Rust/corrosion on 3yo SMP Diver 300 bracelet

barra king

G’day all. I just noticed a sizeable rust-coloured mark on the bracelet link of my SMP (purchased new in 2017). Given that it’s stainless steel, I figured it was just a buildup of some grime...that is until I gave it a good wash and had another look. I was able to remove the rust stain which had extended outward from the point of corrosion on the polished link to the brushed surface adjacent to it, but a closer examination revealed that the leading edge of the polished link has corroded (no longer a smooth leading edge) and a rust-coloured, irregular surface remains. Interestingly (to me), I noted that the other three links on both sides of the watch case had a small degree of rust in the same location. My question is, ‘Is this a common thing with the SMP Diver 300?’
I possess a 40 yo sea master and a handful of other pieces that are rust free, so it is mildly irritating to find this on a quality time piece. The watch is my ‘daily wear’ and apart from the usual perspiration a watch is exposed to, it has not been exposed to anything else chemical or otherwise. The attached photo is of the watch after I cleaned it.

Matt87

It is very very strange!! I've seen at work during few years hundread of Seamaster 300 Pro and i never noticed anything like rust or corrosion... How is that possible?

imranbecks

Here it is on mine on the side of one link. Its a very small speck. Can be scratched off, but will appear again after a few days... It has been that way for a couple of years now I've noticed. Odd.

Matt87

It very strange indeed!!! Never seen or heard about corrosion on a 316L steel... As someone said before, it could be related to swimming in salt water or diving in it without washing off the salt afterwards with fresh water but it should have happened a lot of times to corrode the omega stainless steel...

imranbecks

But like i said before, i always rinse it with fresh water after a swim. I would imagine it'd be worse than that speck if I didn't.

Matt87

Very True... This is another thing to consider!! The whole story is very strange... Could it be related to impurities in the stainless Steel alloy?

imranbecks

No idea. I did a double check of the watch just now, looking through the links and all the nooks and cranny, all clear. The only rust spot is the one pictured on the side of the link. The rest of the watch is fine.

Donn Chambers

Since no one seems to want to read the PDF I linked to above describing the chemistry, I’ll attempt to paraphrase.

1. What makes stainless steel rust-resistant is the chromium in the mixture. When exposed to air, it forms a chromium oxide layer that is resistant to rust. If a process reduces the amount of CrO in any area, or covers it, then rust can form.

2. If the chromium is not uniformly distributed in the steel matrix, there can be small areas where there is little chromium, and less capability to form CrO. In this case, it is a deficiency in the alloying process. This may or may not be the case in these examples.

3. Another common cause of rusting is When a piece of high-carbon steel or iron is rubbed against stainless and leaves a scratch and some of the high carbon material behind. That will then rust. Consider leaning over an iron railing on a balcony and the bracelet makes enough contact to leave a scratch. You’ve probably transferred non-stainless material as well, which will rust. In this case, the stainless material underneath will form CrO and not rust, only the surface material will rust.

Evitzee

No, it's not a defect. The article explains how rust on SS is possible.

Donn Chambers

Have you regularly worn the watch is salt water? Did you thoroughly rinse it off afterwards? Because regular exposure to salt water will corrode even stainless steel and allow rust to form.

Chlorine is swimming pools will have a similar effect. A lot of people with steel dive watches don’t realize this.

Donn Chambers

Have you regularly worn the watch is salt water? Did you thoroughly rinse it off afterwards? Because regular exposure to salt water will corrode even stainless steel and allow rust to form.

Chlorine is swimming pools will have a similar effect. A lot of people with steel dive watches don’t realize this.