coozer
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 posted on 28/11/08 at 07:45 PM |
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Hydrogen Embrittlement
Any experts here, and I do mean experts who can tell me if the little tank I subject my rusty parts to will suffer from Hydrogen Embrittlement?
Do I need to worry about my rear drums, front uprights steering shaft etc that I did years ago and now my rusty flywheel?
Is there enough absorption to affect these cast items??
Steve
1972 V8 Jago
1980 Z750
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r1_pete
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| posted on 28/11/08 at 07:51 PM |
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This guy seems to know what he's on about.....
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coozer
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| posted on 28/11/08 at 08:39 PM |
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Thats a vague description with no results. I understand the principal but would like to know at what level it becomes dangerous to heavy cast
automotive parts.
Now, we make safety critical steering components where I work and there is a fair amount of high temperature welded joints. You can see them on your
steering shafts where the yoke is welded on. These joints are a lot more susceptible to hydrogen embrittlement in my opinion. The effects are
overcome by free to air, and sometimes fan assisted cooling, depending on the application.
I'm looking for the definitive answer to my 2 amp 4 hours soak. Yes there are bubbles but these are a combination of H and O at very low
volumes.
Steve
1972 V8 Jago
1980 Z750
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NS Dev
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| posted on 30/11/08 at 10:50 PM |
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no-one will give you a perfect answer.
The metallurgists at the steel mill where I used to work said that I would get embrittlement, but it would probably be of no significance..........
That was without prompting, I never mentioned it to them, just described the process.
They then went on to say that a stint in an oven at 180 deg C for a few hours would drive the hydrogen back out again and the problem would be
non-existent.
Its surface cracking that it causes, and it needs the surface to be under some stress, so uprights etc shoudl be fine, steering shaft and flywheel is
anybodys guess, so stick em in the oven afterwards.
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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907
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| posted on 1/12/08 at 12:42 AM |
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IMHO
Hydrogen... A welders view.
When stick welding with normal electrodes, especially damp ones, hydrogen is adsorbed into the weld.
It forms in little pockets on the grain boundaries. Immediately after welding it starts to defuse out and
continues to do so till it has gone. This takes about three weeks.
To visualize this think of an old brick wall where bits of cement have fallen out.
The test for hydrogen adsorption is to submerge the test piece in paraffin and wait for bubbles to appear
on the surface, assuming you have three weeks to spare. 
Low hydrogen rods have calcium carbonate in the flux to limit hydrogen adsorption.
MIG and TIG are low hydrogen processes.
The effect of these microscopic voids in a ductile material like mild steel is to reduce its tensile strength.
The effect in a higher carbon steel would be to make it more brittle.
I can't see that at room temperature hydrogen adsorption would be significant, after all, a steel gas cylinder
that contains hydrogen doesn't disintegrate after a period of time.
Just my thoughts on the subject.
Paul G
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