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HYDROGEN EMBRITTLEMENT ON HOT DIP-GALVANIZED COMPONENT
2007
DEAR SIR/MADAM,
WE HAVE COMPONENTS MADE OF STEEL AND WERE SHERARDIZED BUT WE WANT TO STRIP (USE HCl), AND GALVANIZE THEM TO OUR REQUIRED THICKNESS, WILL WE EXPERIENCE HYDROGEN EMBRITTLEMENT ON THESE COMPONENTS? IF SO, WHAT TESTS CAN WE DO TO VERIFY THAT?
MANY THANKS,
QUALITY CONTROL MANAGER - JOHANNESBURG, SOUTH AFRICA
You didn't say what type / grade of steel you are considering this on.
Low carbon mild steels rarely suffer from Hydrogen embrittlement in galvanizing, whereas higher carbon steels do.
Is the part a critical part in a stress situation? (lifting component etc)?
Geoff Crowley
Crithwood Ltd.
Westfield, Scotland, UK
2007
2007
Sir:
Since 1972 I have never experienced hydrogen embrittlement after hot dip galvanizing. I have in the last five years seen destroyed steel galvanized products (cracks) due to tin in the galvanizing zinc.
Regards,
Galvanizing Consultant - Hot Springs, South Dakota, USA
Dear Sir, Failures of hot dip galvanized parts may be of (at least!)three types: strain aging embrittlement, hydrogen cracking or liquid metal embrittlement (LME). In some cases two of these mechanisms occur together, resulting in extremely brittle behaviour of the parts. Whether hydrogen cracking during the pickling prior to galvanizing has played a role is often not easy to decide. The cracks eventually created by hydrogen cracking will normally be filled with Zinc during galvanizing. This makes it difficult to conclude whether the cracks are the result of hydrogen cracking or of LME. Since the fracture surfaces of the cracks must be cleaned from the Zinc prior to investigation by e.g. scanning electron microscopy, it might be possible that the features which normally make it possible to positively identify hydrogen cracks are disturbed.
astmb633.htmla143.html" --> deals with strain aging embrittlement and hydrogen cracking. LME (or LMAC=Liquid Metal Assisted Cracking) is not treated in the ASTM standard. The occurrence of LME is (presumably strongly) favoured in Zinc baths containing considerable amounts of Sn.
Jan Quist- Amsterdam, Holland
2007
Q. I want to know if really true that the 10.9 black bolt will loose the Tensile strength if you put the coating of Hot dip Galvanize and why?
Joffrey Vespiras- Dubai, UAE
March 28, 2012
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