ARC spray on welded surface Vs parent material
10-27-2013, 03:20 PM,
#1
ARC spray on welded surface Vs parent material
Hi all,

Pretty basic question actually;

We get a lot of repair and dimensional restoration work

Now, a lot of these parts are welded to more than 10 mm on diameter.

Our usual practice is to remove the entire welding layer and put up a SS coat from the parent material with necessary bond coats etc- the usual....

My question is, can we directly coat over the welded layer after having machined and evened the surface instead of removing the entire layer? Would that compromise the quality of the coating in terms of bonding and stresses?

Most of this work has a certain guarantee period, so we need to be sure of what we are doing.....

Replies awaited .....

Regards

Shantanu
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10-27-2013, 08:40 PM,
#2
RE: ARC spray on welded surface Vs parent material
Hi shantanu
If the maining is about welding coatings, as I understand, you must know why do they welded it before, and as well as you know thermal coatings do not add structural resistence to the piece, and you must know the function of the coating you want to apply, there is not problems to apply a thermal coating on welded surface, except when it is not possible to sand-blast the surface because the welding coating is very hard.
Best regards
Luigi
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10-28-2013, 12:38 AM,
#3
RE: ARC spray on welded surface Vs parent material
(10-27-2013, 08:40 PM)loriolo Wrote: Hi shantanu
If the maining is about welding coatings, as I understand, you must know why do they welded it before, and as well as you know thermal coatings do not add structural resistence to the piece, and you must know the function of the coating you want to apply, there is not problems to apply a thermal coating on welded surface, except when it is not possible to sand-blast the surface because the welding coating is very hard.

Hi loriolo,

In many cases, cos have chosen welding because if un availability of thermal spray coaters!

Cases I was referring to we're all machinable WELDINGS, so making a profile would not be an issue- just worried on own the bonding compares of a thermal sprayed coating compares to when put on a welded layer Vs a solid parent layer....what of the welded layer had inherent cracks, blow holes etc- possibility of which is always high....

Thanks for your reply

Shantanu
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10-28-2013, 08:36 AM,
#4
RE: ARC spray on welded surface Vs parent material
Dear Mr.Shantanu,
Its always advisable to check the condition of the welded layer.
Vijay
Reply
10-29-2013, 05:32 AM,
#5
RE: ARC spray on welded surface Vs parent material
Hi Shantanu,

Since your question focuses on the bonding of the Arc Coating to the Substrate, and since the weldment seems to be machinable (so you can machine it and get the blast profile), then I think you are safe to guarantee the coating. Actually I expect your Thermal Arc Spray coating at 10mm (unless its babbit) is a bit more worrisome than a 1 mm coating on a previously welded surface.

Also I might also note that since the welded surface has been used, then probably the welding interface to the substrate is also acceptable, by default, since it has been used in service. However maybe a crack check, and UT check would be a good idea.

And as I always stress with our customers, if the part has been welded by 10 mm Radius in the past, something unusual was happening in the system (bearing / rotating elements failure) and that failure mechanism is not covered in the warrantee.

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

Reply
11-04-2013, 08:03 PM,
#6
RE: ARC spray on welded surface Vs parent material
(10-29-2013, 05:32 AM)Stephen Booth Wrote: Hi Shantanu,

Since your question focuses on the bonding of the Arc Coating to the Substrate, and since the weldment seems to be machinable (so you can machine it and get the blast profile), then I think you are safe to guarantee the coating. Actually I expect your Thermal Arc Spray coating at 10mm (unless its babbit) is a bit more worrisome than a 1 mm coating on a previously welded surface.

Also I might also note that since the welded surface has been used, then probably the welding interface to the substrate is also acceptable, by default, since it has been used in service. However maybe a crack check, and UT check would be a good idea.

And as I always stress with our customers, if the part has been welded by 10 mm Radius in the past, something unusual was happening in the system (bearing / rotating elements failure) and that failure mechanism is not covered in the warrantee.

Thanks Stephen. Your reply was helpful as always
Reply




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