Bob JS

Hydrogen Embrittlement Concerns

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I was hoping that I could use the electrolysis method to clean the hammers that follwed me home last week, but I have questions about Hyrogen embrittlement:

Is it a concern with hammers? - or just small items like springs etc

I understand the hydrogen will be released from the steel over time - but I cant find any info on time scale - how long does it take? day months, years??

I also understand that baking the piece in an oven bellow tempering temperature will drive out the hydrogen - is there any safety issues here? I imagine the volume of hydrogen relased is small, but I like to be sure when dealing with hot explosive gasses in the house!

Thanks for your help, advice and opinions.
Bob

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I can't spead to your Hydorgen concerns but if those hammers where in my possesion I would just let them soak in vinegar a day or so...my.00002 worth...;)

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The hydrogen can indeed be baked out at about 250F for an hour. The volume of gas released is miniscule. However, I doubt even this is necessary for hammers. The hydrogen can evolve out of the metal in a few weeks at room temperature, faster if you just leave them in the sun.

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Is this really a concern? I've never heard of it. How does it occur? What causes it?

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Stressed metals like springs develop micro cracks that hydrogen molecules can work into.

When that happens the metals harden and loose their elastisity, become brittle and break under stress. The industrial gas company, that I worked for, was shipped a lot of hydrogen cylinder valves with springs in them that became brittle. Over a period of time we had to remove and replace every valve from that lot. A real pain in the budget.

Edited by Charlotte
insert left out word

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Except in Charlotte's case (high pressure) hydrogen does not become entrained in steel at room temperature. It is why they make low-hydrogen welding rod, but sometimes that's not even enough. Saw a job once where the steel they were using had a high susceptibility to entraining hydrogen. All the test coupons were breaking. Old salty welding engineer said leave all the rest until tomorrow. Next day most passed. Determined to be hydrogen embitterment and just leaving them over night was enough.

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Thanks for the info and advice.


Dodge, It can be caused by electrolysis - which produces hydrogen gas. Apparently this can be absorbed into the lattice of the steel, and prevents the molecules being able to move/slide around if impacted or bent - embrittlement.

I wont go into too much detail, because I only 'know' what I have spent the last few days reading - but there is usually a very vauge cautionary note at the bottom of the sets of instructions for electroysis found on the net.

Apparently it is common for parts to be baked in ovens after electroplating in industry.

Thanks again.
Bob

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Thanks Bob. I also did some googling and read about the electroplating aspect as well as the hydrogen gas produced. It makes sense now. Since most of my experience is with mild steel, I just had never heard of it. Apparently, not as big a threat with mild.

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Hydrogen embrittlement was a problem encountered in parachute hardware, many decades ago. The snaps and D-rings were forged, polished and then plated for rust resistance. The parts were failing under load test. The problem was eliminated by post plating baking, to drive off the hydrogen.

Another place hydrogen causes problems is in the oil field, where "Sour Gas" a slang for Hydrogen sulfide is present in the natural gas and crude. This H2S will embrittle hard steel. The standard for valves and piping in this service was written by NACE, and requires no steel harder than Rockwell 22B. That makes it hard to find a hard ball for ball-check valves, as well as hard materials for seats and gates. There was an Inconel material for springs as I recall, but very expensive.
We loved making these NACE valves as there were big$ and did not last long, so good repeat market:)

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