Galvanizing high strength steel bars and rods

[71corvette]

How can one determine whether high strength steel bars and rods can be galvanized without significantly altering the mechanical properties of the steel? Specifically, I'm talking about materials typically used in the prestressing industry with very high tensile strengths (i.e. ASTM A722 bars, Ft=150ksi). I realize that galvanizing is especially difficult when working with quenched and tempered steel, but what about steel that isn’t quenched and tempered? Are there specific guidelines or rules-of-thumb that should be followed when contemplating galvanization for these materials?

Thanks,
Tim

 

[Lion06]

what kind of altering of mechanical properties can HDG do to any bar? I didn't think HDG changed anything. Is there a different type of galvanizing that you are talking about or maybe I am just in the dark. Either way, I am curious.

 

[lkjh345]

tinytim22:

I would definately discuss this with a galvanizer. I think, somewhere, AISC says that A325 and A449 material can be hot dipped galvanized, but that A490 material cannot be. I hope I am not mistaken on that. I am not sure about A722.

I might be possible to mechanically galvanize this material istead of hot-dip galvanizing.

Consult with a galvanizer is unsure.

 

[PEinc]

I always thought it unwise to galvanize Grade 150 bars. However, Williams Form Engineering's Ground Anchor Systems Manual, No. 103, page 33, says "150 KSI high strength steel bars should always be mechanically cleaned (never acid washed) to avoid problems associated with hydrogen embrittlement." I would check with more than one bar supplier such as DSI, Williams, or SAS.

 

[csd72]

There are a number of potential issues with galvanising certain high strength steels.

A good place to start your investigation is:

http://www.galvanizeit.org/

csd

 

[JStephen]

I ran across this a couple of days ago- I haven't read it, so don't know that it addresses your concerns:

ASTM A143/A143M-03
Standard Practice for Safeguarding Against Embrittlement of Hot-Dip Galvanized Structural Steel Products and Procedure for Detecting Embrittlement

 

[WillisV]

csd72 pointed you to a good resource - for a specific article concerning the possibilities of embrittlement for high strength steel see:

http://www.galvanizeit.org/resource...lv/Embrittlement/diff_forms_embrittlement.pdf

Essentially if you have Fy equal to 150ksi or above (as you do), then galvanizing is not a good option due to hydrogen embrittlement.

Also see Q/A No. 10 on AISC's site:

http://www.aisc.org/MSCTemplate.cfm...Management/ContentDisplay.cfm&ContentID=32229