Galling between 4140 and CR380X SAE J2340??

[dtwo]

I have an application where a round pin, made of heat treated 4140, is used to locate a stamped sheet metal part made of CR 380X (SAE J2340). The hole in the sheet metal is round and flanged. The sheet metal is also hot dipped galvanized. It appears that I have "galling" between the two materials which ultimately causes a seizure between the moving pin and guide bushing (parts of the pin clamp assembly).

See photo of magnified area of surface defect showing a buildup of material that is welded to the surface of the pin.

Is this considered galling? And if so how can I prevent this from happening? How can this happen with two dissimilar materials?

 

[TVP]

Yes, this appears to be galling. The hot-dip galvanized (zinc) coating on the steel is likely the biggest contributor to the problem. You need to use some type of lubricant (oil, dry-film polymer, etc.) if you want to reduce or prevent this condition.