Is there a danger of embrittlement of hardened steel parts using electrolysis for rust removal? I'm thinking leaf springs, axles, etc. Don't want to destroy parts, just clean them. Thanks.
Cant directly answer that question but dont leave aluminum in there very long at all.Or dont put it in there unless you are close and can remove in a few minutes..
I did some with sucsess because I just left it in the tub for a few minutes to loosen up tough crap.
But I left a aluminum oil pan for a Briggs Model 8 in there to long and it started to damage the thin areas of the gasket surface.
I'm no chemist, but I have done some reading on the subject, and it seems mild-steel is safe but hardened, cast, or spring steel parts might suffer from hydrogen embrittlement, depending on the alloy.
A friend of mine did it to the window regulators on his Chevelle, and the springs started breaking after a couple up & down cycles. Those were much thinner pieces, but I wouldn't try it on any critical structural components.
I have used the electrolysis rust removal on crosscut saws for many years and have never noticed any hardening or embrittlement issues. The saws are essentially the same as spring steel. It usually takes a few hours with DC welder power but maybe with a much longer time, there could be a problem.
I've been using electrolysis for rust removal for over a year but only on sheet metal and non-structural components with no issues.
I would be concerned if you were electroplating the parts, but you are doing the opposite which should have little or no effect on hydrogen content of the part being de - rusted.
Wish we could edit posts here... oh well. I was wrong about the window regulator springs mentioned above, he used acid not electrolysis.
What I've read about it though seems to be inconclusive with people on arguing either way on different alloys.
Hydrogen embrittlement isn't an assured thing when using something electrolysis with hydrogen being freed up as part of the process, it just comes and goes sometimes in a process and you never know when it will bite you.
As others have said, hardened steels tend to fall into that 'gotcha' and if plated the plating will/may also blister from within if there is hydrogen embrittlement beneath.
Quick answer? On mild steel you have the odds of almost a lottery ticket of getting 'caught' with a surprise. Part not too big? Borrow the missus oven and cook it at 375-400 for about 4 hours and that luck of the draw on embrittlement goes to zero on all steels even hardened ones. A problem does occur if you bath it too long at too much current. Its not hydrogen embrittlement that is the result of that extended bath...iron grains literally disappear and head to the other pole and leave the surface etched with tons of sharp little corners that become stress risers in bending fatigue. there is a magic number for amps/sq.in. in reverse electrolysis versus time to keep too much etching at bay...but right now I don't remember where to look and quite frankly I tend to think that a battery charger is too little amps for any reasonable size to get the etching problem.
Thanks for all the responses. I plan to set-up a small bath for small - medium size parts that will fit in a 20 gallon keg tub. Larger stuff (spring leaves, axles, wire wheels, etc.) will need to be blasted.
See this post: