion as well perhaps i'm missing something......

Thanks a lot and sorry for the long post!
have a nice day!
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10-11-2016, 07:24 AM,
#2
RE: Help regarding dimensional restoration on Fe430 - S275
Dear MVagusta

Just a couple thoughts for your consideration:

1. SS has higher thermal expansion compared to Steels, even from 20C to 100C
2. Grit blasting is a must

Suggestions,
a) make temporary blast cabinet, and preheat part on the lathe, to about 120C, soaking heat
b) blast after the pre-heat
c) maintain the heat during the coating
d) slow cool the part after coating
e) make sure you mask carefully in advance














Stephen James Booth
www.ipsteknokraft.com
www.teknokraft.com
Indonesia WhatsApp +6281905603262

Reply
10-11-2016, 08:54 AM, (This post was last modified: 10-11-2016, 08:59 AM by MVagusta.)
#3
RE: Help regarding dimensional restoration on Fe430 - S275
(10-11-2016, 07:24 AM)Stephen Booth Wrote: Dear MVagusta

Just a couple thoughts for your consideration:

1. SS has higher thermal expansion compared to Steels, even from 20C to 100C
2. Grit blasting is a must

Suggestions,
a) make temporary blast cabinet, and preheat part on the lathe, to about 120C, soaking heat
b) blast after the pre-heat
c) maintain the heat during the coating
d) slow cool the part after coating
e) make sure you mask carefully in advance
Hi Stephen,
thank you very much for your help.

just for my understanding, when you say SS i think you mean Stainless Steel. The pieces i need to coat are made of structural low carbon steel (S275 european designation, i think the US equivalent should be A570Gr40).
It's not Stainless steel or an high alloyed steel.

I got that gritblating is a must and i'll do that.
Do you think that preheating is also a must? or can i skip it? As i said it takes 10+ minutes of coating for the component to reach 100°C from room temperature. As i have to coat 20 of them it will be a very long process. Of course it's better having a long process than a faster one but then seeing the coating spalling of when turning it :-)

Thanks again for your help!


Reply
10-15-2016, 10:18 AM,
#4
RE: Help regarding dimensional restoration on Fe430 - S275
Hi MV Agusta

Correct,I was thinking it was Stainless.

Grit blasting is a must, and probably integral to the solution.

Preheat, maybe not absolutely a must, but if you could do the preheat, would be excellent.
Stephen James Booth
www.ipsteknokraft.com
www.teknokraft.com
Indonesia WhatsApp +6281905603262

Reply
10-15-2016, 10:01 PM, (This post was last modified: 10-15-2016, 10:20 PM by Met.Eng..)
#5
RE: Help regarding dimensional restoration on Fe430 - S275
Smile the point is bonding, try this step by step

1 - You must preheat the shaft about 150-200 C
2- Than turning the substrate the surface
3- check the surface temp , if it is cool down than preheat again and dont spray bond coat under 100 - 150 C its important!!!!!
4- than 0.7 mm depth x 0.7 mm pitch surface preparation , if your lathe cant pitch this you can do 1 mm x 1 mm pitch ( if you preheat after the surface preparation may be come oxidation the surface )
5- apply bont coat 100-150 mic max thickness
6- than apply the top coat

Check the metco NiAl bulletin, couse the niAl powder is exoteric reaction during the spraying, you have to spray one pass 100 -150 mic bont coat)
My opinion is try to use metco 480 for bont coat
The max surface tem during the spraying is 200 C

Good luck
Reply
10-18-2016, 08:20 AM, (This post was last modified: 10-18-2016, 08:52 AM by MVagusta.)
#6
RE: Help regarding dimensional restoration on Fe430 - S275
(10-15-2016, 10:18 AM)Stephen Booth Wrote: Hi MV Agusta

Correct,I was thinking it was Stainless.

Grit blasting is a must, and probably integral to the solution.

Preheat, maybe not absolutely a must, but if you could do the preheat, would be excellent.

Thanks!
I still have to do the job and i'll definitely grit blast the substrate but what about the claim that NiAl is a selfbonding material and thus should be able to bond even to smooth metal? Any experience with that?

Thanks a lot again!
(10-15-2016, 10:01 PM)Met.Eng. Wrote: Smile the point is bonding, try this step by step

1 - You must preheat the shaft about 150-200 C
2- Than turning the substrate the surface
3- check the surface temp , if it is cool down than preheat again and dont spray bond coat under 100 - 150 C its important!!!!!
4- than 0.7 mm depth x 0.7 mm pitch surface preparation , if your lathe cant pitch this you can do 1 mm x 1 mm pitch ( if you preheat after the surface preparation may be come oxidation the surface )
5- apply bont coat 100-150 mic max thickness
6- than apply the top coat

Check the metco NiAl bulletin, couse the niAl powder is exoteric reaction during the spraying, you have to spray one pass 100 -150 mic bont coat)
My opinion is try to use metco 480 for bont coat
The max surface tem during the spraying is 200 C

Good luck

Hi Met.Eng.,
thanks for your help!

I appreciate that your procedure is applicable when you can't gritblast the piece being coated. I can give this procedure a try even though i'm now going to grit blast the pieces.
By the way a 0.7 mm dept thread seem to me a little too deep... in the end we have to fill it with material afterwards :-), are you sure about it?

I'm not going to apply any top coat but finish it with NiAl as i have it readily available. It should be ok for the purpose.

Thanks again


Reply
10-19-2016, 06:38 PM,
#7
RE: Help regarding dimensional restoration on Fe430 - S275
(10-18-2016, 08:20 AM)MVagusta Wrote:
(10-15-2016, 10:18 AM)Stephen Booth Wrote: Hi MV Agusta

Correct,I was thinking it was Stainless.

Grit blasting is a must, and probably integral to the solution.

Preheat, maybe not absolutely a must, but if you could do the preheat, would be excellent.

Thanks!
I still have to do the job and i'll definitely grit blast the substrate but what about the claim that NiAl is a selfbonding material and thus should be able to bond even to smooth metal? Any experience with that?

Thanks a lot again!
(10-15-2016, 10:01 PM)Met.Eng. Wrote: Smile the point is bonding, try this step by step

1 - You must preheat the shaft about 150-200 C
2- Than turning the substrate the surface
3- check the surface temp , if it is cool down than preheat again and dont spray bond coat under 100 - 150 C its important!!!!!
4- than 0.7 mm depth x 0.7 mm pitch surface preparation , if your lathe cant pitch this you can do 1 mm x 1 mm pitch ( if you preheat after the surface preparation may be come oxidation the surface )
5- apply bont coat 100-150 mic max thickness
6- than apply the top coat

Check the metco NiAl bulletin, couse the niAl powder is exoteric reaction during the spraying, you have to spray one pass 100 -150 mic bont coat)
My opinion is try to use metco 480 for bont coat
The max surface tem during the spraying is 200 C

Good luck

Hi Met.Eng.,
thanks for your help!

I appreciate that your procedure is applicable when you can't gritblast the piece being coated. I can give this procedure a try even though i'm now going to grit blast the pieces.
By the way a 0.7 mm dept thread seem to me a little too deep... in the end we have to fill it with material afterwards :-), are you sure about it?

I'm not going to apply any top coat but finish it with NiAl as i have it readily available. It should be ok for the purpose.

Thanks again

0.7 mm for diamentional , 0.7 / 2 = 0.35 mm for one side depth
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