My knowledge on metallurgy is very limited. I'm going to a CNC shop tomorrow to have a pin made but I'm unsure of the material. I would like the part to me light, i would like it to have good corrosion resistance. the estimate on the part is $370USD which is way higher than i originally planned. then again I'm in the UK now so i don't really have much of a choice. what material would you recommend for this pin?

 

Being that it is a critical component, I would suggest sticking with 304 stainless.
Alumn would be lighter. But for such a small part, you are not saving that much weight.

[edit] If this is for bicycle, then you might be ok with a 6061 Alumn.

 

304 stainless and you never have to worry about it.

 

ive been doing some more research and am looking at 7075-T6. I'm sure my math is correct but please do correct me if you see something. Comparing EN24 & 7075 it looks like the 32mm should give me 125K & 102Kpsi Yield respectively. I don't know what the stock pin is made of, but it is hollow so I cant see using 7075 as a problem given its a solid piece.
The machine shop I'm going to in the morning also does anodizing so i think I'm set.

 

YES agree!!!! The piece is hollow due to bending loads. The center of a material piece is useless weight when it comes to a bending load since foces are only concentrated on the walls.Bending cycle loading on aluminum has a limited amount of cycles. Steel is almost infinite. Aluminum is also weaker at tensile loads, but I would worry about its fatigue. Since this is a piece on a bike that will see both types of loads, I would go steel.

Dont play with your life! If you want it to last and be safe go steel. If this is a race bike and the piece will be constantly checked for fatigue cracks or you have research behind trying its weight/strength then go AL.

 

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