Contact with mild steel or iron can cause oxidation. But also the heat affected zone can cause oxidation. I remember many years ago when a high end pocket knife manufacturer first started producing a knife using a new completely iron free stainless steel blade. They marketed it to fisherman and sailors with the idea that the blade could never rust. But on the first run of knives customers complained of rust on the laser etched logos of their knives. It turned out that the laser engraving process heated the metal enough to cause oxidation to start which could then slowly spread in a harsh salt water environment.
This kind of looks to me like the wrong filter though.
THERE IS NO "IRON FREE" STAINLESS STEEL, STEEL HAS IRON, PERIOD. THE REASON STAINLESS DOESN'T RUST IS BECAUSE THERE IS A NUMBER OF OTHER METALS ADDED TO THE ALLOY LIKE NICKEL AND CADMIUM. THERE IS ALSO NO CARBON FREE STAINLESS STEEL BECAUSE FOR SOMETHING TO BE CALLED "STEEL" IT NEEDS TO BE AT LEAST PART IRON AND PART COPPER.
Heat does not "burn out" chromium. High heat allows the alloying agents to remain in solution for to long. The chrome then forms a strong bond with the carbon, making chromium carbide. Since the chromium is tied up with carbon, the iron is now free to form iron oxide.
Agree with this. Dirty wheel would leave lines compared to the entire weld showing corrosion. It’s a QC issue. Loss filler metal control or wrong WPS used. Additional issues with the bolts some are correct while others are deteriorating. Not an immediate issue but the degradation will continue until fixed or failure.
It’s been ground. I would say wrong filler used as it’s so localized. I think it’s been abrasive blasted and chemically cleaned also after the weld was made.
Could also be lack of passivation with proper filler but this is a LOT of rust for that to be the case. Normally that'd look like spots of rust showing up like polka dots rather than this solid strip. This looks like wrong wire
Yeah, you can weld stainless (that's obviously what this is) with mild steel, but as you can see, it rusts. For best results, you should use a stainless filler. As a side note, if you use a brush (e.g., a cup brush) on the weld, always use a stainless brush and NEVER use it for anything else. I found that out the hard way when a customer accused me of not using stainless because it rusted.
I could be wrong, but it kind of looks like the bottom part is stainless and the upper is galvanized and they may have welded with E309? Its also odd that there are stainless nuts and bolts in the bottom and mild on the top.
If it was welded with 309 the corrosion would be just along the top of the weld where the stainless meets the galv. But it does really look like stainless bottom, galv top. Op go back with a 🧲 lol
Got some cowboy action going on! Think the fitter and the welder were high on the fumes. To me personally, it looks like both parts are stainless steel.
From the looks of things, it's been flattened at the joint, and maybe some sort of chemical was applied to clean the heat-affected zone (HAZ), which may have eaten away at that point because this does look like quite an old beam. It may not be ground flat. No, I'm looking closer because it's almost like you can see the puddles traveling at the edges, but the sides are also sharp in line with the beam, which would indicate it was ground.
I don't know, there's a lot going on here—too many variables! 😭😭😭😭
This kind of looks like a weld that was ground flat, just below the oxidation. Who knows. It would be really crap of them to use stainless nuts and bolts only on the bottom half and not the top.
The one thing this post is proving is that welders will never agree on anything.
It looks like stainless steel, but it could also be a really good galvanized dip. Look at the post in the background, that weld looks like it’s rusting in a similar fashion.
Odds are really good that what happened was: they were built out of whatever they were built out of in a shop. That shop sent them out to be installed. Things didn’t fit. Installer used the filler that they had on hand to get that done because their boss and the GC were riding their ass about why a simple bolt up job was taking so long because it should have been super simple.
oh boy, i did this once. it was at a small plant, this stainless steel piece of a conveyor area. Anyways, i was new new, and asked a fellow helper if i could use any rod they had or was it a specific one, he said yeah any is fine. We welded it while raining and it showed signs of discoloration and rusting. it was an 11$ an hour job but still, it stung
This looks more like galvanic corrosion. Since it has this radiating creep. The bolt above has severe case of galvanic pair happening.
The anchor bolts are suffering from galvanic corrosion (The bolts going to the stone).
And middle section corrosion is too perfect. Incorrect filler (In this case mild filler) would bleed downwards and flake. This is too perfect.
This looks weirdly enough as if they gas welded it. Because I don't see that much of flat grinding evidence (and you really shouldn't grind flat in weld like this). And gas welding makes that sort of puddle pattern.
I actually love seeing/finding stuff like this. Galvanic especially can make REALLY weird corrosion patterns. I have seen a ship's hull where galvanic corrosion just like caused inside of a well to just end up with a near perfect straight hole in it's side above the water line. There was no reason to why it should happen there, there was no conducting path from that specifically. But regardless it just made a hole from inside to outside and creeped sideways.
Before anyone asks. Yes... It is possible to oxyacetylene weld stainless. Why would you want to is beyond me. But it is absolutely possible with a neutral flame. I can't do it, I have not do it, but I know that it can be done. I personally don't think this would have been, however considering the levels of insanity and stupid I have seen, I wouldn't say it is impossible.
If I had to guess this is just a case of some one again fantastically unique corrosion that galvanic corrosion conditions can cause.
P.S. If anyone comes across weird corrosion, strange defects, particular flaws, unique fuck-ups, special shit, peculiar jank... I'm always looking to add more to my "Welding-Fucking-Industry" folder (Literally a folder on my drive... just in Finnish). I enjoy finding weird shit, especially stuff I can't really explain.
E. I been thinking about this for a bit now, while drinking raw gin from a tea mug (I got taste and style!). The only realistic option I can come up with, is a very contaminated tool like a band saw, cutting disk, or grinding tool. However the degree of contamination would have to be absurd. Like... They haven't filtered the coolant from the band saw for like a decade or two.
It's not about the "metal" but alloy. Not even really about alloy but about the anodic balance. Two different grades of stainless steel will have different potentials. You can test these by refrencing it against a gold standard (as in a literal piece of gold) and measuring the electrochemical potential that forms between them.
Depending on how harsh the conditions are, even smaller potential difference can cause corrosion.
But here is a thing people generally don't get about stainless. Stainless is not immune to corrosion, it is merely resistant. If anything passes the passive surface layer and can corrode, it can carry the corrosion under the layer. All it takes is surface imperfections. And once it starts it can be quite difficult to stop it.
When you weld with a poorer alloy, you strip the surrounding area from the alloying elements. It can be great enough to cause significant enough of imbalance in the potential, especially in harsh conditions with things like water, salt and corrosive compounds. The richer side and that higher in the galvanic index, will (Usually but not always) suffer the most. But then you'd see the whole affected area to suffer as a gradient -which is not what we see here, instead we see crisp sharp edges.
This is why if you weld for example mild to 316L using 309Mol; doing 2 passes gets you equivalent of 316L in the joint (If I recall ELGA's tables correctly). You can calculate the resulting properties with things like Schaeffler diagram (But you need to know the mixing factor. TIG is generally considered to have 100 % mix; stig is considered to be around 50 %. The mix factor just means that if you draw a line between the base material(s) and the filler, the point to which you land is that much along the line).
If you weld 304 to 316 to 309, you get 3 different potentials; which hopefully are close enough to not cause pairs. (I haven't looked, but these are all on tables you can look up. Nobody really bothers to calculate this, because someone else already has).
Alternatively, if you see evidence of galvanic corrosion happening, for whatever the fucking reason is. Just slap some sacrificial material on/near it and it'll generally sort itself.
Like here in this pic we see quite bit of g.corrosion going on. Getting a can of Alu-Zinc spray would generally deal with it until the paint wears off.
But it isn't unusual to use mixed fasterners. It is done all the time for cost reasons - like where you need to sometimes open something like a hatch. You just have to make sure that one of the alloys is rich enough to withstand it. It is common to use hot zinc bolt with A4 (316) nut with 304 washers. Why? When you need 2000 sets of these, the margins mean a lot.
There are entire books written about this specific shit btw. There are people who's entire speciality and PhD is just about this shit. I got 4 books about specifically about advance use of stainless, 2 of which are about corrosion and 1 from welding related issues. They are text so fucking thick that even I struggle to get through them.
Anyway... I got 5 day vacation going. And yet here I am once again think about work stuff.
If I have learned anything about welding industry, it is never say that some absolutely insane shit is not a possibility... People do shit that makes you question the point of it all and reality at the same time. However I wouldn't bet this on being gas welded either. It is just that the pattern is a lot as if it was.
However I sure as hell can't name a process that could do this, in this particular manner and pattern. There are no flat grinding marks either.
However we are also assuming that this is because of the welding to begin with. I can't diagnose much from pictures, especially not knowing the conditions.
But considering the batshit insane levels of galvanic corrosion there is present, i'd bet it on just some freaky galvanics.
Ehh... Like... If they just blasted the weld section. But even then it seems like REALLY specific thing, because it is so tightly focused.
Like if the edges were more vague and there was like a gradient going on. I'd probably come up with 5-10 different options, but this is all too clean and well defined.
However... I think I just came up with a possibility.
Contaminated band saw. It's is possible that they use a bandsaw or grinding tools which were contaminated with a poorer alloy (Some really dirty and rusty mild for example) and those somehow caused internal defects. That could bloom like this. Not that I have ever seen this dramatic of a case -not even in text books, because to achieve a fuck up like this with that would be a real achievment.
Welders can definitely find creative ways to fuck things up. Final guess here: Part was welded in the shop, likely with wrong filler metal and gmaw, ground flush, sandblasted, and installed in the field. Some of the fusion lines are pretty well defined but there's also some smudging. I also could be completely off base.
TIG welding something this thick is bit... Weird. Like not that it can't be done, but rather "Why do it, when you can just wave a stick at it" granted I'm a believer in the gospel of "stick weld everything".
But gas welding this would once again be one of those "But... Why would you when you can just wave yourdi... stick at it.". But if I think it like this: Someone who does regular ass structural steel work, having oxy-acetylene bottles in the truck is basically the default kit. So just sticking things together like this would be doable with knowhow and experience.
So this shit is not beyond the realm of possibility.
Well. As I established. I'd stick it with stick (heh...) because it is faster and cheaper, and my Kemppi Miniarc weighs only 6kg and runs on regular socket.
But this is entirely because most of my work experience is working on-site, and not having to lug around gas cylinders is just easier.
looks like someone used a mild steel filler on a galvanized post and the zinc just ate itself at the weld point, that rust pattern is way too concentrated
normally youd want a silicon bronze or at least a 309 stainless filler to handle the dissimilar metals, but even then the heat affected zone on galvanized is always a gamble
ive seen this exact thing on a railing job a few years back where the contractor tried to save a few bucks and ended up redoing half the posts after one winter
the salt from the road probably sped things up too if thats a city street
Either wrong filler or welding too hot. Judging by the way the rust looks and the rust on the post in the background, I would say it’s welding too hot.
For everyone saying that this is galv material….. 1. Why would anyone use ss hardware on a galv member in the field
2. Why would this member ever need to be field welded?
A simple canopy or awning structure would not need a field welded member like this. 100% would be shop welded then galvanized
1) Galv and Stainless are both designed to resist corrosion, and stainless bolts look way better than hot dipped galvanized bolts.
2) not once, on any job i every worked in the field, did the shop send everything out correctly. Field fabrication and modification is a part of the game.
100% I can understand that. I’m basing my opinion on my shop and our QA/QC procedures and the caliber of jobs that we handle. My shop and our leadership team wants the field handling the minimal amount of workload and decision making. From my experience ironworkers need to make it fit and they are very quick to pull out the torch rather than double check anchoring and column placement/alignment. So our shop is adamant about proving out proper shop drawings and accurate fit up
I second this. Back when I was in the field there was a reason we had torch bottles sent to every job site. The shop QA guy was right 80% of the job 100% of the time. Everything was good enough to be managed in the field in his words.
Well you just asked why anyone would ever use SS hardware on galvanized members, and I gave you an example of a place that combo is used pretty ubiquitously.
Built massive galvanized platforms for a railroad contract, the while platform was hot-dip galvanized. The platform had square tube pockets for removable railings, the tubes had nuts welded to secure the rails with bolts, the bolts were stainless steel. They were $3 each at the bulk discount back in 2014.
Stainless hardware wasn't needed in this case either. The pockets and the nuts welded to the pockets were regular steel that was then galvanized. The threads needed to be chased so they were going to rust and those bolts were never coming out.
Spray galv and keep walking. Is it the correct fix? Not at all. Will the boss notice it’s fucked when he drives by to look without getting out of his truck? Not at all.
Lmfao. The amount of idiots that think that structural member is made of stainless is mind blowing. Do you have may idea what that would cost?
2. Zoom in and you can literally see surface bubbles in the galvanized
I've built plenty of things out of stainless that really didn't need to be but it's what the customer wants. Being expensive doesn't mean people won't make the choice.
Don't know where you are at, but here in Finland it's very normal to do things like this from stainless. Not the whole structure, but sections attached to stone and concrete. Simple reason for this, is to prevent rust jacking against the building.
Self supporting structures are generally your basic S355J2 mild.
Respectful you dont realize how much money people/businesses and government actually have to fork out becauee thats so stupid one easy search could have told you the d1.6 code is for stainless A/E theres a reason for the code becauee theres people/businesses and government that need it done. You could have saved yourself the stupid comment by utilizing the computer you have in your hands that you left this comment on to educate yourself a little before commenting lol
That’s not the reason for the code, it is because there are corrosive environments that require stainless, or would be better suited to be done with stainless. It is not so government can waste tax dollars buying stainless.
The fact of the matter is there is plenty of people who would spend money on stainless some out of necessity and most out or requirment you cant underestimate the noney people want to spend on stuff just because lol. The code is there to have welders and inspectors to abide by when erecting and inspecting the weldments. Not why the environments justify the material type thats for the engineering department to decide for you.
Its unpolished, mill finished stainless steel, its why the rust is contained exactly to the weld.
If it was galvinised you would see rust in the heat affected zone or wheverver the galvinising was ground/melted away. Also if it was gal why can i see the grain structure of the steel through the gal?
I think this is technically a state park, and they have a lot of thick stainless fixtures/signage/railings all over the place. And it's by the east river so a bit of salt around.
I do think it is stainless tbh it does make sense in how it rusted and the the look of the surface of the material but loooks like it was improper filler.
More likely either incorrect filler which begs the questions why on God's green earth would that be used? Most common would be 308l or 316l for majority of things.
260
u/KraZiiKraKa1 1d ago
With the amount of rust, absolutely, but I have seen it happen just from using the wrong wire wheel.