How much is too little clearance...

Jarrod · Post by **Jarrod** » August 14, 2007, 1:34 pm

I have heard of Hydrogen enbrittlement, but I was under the impression that practices of chroming had changed over the years to limit the risk. For that reason, one should only go to a very reputable shop. I remember reading about a guy who had his Jag wire wheels chromed the splokes broke while driving. It was later learned that hydrogen enbrittlement caused it. What is the difference between decrative chroming and hard chroming? If chroming is so dangerous, then why are chrome wheels still available?

Comet · Post by **Comet** » August 14, 2007, 1:48 pm

I don't know the differences in the processes, but the chrome guy told me the chrome layer in hard chroming goes directly on the parent metal (no nickel and copper, which give chrome that bright shine). Hard chroming is used for things like hydraulic cylinders. Obviously they have ways to address the concerns because hard chroming is used in heavy industrial applications all the time.

Comet · Post by **Comet** » August 14, 2007, 1:52 pm

Garbz wrote:I was always taught not to chrome bolts due to the hydrogen enbrittlement never heard about the other things.

Garbz

Yeah, think of all the lug nuts chromed out there.

Hawkrod · Post by **Hawkrod** » August 14, 2007, 2:10 pm

Plating is not dangerous if the item is treated. Things like wheels and lug nuts are treated as soon as they are made which prevents any issue. The problem is that in electro plating hydrogen is bonded into the metal lattice. As long as the proper treatment is done it is not an issue but the problem is decorative platers do not treat after plating and the risks are enourmous. Any plater who is DOT or FAA certified will treat the parts such as wheel companies so this isn't an issue. the issue is being sure the treatment is done which usually involves baking the parts for an extended period. I did check and nickel and copper plating do share the exact same risks as chrome and your plater misled you if he said the copper kept it out. I got this directly from FAA worksheets and an FAA inspector. It is plating not the material that causes the risk. It is also not just plating, certain chemical cleaning and treating process' and hydrogen rich environments cause the same problem and may be part of the cause of the failure of the Hindenberg. Hawkrod

Garbz · Post by **Garbz** » August 14, 2007, 2:17 pm

And here i thought George C Scott brought the Hindenburg down...... :shock:

In all serious intresting info Tom.

GArbz

FORDBOYpete · Post by **FORDBOYpete** » August 14, 2007, 2:48 pm

I concur with Hawkrod, Hydrogenation, or hydrogenous adoption on a sub molecular, or atomic level is injuroius to all metals to some degree at least. Failure to correctly anneal (compensate sufficiently) for unwanted ionic hydrogan enrichment will
affect metals negatively. :shock:

I cracked a few chromoly chassis before I figured out we were doing something wrong, and what we were doing was
ignorantly plowing ahead without a clue. :hm:

Metallurgy is a real science and metallurgical engineers speak a totally different language than others. . . . :roll:

Time X Temp Ratio for Annealing Processes depends on the metals, the corruption that could have occurred, the time
metals had to become corrupted during and how many times the process occurred on each piece. :shock:

The key as Hawkrod says is Face lattice structure, pattern, & complexity of the host metals. That affects the Impact of
transitory hydrogen atoms present during electrolytic processing. :shock:

The guys I talked to made it real simple for me, If it flexes don't plate it, and if it is an exotic alloy don't weld it electrically
without knowing what needs to be done to correctly anneal it after you weld.

I'm no expert but I am familiar enough to know when I need to ask some questions of & get answers from experts. :thumright:

And I agree with Garbz here too, Great thread guys. :cheers:

FBp

Post by **Greg D** » August 14, 2007, 4:38 pm

Was a big article in Street Rodder a couple years ago concerning this. The focus was on chroming front axles, seem to remember the biggest problems came from chroming cast parts.

Hawkrod · Post by **Hawkrod** » August 14, 2007, 5:30 pm

Front axles are forged not cast and the issue is actually worse on hardened parts. Soft metal is nowhere near as much risk as it can flex with the issue but harder materials and anything that has been hardened (intentionally or even work hardening) is at risk which is why things like fans and axles are such an issue. Other parts that are risky are any springs or suspension components. You ever wonder why big rig frames have big stickers that say "do not weld or drill"? Welding also causes hydrogen embrittlement. Hawkrod

Jarrod · Post by **Jarrod** » August 14, 2007, 5:49 pm

When I first heard about this a few years back, I just figured that I wouldn't chrome anything that is structural or load bearing.