Hej folks,
:topic:
due to some warranties, I was asked to review a P-FMEA on a hot dip galvanizers site. However I must confess, there is no much knowledge about deep details of HDG in in our company. There is mentioned a section "liquid metal embrittlement" :confused: - does anybody here has some experience with this (obviously rare) occurance?

Thanks for your help in advance!
:thanx:
With best regards
MaWin

embrittlement (also see "hydrogen embritlement") is not rare - it is a frequent cause of failure in a lot of platng situations. With hot dip zinc (definitely NOT my area of expertise), I have heard one of the proximate causes is the temperature of the cooling process after the dip.

I might suggest you check with some other websites specializing in metal fnishing troubleshooting.
FWIW, try looking over these industry association links for company names (chemical suppliers for all plating and finishing chemicals often have troubleshooting Q/A pages or a "go to" guy to answer such questions):
http://www.namf.org/
http://www.finishing.com/
http://www.aesf.org/
http://www.mfsa.org/
http://www.nmfrc.org/

Hej folks,
:topic:
due to some warranties, I was asked to review a P-FMEA on a hot dip galvanizers site. However I must confess, there is no much knowledge about deep details of HDG in in our company. There is mentioned a section "liquid metal embrittlement" :confused: - does anybody here has some experience with this (obviously rare) occurance?

Thanks for your help in advance!
:thanx:
With best regards
MaWin
In a molten lead (approx 1400-1800 F) wire patenting quench we woudl erode the steel lead pots , the molten lead acting as a corrosive tohte steel pot and also the temperature cycling would exacerbate this problem by continually cycling the stresses in the pots themselves ( think of a 30 foot long , 2foot deep , 6 foot wide bathtub affair) which would lead to fatigue cracking. If this is process failure mode you are reviewing perhaps HDG may have simalar failure modes. If the is product fmea they may be referring to instrusion of the zinc into the substrate causing essentially dislocation pinning due to intrusion into and upset of the crystal matrix.. result=embrittlement. Hydrogen embrittlement in steel heat treating is probably similar. You heat up a metal' scrystal matrix and all sortsof ugly little things can slip in and foul up the works. I am Mech Engineer and was QM in steel wire mfg for 12 years and know enough metallurgy to get me in a lot of trouble. You could call a local metals test lab and ,for free , get bored out of your skull by a metallurgist with some time to kill that would love to tell you all about it. Just play dumb and you will get all you could ever want to know. Metallurgists don' tget out much.

Hydrogen Embrittlement - yes many years ago, I was the Quality Manager of a company that produced tractor trailers. We did get into a situation where the wooden floors that were held on with zinc plated screws had the screw heads pop off. We didn't know what why this was happening.

We found out that it was caused by hydrogen embrittlement caused by not baking the plated screws after plating.

The easy to confirm this situation was to take a sample at receiving, place each in a vise and tap the sides of the heads. If the product had embrittlement, the screws were like glass and the head would pop off. Baked product would just bend.

Now, does your company own the process of galvanized dipping? I don't think so and I would suggest that you supplier's Process FMEA should be reviewed. Place the responsibility on your supplier and only they can make changes to their process.