Welding Flaw?

[LakeShark]

What would cause this white ring around the welds on a motor mount? It's all stainless and arrived for the mfr. this way but only on one of the tubes of an outboard bracket. all of the other tubes are perfectly clean around the welds. Will this become an issue over time?

 

[dLj]

That's an unusual pattern. It looks to me more like they may have used a chemical product to clean the weld discoloration and then didn't either clean correctly or finish polishing correctly.

I would need much more detailed images to give you more input.

dj

 

[LakeShark]

That's an unusual pattern. It looks to me more like they may have used a chemical product to clean the weld discoloration and then didn't either clean correctly or finish polishing correctly.

I would need much more detailed images to give you more input.

dj

the company I bought it from is reaching out to the manufacturer as well. There is discoloration on one of the 4 tubes only but it’s at every single weld bead with that tube. The discolored part is rough to the touch and does not scrape off with a fingernail.
Thanks for the input but any additional information you could shed on this would be greatly appreciated. Will this be a point of corrosion, weakness, etc.?

 

[dLj]

Rough to the touch sounds like improper use of cleaning or lack of polishing.

Yes, rough to the touch will mean greater propensity to future corrosion. More info would require a lot more data.

dj

 

[dLj]

In more detail - the question you are asking will often fall into the engineering realm of "fitness for service" a very indepth process of evaluating if something in less than ideal conditions is still able to perform its function. In order to really give an in depth answer, I would need to know the wall thickness of the tubing, the wall thickness of the region you have identified, the loadings that part will be subjected to. Those data would be required to do a structural assessment.

From a corrosion point of view, as it is a rough surface, it will have greater tendency for corrosion.

To know if it can be polished to remove the discoloration, one would need to know exactly how much material is present. If they simply missed polishing this section, just repolish and you are done.

If you have measurable material loss that's a different scenario and would need specific data to answer.

dj

 

[LakeShark]

@dLj thanks for your help. Unfortunately it looks like I might be in for a little battle on this one. The response from the manufacture and the electroplater is basically we don't know it just happens sometimes and we ship it anyway. my concern is that there are 4 tubes for the motor mount support and only 1 of the tubes shows the marks. Also the marks surround every single weld on that single tube.

I agree that any comprehensive analysis is impossible on an Internet forum but I just don't want to make a big deal out of something that is not a big deal to begin with.

Is this a battle worth fighting?

 

[capta]

It looks to me that the mixture and/or scope of gases was wrong during welding. This means that the weld can be contaminated by oxygen, nitrogen, and other gases, causing it to be weak and porous. The finished weld may also have pinpoint holes, a defect known as porosity. Shielding gas acts as a blanket over the molten weld puddle, keeping atmospheric contaminants out.

 

[garymalmgren]

Is that chrome plated?
The second photo of the weld filling in a hole certainly looks plated.

gary

 

[LakeShark]

Is that chrome plated?
The second photo of the weld filling in a hole certainly looks plated.

gary

I believe it's stainless so no plating?

 

[dLj]

@dLj thanks for your help. Unfortunately it looks like I might be in for a little battle on this one. The response from the manufacture and the electroplater is basically we don't know it just happens sometimes and we ship it anyway. my concern is that there are 4 tubes for the motor mount support and only 1 of the tubes shows the marks. Also the marks surround every single weld on that single tube.

I agree that any comprehensive analysis is impossible on an Internet forum but I just don't want to make a big deal out of something that is not a big deal to begin with.

Is this a battle worth fighting?

Electroplater? Likely electropolishing.

The battle - is it worth fighting... have you paid for these yet?

dj

 

[LakeShark]

Electroplater? Likely electropolishing.

The battle - is it worth fighting... have you paid for these yet?

dj

your correct on the electropolishing and yes sir its been paid, shipped, and delivered. Approx a $500 mount all in.

 

[dLj]

your correct on the electropolishing and yes sir its been paid, shipped, and delivered. Approx a $500 mount all in.

You don't have much of a leg to stand on then unless you can get it professionally examined AND it is found to have a serious defect.

Right now you only have a small area that will have a greater tendency to rust.

Looks like quite a lot of work for $500... I'd say you got a good price.

I think I'd ask the manufacturer nicely if it would be possible to polish out those marks given they will be more prone to rusting. See what they say. Are they close to you?

Are you sailing in fresh water? If so, it's probably not much of an issue..

dj

 

[thinwater]

Not that unusual. That white is at the edge of the heat affected zone. It was probably many colors before passivizing and electropollishing. It also looks like the heat was a little too high (undercutting most visible in image 4), the drag angle was too high, and that possibly it was stick welded. Pros can do better, and my welds look about like that (I used to inspect welds as part of my refinery work, and my welds always embarrass me, because I know how much I suck compared to real pros).

Not optimum, but what are you going to do? I see a LOT of undercut welds on railings at boat shows. Welding thin stainless is tricky, and takes skill and time. This is probably strong and if you treat it with citric acid once in a while, it should last OK.

(Undercut weld on new boat--not strong. Should have laid on another pass.)

 

[LakeShark]

@dLj & @thinwater thanks again for your help and the picture. Contacting the distributor I am going to be sending this mount back for a swap out with a different unit. In addition to the welding there were some rough grind marks on the mounts locking positions that could be an issue in the future. Hopefully everything will work out with the 2nd mount. Good news is that it's still winter in the north here so there's plenty of time.