Corrosion resistance 1

[prdave00]

I have two choices for some shafts that some linear bearings will run along. The parts will be immersed in a saline solution at 98 deg F for 14 days. I have both 440C and 17-4 hardened shafts readily available. Any guesses on whether either I should expect corrosion of either stainless steel alloy. If so, is one material more prone to corrosion than the other in this environment.

I quickly perused a bunch of galvanic series charts, but didn't find any listing 440C and 17-4 stainless in comparison to one another.

 

[TVP]

In general, 17-4 will do better than 440C, but it depends on the aging temperature. Neither is optimal for this environment. The 440C will likely have rust and pitting after several days exposure.

 

[EdStainless]

The 17-4 is the best bet.
What are the bearings?
They may be what corrodes the worst.

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Plymouth Tube

 

[prdave00]

I feel foolish for admitting this, but the bearings have 440C stainless steel balls in an Acetal housing. Then there are the restraining rings that are carbon steel (until I can swap them out for a stainless steel ring). I have my fingers crossed that corrosion will not adversely affect function for this "short" period of time!

 

[JamesCKelly]

A steel with much better chloride corrosion resistance than 440C is Crucible's 154CM. Nominal 14%Cr 4%Mo 1%C

 

[unclesyd]

I would suggest using either Aqualoy 22 or Aquamet 22 in lieu of the materials in the OP. If need be the 17/4 material aged at 1125F for 4 hrs would be the better than the 440C.
Even though 17/4 is, Aqualoy 17 or Aquamet 17, is a common boat shafting material it is normally used used on very active vessels, it doesn't like stagnant conditions. For intermittent operation in salt water Aqualoy 22 or Aquamet 22 is a far better choice.
If you use boat shafting it is ready to go, already finished and straightened.

Aqualoy 22 or Aqualoy 22 High Strength

Click on the shafting data brochure.

http://www.aqualoy.com/

Aquamet 22 or Aquamet 22 or Aquamet 22 High Strength

http://www.aquamet.com/aquamet22.nxg