Titanium Chain Plates

[Storm]

Thanks Stumble

[billknny]

What advantages does Ti have over bronze for most chainplate applications?

It is lighter of course, but for 99.9% of boats the difference can't be significant down low.

It is shiny and stays that way... so I guess if that is important...

But bronze is similar in strength to stainless in the same dimensions. Corrosion is not an issue. And I don't know of any long term fatigue issues.

With a little care, bronze can be worked by pretty much anybody with a bit of knowledge. The overall fabricated cost is similar to stainless. When I have looked at fabricated Ti vs 316 stainless they are NOT that similar in cost.

For the typical cruising boat why Ti? Cache'?

[Storm]

Originally Posted by billknny

What advantages does Ti have over bronze for most chainplate applications?

It is lighter of course, but for 99.9% of boats the difference can't be significant down low.

It is shiny and stays that way... so I guess if that is important...

But bronze is similar in strength to stainless in the same dimensions. Corrosion is not an issue. And I don't know of any long term fatigue issues.

With a little care, bronze can be worked by pretty much anybody with a bit of knowledge. The overall fabricated cost is similar to stainless. When I have looked at fabricated Ti vs 316 stainless they are NOT that similar in cost.

For the typical cruising boat why Ti? Cache'?

I looked at bronze and wanted to go that way. The cost was similar to stainless and I could drill the material myself and no need to polish like stainless. I was planning to go with silicon bronze. The problem I had is that I did not feel comfortable with the material source. A lot of bronze is coming out of China and I did not feel comfortable with the quality control. The other problem I had was with the material, it was bronze but was is rolled sheet, wrought, or cast? I think there are big differences in the strength. Also, I could not find bar for the dimensions I needed. Therefore I need to have the chain plates cut from bronze plate. The cutting opened up another can of worms. I just did not have a good comfort level with bronze, and some of that is due to my lack of knowledge on the types of bronze material out there. the other problem I found is the strength numbers for bronze seem all over the map. If I look up strength for silicon bronze, I can find some similar to 316 stainless and some well below.

[009hnoor]

This works out to about 55% of the UTS. Or about 60% of the yield strength. In other words, assuming a safety margin of 2:1 titanium parts don't have a fatigue limit in marine environments.

[http://g4g.pl/forum/sprze]

I haven't had well experience yet, so I appreciate your advices. I greet you

[Stumble]

Originally Posted by Storm

I looked at bronze and wanted to go that way. The cost was similar to stainless and I could drill the material myself and no need to polish like stainless. I was planning to go with silicon bronze. The problem I had is that I did not feel comfortable with the material source. A lot of bronze is coming out of China and I did not feel comfortable with the quality control. The other problem I had was with the material, it was bronze but was is rolled sheet, wrought, or cast? I think there are big differences in the strength. Also, I could not find bar for the dimensions I needed. Therefore I need to have the chain plates cut from bronze plate. The cutting opened up another can of worms. I just did not have a good comfort level with bronze, and some of that is due to my lack of knowledge on the types of bronze material out there. the other problem I found is the strength numbers for bronze seem all over the map. If I look up strength for silicon bronze, I can find some similar to 316 stainless and some well below.

One of the issues is that siliconised bronze has a much lower fatigue limit that G5 titanium. It doesn't mean it can't be used and last close to forever, but it has to be designed to compensate. 87600 (low zinc siliconised bronze) has a yield strength of 32ksi (vs 110ksi for G5), and a fatigue limit of 22ksi (vs 60ksi). So the bronze part needs to be roughly three times the dimensional area as the titanium one to match the same design specs.

When you price a part this way the titanium one is likely to actually be cheaper than the bronze. While titanium prices have been plummeting for the last decade copper prices have shot up dramatically thanks to its use in electrical wiring.