Stainless Steel galling

[cpina]

I was wondering what are some of the current methodes used to prevent stainless steel from galling, other than lubercation? Also does anyone know what is really happening when the two objects gall together?
PS. More specifically I am referring to SS316

 

[IndianaEd]

What is the application? There are material types like gall tough that prevent this depending upon design and application.

 

[NickE]

Galling is welding of the two components on a very small scale. This welding occurs because the oxide film on these materials is thin and weak and is broken completely causing two virgin surfaces into intimate contact.

Using two different materials can help. IE 316 vs hard chrome plating. Also fasteners are commonly plated with silver. (or at least thats what they tell me.)

There are alloys developed to resist galling while still having decent properties. IndianaEd mentions GallTough, htere are others.

 

[cpina]

I'm on a NASA coop right now and they have me working on a project assosiated with galling. However I couldn't find much info on galling so I was hoping that I could get afew key words from asking the question that I could use in search engines. I understand tha it is caused by something similar to friction stir welding, but I was, and the application is basically trying to find another method other than lubercation
Thank you for your help

 

[jnims]

I have looked at this issue some and asked a similar question in one of the other forums. Some possible mitigation methods other than lubricants are:

Galling resistant Stainless Steels are available.
Use of a torque wrench to prevent over-tightening.
Silver plating.
One manufacturer suggests Silicon Bronze nuts.
Rolled threads – hardware surface is smoother than machined threads.

 

[Danimal001]

I have found that burr's and poor surface finish aids in galling. We use alot of 300 series sst npt threaded fittings and whenever we run them over a general buffing wheel we never have problems. Impractical for high volume manufacturing, but maybe this will help. We have also seen this when we screw 300 series sst fittings into HP die cast ports. Poor thread construction has an impact.