×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Zinc and 300 series combination

Zinc and 300 series combination

Zinc and 300 series combination

(OP)
Hi all,

I'm not a corrosion engineer, so forgive me if the terminology I use is incorrect. I have a 304 stainless steel stud bar passing through a hole in a galvanised carbon steel plate. I have been advised that to mix 304 ss and galvanised materials is not recommended as the zinc interacts with the chrome in the stainless steel, reducing the strength of the stainless steel. The application is in an air cooled heat exchanger, holding the motor adjusting plate to the bridge frame, the temperature probably will not exceed 40 deg celsius. The top stud bar is under tensile loading and the bottom ones under compressive loading, due to the vertival mounting arrangement.  Please supply any advice.  Thanks.

RE: Zinc and 300 series combination

What is the rest of the environment (chemicals, cyclic exposure to water, etc.)?  In general, the more active metals (the zinc and carbon steel) will be corroded vs. the more passive metal (stainless steel).

RE: Zinc and 300 series combination

As long as you don't weld the only problem that you will see is somewhat accelerated corrosion of hte galvanized steel parts.

= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection
http://www.trent-tube.com/contact/Tech_Assist.cfm

RE: Zinc and 300 series combination

Zinc embrittlement of austenitic stainless steels occurs slowly at 419-570 oC, and more rapidly at higher temperatures, becoming extremely fast with crack propagation above 750 oC. From

ASM Handbook Vol. 13A, Corrosion: Fundamental, Testing, and Protection p. 390-391 (2003).

Welding and fires can cause catastrophes. SS is preferably passivated after any contact with zinc.

RE: Zinc and 300 series combination

Ionic Zinc reacts with ionic chromium (in its hexavalent state) in an acidic catalyzed solution to form zinc chromate. I would not think this reaction should occur in their uncharged state as metal. The only reaction I would expect is the zinc corroding, which is why zinc is sometimes referred to as a sacrifical coating.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources