I did a quick search of the forums for info on titanium screws but didn't find anything.
I was searching for a source of 5/40 stainless oval head screws, for a Penn 349 project, and came across this site:
http://www.titaniumbolt.org/products/ based in the US.
Their minimum order quantity was too high for my needs, but if some enterprising gentleman in the US would buy some, they could be divided up and sold to interested parties :)
I was specifically looking for 5/40 1/2" and 5/8"
The advantage with titanium is no salt or galvanic corrosion compared to stainless or plated brass. Let's see what you guys think.
Titanium is high on the nobility scale and tends to play rough with lesser metals when exposed to saltwater.
That raises a more general question Lee. Is it better to have the part or the fastener more noble? The fastener is cheaper to replace if it corrodes but could become frozen in place and difficult to remove. The part is more expensive to replace if it corrodes.
I just buy stainless and brass screws at the hardware store for tinkering. But they only go down to 4/40 and I'd like one size smaller.
-steve
Best is all metal parts are the same alloy. Aluminum and Ti is bad, stainless is better. Part of the problem is fesing of parts too.
If I had to make a choice I would use the more noble metal for the frame.
A titanium framed 349 would be sweet ;D I can't see it happening soon ;D ;D ;D
That would be nice.
Titanium is not going to happen it's hard to machine and not cost effective. Most all titanium comes from Russia and is hard to process. So to make a frame out of it would cost allot of money. No one would buy it. Casting it would be the way to go if you were crazy enough to try.
Mike
Quote from: oc1 on August 22, 2017, 07:19:31 PM
That raises a more general question Lee. Is it better to have the part or the fastener more noble? The fastener is cheaper to replace if it corrodes but could become frozen in place and difficult to remove. The part is more expensive to replace if it corrodes.
I just buy stainless and brass screws at the hardware store for tinkering. But they only go down to 4/40 and I'd like one size smaller.
-steve
Here is a good article on this exact topic: http://www.corrosion-doctors.org/Corrosion-Forms/area-effects.htm (http://www.corrosion-doctors.org/Corrosion-Forms/area-effects.htm)
"Another important factor in galvanic corrosion is the area effect or the ratio of cathodic to anodic area. The larger the cathode compared with the anode, the more oxygen reduction, or other cathodic reaction, can occur and, hence, the greater the galvanic current. "
(Cathodes are more noble)
So...
Since titanium is more noble than stainless it would actually enable more corrosion in the aluminum (which is less noble than both), and the greater the ratio of stainless (or titanium) to aluminum, the greater the potential for galvanic corrosion. The corrosin will occur mostly in the anode, which in this case is always the aluminum. I guess you could make an argument that it is better to have the hole than the fastener corrode, but either way, you are screwed ( :) sorry)
Think about what this means in terms of corrosion potential with larger parts that might be more noble, such as bridge plates, stainless reel posts, etc.
If you have a barrier between the metals, it will prevent the corrosion. Marine grease is what everybody here uses, and it works pretty well, but it does not bond to the surfaces at all, so there is always the possibility of losing part of the barrier as the grease gets squeezed out or rubs off. There are special coatings made exactly for the purpose of preventing galvanic corrosion in fasteners. Maybe useful for aluminum reels with stainless screws that may not get a regular full service?
-Jurelometer
You would have to coat the screws with a grease that would insulate and prevent electrolysis. Like super lube.
How about Anti-Seize compound?
Duralac is used for marine/aviation applications where dissimilar metals are mated. Good explanation here:
http://www.ybw.com/forums/showthread.php?375481-How-does-Duralac-work&s=9bedbc4ba80bf6498c56d5ddc655ea0c
but it is like (as the name suggests) dries like "laquer" and dries hard, so removing screws can sometimes need some work.
cheers
Steve