Locating Pins - C-1144 Black Oxide vs 440C Black Oxide 2

[GASSMAN]

Hi,

I'm looking to have some diamond nose locating pins made. These pins will be aligning two anodized aluminum parts. Besides corrosion resistance we are also concerned with a shear fracture, due to the brittle material.

I'm wondering if C-1144 with black oxide finish would be sufficient or if 440C stainless with black oxide finish would be worth doing.

The quote I received said they can get a Rockwell hardness of RC 60-64 for the C-1144 and RC 56-60 for the 440C.

Thanks for any suggestions you can give me.

 

[TugboatEng]

If they're just aligning, why are they carrying load? Aluminum will plastically deform long before such a hard pin shears. Black oxide coated 1144 steel will only temporarily resist athmospheric corrosion.

 

[GASSMAN]

They're aligning and carrying some load as well. There's a Clampco V-band clamp holding the two mounting flanges together, so some of the load is carried by the clamp.

I was thinking about the 440C, but another engineer here is concerned about the tensile strength vs. the C1144 after hardening.

 

[EdStainless]

As TBE said, the 440C is still three times as strong as the Al that it will be mated to.
If you want some corrosion resistance then go with the 440C.

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P.E. Metallurgy, Plymouth Tube

 

[GASSMAN]

Sounds good. Thanks, guys!

 

[Compositepro]

I believe that black oxide is porous and requires oiling to actually provide much corrosion protection.

 

[GASSMAN]

Yes, our pins are heavily greased before assembly.