Converting to and Fabricating Bronze Chainplates / Tangs

[wolfenzee]

Originally Posted by Matt sachs

I just bought 2 inch flat SS316 stock 3/8 inch. I paid $7 a foot. As far as working it, use the correct drill bit, go slow, flood it with coolent and it works fairly easy. The 15* bend shouldnt be a problem with an anvil and a strap of leather to protect the finish. (or a press) Getting the holes drilled in the right place to match the hull might be the hardest part of the job.
I love the look in post #25 great job. It looks like it matches the rest of the rigging better that the SS would have.

If we are going by looks....most of the visible metal on my boat is bronze, with a bit of brass, my life line stanchions are the only visibly stainless other than standing rigging.

[wolfenzee]

Originally Posted by blahman

Hello all,

onlinemetals.com offers Aluminum Bronze, alloy C95400, in 3/8"x2" and 1.5". The total cost for all of the bronze I need (12ft of 2", 6ft of 1.5") would be about $300.

I have seen people say that aluminum nickle bronze and silicon bronze are good choices for use around the water. However, I'm not sure about "aluminum bronze". It's specifications are thus:

Aluminum Bronze, C954 Minimum Properties Ultimate Tensile Strength, psi 85,000 Yield Strength, psi 32,000 Elongation in 2" 12% Brinell Hardness 170 Chemistry Copper (Cu) 83.0% min Iron (Fe) 3.0 - 5.0% Aluminum (Al) 10.0 - 11.5%

As opposed to silicon bronze:

Silicon Bronze, C655 Minimum Properties Ultimate Tensile Strength, psi 85,000 Yield Strength, psi 55,000 Elongation in 2" 20% Rockwell Hardness B90 Chemistry Copper (Cu) 97.0% min Iron (Fe) 0.8% max Manganese (Mn) 1.5% max Nickel (Ni) 0.6% max Lead (Pb) 0.5% max Silicon (Si) 2.8 - 3.8% Zinc (Zn) 1.5% max

Does anyone have experience using aluminum bronze; I want to make sure it is a strong enough metal. I'm not sure if "32,000 psi" for yield strength is enough compared to silicon bronze's "55,000 psi".

Thank you for your time!
Aaron

I do know the local foundry here uses aluminum bronze for chain plates, and aluminum bronze bar is more easily accessible to me. I have been told to use silicon bronze, but not suggested in preference to aluminum bronze, just from someone that prefers it.
If I did go with aluminum bronze I can get 0.357" (3/8) thick x 1.5" wide x 26" long x six chain plates for $277 including shipping also from onlinemetals.com, they just don't have silicon bronze in bar form.

[seandepagnier]

I replaced my shroud chainplates with aluminum bronze, and I have sailed across the pacific from california to new zealand. I am happy with them and I am pretty sure they will last as long as the boat. The bolts are silicone bronze.

The think to keep in mind, is there is forged and cast bronze. Silicone bronze is usually forged which means you can put a bend in it. Aluminum bronze (like mine) is usually cast which means if you bend it, it greatly weakens it, and bend it too much and it will break. Because of this I only did the shroud chainplates which have no bend in them and are attached to knees and bulkheads. The foreand aft chainplates have bends and are stainless.

[wolfenzee]

Originally Posted by geckosenator

I replaced my shroud chainplates with aluminum bronze, and I have sailed across the pacific from california to new zealand. I am happy with them and I am pretty sure they will last as long as the boat. The bolts are silicone bronze.

The think to keep in mind, is there is forged and cast bronze. Silicone bronze is usually forged which means you can put a bend in it. Aluminum bronze (like mine) is usually cast which means if you bend it, it greatly weakens it, and bend it too much and it will break. Because of this I only did the shroud chainplates which have no bend in them and are attached to knees and bulkheads. The foreand aft chainplates have bends and are stainless.

It is "work hardened" which means cold bending will stress it, to bend it requires heating and cooling by someone who knows what they are doing. My boat has channel boards so I have to bend it 30degrees, then back 30degrees, plus a few.
if I buy 954 bronze bar it will cost me $277 including shipping for 6 if I have the local foundry make them for me it will coat over $1200 for 6