Australian 316 stainless - the good, bad & ugly

[Cadence]

Originally Posted by Cheechako

You gotta watch where you get it and what you get in the US too! Some of the Ace stuff is pretty good, a lot better than Lowes for sure. Not sure if all Ace's are the same or not. There are Screw supply houses for commercial customers... they may be the best bet.

You can get the commercial suppliers to work with you. Just don't say I need 50 screws say I need 500 or maybe 1000. They will count them by weight. Ace I found had a good product, just pay a little more if you only need 50. Lowes deck screws are 305 stainless.

[Wotname]

FWIW, for SS fasteners I prefer to buy the product in the original manufacturer's packaging from either a commercial/trade supplier or a smaller but respected local chandlery. Yes, you do have to buy larger quantities but when have you ever had enough fasteners . The owner of the one I used in Perth had built his own cruising multi and the local one here is also involved in building. I think this helps.

Almost got caught out when buying some 316 SS stock. I had ordered several lengths of 50x6 mm flat bar in 316 from a major well known Aussie steel supplier and when I was loading it, I noticed the manufacturer's coding sticker still on one piece. I couldn't "decode" the code but as it contained this bit "-304-" inside a whole pile of numbers, I was suspicious. Took a photo of the code and when back to the salesperson and asked him what it meant. It took him a few minutes and a few phone calls before he proudly tells me all the information in the code - including of course the fact the material was 304 grade.

He was a little red-faced to realise he had tried to sell me 304 instead of the the 316 I had ordered.

I now ask for a certificate of compliance when buying stock. Some suppliers aren't interested but other's are happy to oblige. I guess it is no guarantee but it must help a little.

[Reefmagnet]

Most austinetic stainless steels will become magnetic if worked, which also makes them harder, hence the reason why drilling can be difficult, yet so can galling in the same material. A magnet is only good if you test unworked material. The big problem as I see it is that it is easy to substitute the cheaper 304 grade, or other grades, which is impossible to differentiate with 316 unless you do a spectrographic analysis. When it comes to magnetic 400 grades there are two types. There's ferritic which is soft, cheap to produce and work and used for things like automotive trim and there's hard martinsitic that requires more processing and is used for stuff like knives and cutlery.

[Alii]

Coops & Cadence -

For fasteners we were working with commercial suppliers, first-name basis over a period of 10 months, usually buying full boxes of 100-200. Most things came in the original box. Most purchases were through Maryborough Bolt, special orders from two catalogs, James Glen and another I can't recall the other name of just now (started with C?). Items we couldn't find there we would source from a large trade supplier on the west side of Hervey Bay which also carried tools, Sika, etc.

Nothing from Bunnings or Mitre10 or Ace. I checked some items with a simple magnet, have never heard of a "rare earth" magnet before.

Now that you've got my brain working, I realize that the M10 eye bolts installed at the base of the mast have proven to be EXCELLENT.

Yesterday after starting this post, in an entirely unrelated conversation, an Australian surveyor told me that he was seeing so many failed skin fittings in 1-2 year old boats that he made some calls to ask the distributor whether they knew what kind of bronze they were selling. Admission: no, no certificates. They could ask the Chinese manufacturer to provide a certificate, but knew the plant would cook up a special batch just to certify and that would tell them nothing about the actual products imported.

[Seymore]

(Passivated) type 316 stainless steel is type 316 stainless steel. I mean to say that's the alloy you want for boats, nothing to it, and nothing else will do.

It's simple. Get a big magnet from an industrial supply place, like McMaster-Carr in the US McMaster-Carr When you get supposedly 316 screws or parts, test them with the magnet right on the salesperson's counter. If the magnet disturbs them at all, sneer and walk out, period. Like a previous poster, I found only a big rare earth magnet works and, yes, it works very well.

In our league, only good 316 SS parts are not paramagnetic, meaning they won't respond to a magnet.

304, 400 series, 18-8 are unsuitable for our boat work, they rust quickly as the OP found, and they are paramagnetic, meaning they do respond to a magnet. They're good for making flatware, hence the term 'stainless steel' because they don't tarnish like silver.

Notice that I said PASSIVATED 316 is the alloy we want. When you cold work 316, the cold worked parts will corrode like 304, so cold worked 316 (ACTIVATED 316 SS) is unsuitable for our boat work. That's OK, sort of, since ACTIVATED 316 IS PARAMAGNETIC, so it responds to a magnet and we can spot it a mile away. So once again: Nothing to it, if the magnet disturbs it at all, sneer and walk out; nothing more, nothing less. Period.

Activated 316 SS is passivated by passsivating it in concentrated nitric acid. Do not you get into passivating stainless steel in nitric acid unless you have a fume hood and know how to use it.

I get my 316 SS stuff from McMaster-Carr and Fastenal McMaster-Carr and Fastenal – Industrial Supplies, OEM Fasteners, Safety Products & More in the US. I've had good luck with them. When they say it's 316, it has almost always been 316 and non-paramagnetic, and it stays bright and shiny for years on the boat. The local Ace Hardware, Home Depot and Lowes stock only 304 fasteners and they say so. The US chandleries are into stocking 304 fittings and fasteners and blithely saying they're as good as 316. They warrant a big SNEER. The OP has run into people and chandlers who have misrepresented 304 and all as 316, which is an even lower step on the ladder of merchantability.

The textbooks, handbooks and detailed references will talk of some 316 being attracted by a magnet and stuff like that, because they are and they have to say so. If you have a PEng after your name you'll know how to handle that stuff. Us here, however, for our boats in salt water, you just never mind that ********. You just test it with that big rare earth magnet and if the part on the table does not wiggle at all, you're all set, you've got good 316 parts, nothing more, nothing less, easy peasy.

[model 10]

Seymore; In such a long post you have left people thinking that passivation and pickling are the same thing and did you suggest that passivation will remove magnetism?
You may want hot Nitric acid for pickling, you don't need it for passivation. There are other choices.
Polished and Passivated 304, welded or worked can survive but I find it up near wood in the care needed to be kept nice.

[chala]

Originally Posted by Alii

Four years ago we refit in Queensland and went to incredible effort to buy fasteners, plumbing parts, etc. made of quality 316 stainless.

You must have been extremely unlucky or have used rusty tools when installing your SS. I have had no rust mark, stain or pitting out off 42 kg of fasteners from James Glen, Ajax or Bremick, 779 kg of 316 and 325 kg of 304 from Atlas Speciality Metal.

Originally Posted by Wotname

I now ask for a certificate of compliance when buying stock.

The way to go.

[Alii]

Whew, how can a full-time cruiser stay so organized as to retain and find this kind of paperwork years on?

Everyone who has read this thread in full will be granted a PhD in metallurgy from the University of Zen.

Of course, this discussion has focused on my fasteners. Not that we need to get into the valves, street elbows, and other beefier hardware that has also disappointed. Or do we? These were purchased from Blackwoods, special ordered through Davies (pumps and irrigation chain), or special ordered through the yard from BLA. I do recall in at least one instance refusing to accept what BLA provided.

The 2 street elbows in my original post came from Davies. I've just dismantled the part of the boat that lets me inspect the third elbow that came in that very same order, installed at the same time with identical methods, and it is fine. Spotty QC?

I can't claim that my tools were surgically clean but certainly not rusty, and that theory wouldn't explain the deterioration of these non-fastener types of things.

[Cadence]

Originally Posted by Alii

Whew, how can a full-time cruiser stay so organized as to retain and find this kind of paperwork years on?

Everyone who has read this thread in full will be granted a PhD in metallurgy from the University of Zen.

Of course, this discussion has focused on my fasteners. Not that we need to get into the valves, street elbows, and other beefier hardware that has also disappointed. Or do we? These were purchased from Blackwoods, special ordered through Davies (pumps and irrigation chain), or special ordered through the yard from BLA. I do recall in at least one instance refusing to accept what BLA provided.

The 2 street elbows in my original post came from Davies. I've just dismantled the part of the boat that lets me inspect the third elbow that came in that very same order, installed at the same time with identical methods, and it is fine. Spotty QC?

I can't claim that my tools were surgically clean but certainly not rusty, and that theory wouldn't explain the deterioration of these non-fastener types of things.

[Seymore]

Originally Posted by Alii

Of course, this discussion has focused on my fasteners. Not that we need to get into the valves, street elbows, and other beefier hardware that has also disappointed. Or do we? These were purchased from Blackwoods, special ordered through Davies (pumps and irrigation chain), or special ordered through the yard from BLA. I do recall in at least one instance refusing to accept what BLA provided.

The 2 street elbows in my original post came from Davies. I've just dismantled the part of the boat that lets me inspect the third elbow that came in that very same order, installed at the same time with identical methods, and it is fine. Spotty QC?

In my honking great post I addressed fasteners, valves, street elbows and other beefier hardware that's claimed to be made of 316 SS. It's all the same, if it's claimed to be 316, if a magnet disturbs it, it'll rust.

I think something. Get your stuff directly from China, from Chinese mail order chandleries and industrial suppliers. Davies, Blackwood, BLA and all have no respect whatever for you or Australia. The Chinese are very competent merchants. Perhaps Gord May can dig up some web sites.

[KASHMIR]

Many people don't realise the importance of removing contamination from the surface of stainless steel. I ran a stainless manufacturing company for many years and we always used #304 grade and never had problems. #304 is not supposed to be the most suitable for seawater environments but I only make things for my boat from it. It has to be cleaned very thoroughly after fabrication and it does get a small amount of surface rust after a few years so I just go over it with scotchbrite and oxalic acid. This brings it up like new again.
Just using normal mild steel spanners will contaminate SS fittings.
Interesting fact is that most Ronstan fittings fittings are made from #304.

[Alii]

Seymore - You are absolutely right about the scope of your masterly post. Didn't mean to suggest otherwise.

So any non-SS tool can muck up a 316 fastener? Haven't had that problem with the Swedish stuff using the same tools.

I cleaned everything being reused before reinstalling but not brand new items.

[Jim Cate]

Please explain how use of a steel tool can alter the metallurgy of a s/s fastener. I can imagine that some minor transfer of material could happen (although the tool is likely much harder than the fairly soft s/s fastener) and that material could oxidize and cause discoloration... but I don't understand how it can wreck the non-surface structure.

I await knowledge.

Jim

[model 10]

Steel tools damage the oxide coating and then contaminate the surface so it can't form an oxide coating again. Then the rust grows.

[Kenomac]

Jim,

By "work hardening" stainless 316, the molecular structure of the metal becomes altered, making it magnetic. Work hardening is the mechanical manipulation of the metal examples such as Hammering or cold working the metal to make it thinner etc.