Brass C360 and stainless steel 301 corrosion compatability?

[bennetkd]

I was hoping someone could help me out with a design question:
One of our current design proposals is to have a CA-360 Brass Screw(size # 10-48) in contact with a Flat thin Stainless Steel 301 series spring. The screw is mounted in plastic and is in point contact with the SS. Both metals are inside a plastic assembly. Moisture is possible but not usually present. Very light operating forces(ie 75 grams) between the two metals. This is an automotive application- temperature ranges this part will see are between -40C and +125C. The warranty life of the part is 15 years. Is there an issue here with Galvanic Corrosion?
Also, would anyone see an issue with using J405 SS instead of 301 SS?
Please advise.
Thank You

 

[grayseal]

bennetkd,
A have a similar application. A 360 (half hard) brass fitting is brazed (BAg-24) to a 304 stainless steel sleeve of an autoclave. Operating temperature is 270 degrees F. These units have been in service for more than 15 years and have seen no corrosion problems. I think the alloys are similar enough to say they are the same. Brass and 18-8 stainless steel are fairly close together in the galvanic series, and coincidently, the silver brazing alloy is between them in the series.
Hope this helps.

grayseal

 

[rustbuster1]

Grayseal seems to describing conditions that are dry, so galvanic corrosion would not be possible anyway. You posted this question a while back and I'm surprised no one answered yet. Maybe the 15 year time line is a bit intimidating.

Nevertheless, there is very little likelihood of galvanic corrosion in the conditions you describe. The wetness reportedly would be very infrequent - dryness means no corrosion. And even if there was some wetness, e.g., via condensation, the driving corrosion mechanism would be oxygen reduction (unless the pH of the condensing liquid is lower than 5) and both these materials are not corroded by that mechanism.
As long as chlorides are kept away, both 405 SS and 301 SS will endure. Some automobiles operate on salted roads and near the sea, so don't overlook this.
They are called stainless because adding 12% Cr makes them unstainable (non-rusting) in "normal" atmospheric exposure but they experience crevice corrosion if chlorides are around, even if there is only oxygen reduction to drive the corrosion reaction.

Fnally, in case it matters, good electrical contact between the brass and SS will not be assured over the long term even with minor corrosion.

Good luck!!