Why not bronze?

[Walter]

But on a boat...HELL YEAH! And especially never used for anything below the waterline.

Sorry, but you are mistaken. While almost any metal will corrode, only metals with iron can rust. Rust is iron oxide. Brass is an alloy of copper and zinc. No iron, no rust

 

[chazrich]

My guess is that it would also be too heavy for many of our applications. Have you ever picked up a small bronze statue, versus one of about the same size in brass? I don't know the actual math, but I'd estimate its at least 3 times heavier.

 

[cmburch]

Well, rust or corrosion? I think we understand. Now we know not to use the word rust if no iron.

I found this on copper alloys
List of copper alloys - Wikipedia, the free encyclopedia

I do not know. They both seem pretty heavy. I use nickle? plated brass at work for gas valve cylinders. They are pretty heavy. Maybe confusing the thickness of artwork to a door knob, sink fixture, or bed posts. You are right though. Bronze is more dense. But only by a small fraction.

 

[muddiver]

Brass is easy to work and machine. Bronze is harder than brass and prone to fracture.

Scuba gear is usually not subjected to the same length and severity of immersion in sea water as boat fittings and through hull fittings, so it does not need to be as robust and corrosion resistant.

I am also not so sure that bronze will plate all that well like brass does.

 

[captain]

Brass is a bad choice for any application that will be constantly in saltwater. It is an alloy of copper and zinc. The saltwater will eventually consume the zinc.
Bronze is the first choice for all continuous underwater applications. It is a alloy of copper and tin, the tin is not affected by saltwater.

Stainless steel also has issues with crevice corrosion in continuous underwater use that can cause a failure of the fitting

If the integrity of the fitting is critical to keep the boat floating bronze is the choice

In the case of exotic metals such as titanium and inconel cost doesn't really justify it use in diving equipment that spend little time in the water.

 

[Akimbo]

Bronze is almost exclusively a casting alloy. Modern machining abilities and the high cost of copper are rapidly replacing bronze with 300 series stainless. Wrought Brass is one of the most machinable materials, is widely available in bar stock form, and plates well. All copper alloys corrode. Corrosion resistance depends on building a layer of copper-oxide on the surface, which is self-healing but is too thick for many dynamic mechanisms to perform reliably.

 

[Gilldiver]

In general a brass is an alloy of copper and zinc while bronze is an alloy of copper and tin.

Bronze is the most costly, doesn’t machine as well as a brass, and is subject to fracture and cracking.

Brass is a cheaper ally but is subject to a process called Dezincification in alloys with zinc percentages above 15% where the zinc is corroded leaving a hollow copper matrix. This photo is a microstructure of a brass rod from a carburetor that was on a wreck lost in Long Island Sound in the 1920’s. All of the zinc is gone leaving a very fragile copper rod.

There are high zinc alloys that contain zinc percentages of 30% but also have arsenic or tin added to slow or stop Dezincification such as Admiralty or Naval Brass.

What is used for SCUBA, I’ll bet it has a high % of scrap content as virgin metals are very expensive compared to recycled. As for Titanium and Stainless, the costs for machining these metals is much higher and bring a premium. Think about it, the cost of the brass used in your 1st stage is so much less then stainless and titanium that the cost difference more then covers the costs for the chrome plate.

 

[grouchyturtle]

.....it was meant as a joke, but now that you mention it, all the things you mention ARE commonly manufacturered in plastic for scuba gear. Plastic 2nd stages have become the norm, Apeks recently came out with plastic 1st-stages.....recreational BC's are chock full of plastic D-rings (especially the new lite-weight 'travel' BC category).....plastic bolt snaps are available......and plastic valves are widespread in dry-suits abd BC bladders/wings, for example.....come to think of it, I've never heard of a metal BC dump valve, for example.

So was my response.

Plastic first stage! No thanks. And d-rings and snaps just break. All those other things do have metal parts.

Sorry, but you are mistaken. While almost any metal will corrode, only metals with iron can rust. Rust is iron oxide. Brass is an alloy of copper and zinc. No iron, no rust

Oopsie!

Well in that case, it corrodes bad enough in a marine environment, that there's no such thing as a brass thru-hull.