Embrittlement caused by liquid hydrogen and other materials effects of cryogenics temps

[kunok]

As I put in other thread:

"I always heard about the embrittlement of structures with the LH, but I never read something serious, can someone provide with some open info? My knowledge is principally about iron derived materials, and then "usual" car/aeronautics alloys, always in normal or high temperatures, but never in cryogenic."

We can make a more general cryogenics effects in materials thread.

[Camacha]

Good question. I remember a documentary that was filmed on the North Pole. People kept breaking their filming equipment, because the cold meant everything because so brittle the slightest force would cause it to break. Plastic, metal, you name it. Of course, those are not high grade materials, but the cold is much more benign too.

Edited March 19, 2016 by Camacha

[wizzlebippi]

As far as I know, it doesn't have as much to do with temperature as pressure. A hydrogen molecule is small enough to slip through the crystal structure of the metal tank that contains it, which is why hydrogen is so hard to contain. Occasionally, the hydrogen gets trapped in the interstitial space.  When force is applied to the crystal, the atoms that make up the crystal can realign around the hydrogen molecule, creating a defect.  Eventually, these defects can cause cracks or failure of the tank.

https://en.m.wikipedia.org/wiki/Hydrogen_embrittlement

[mikegarrison]

Hydrogen embrittlement does not require cryogenic temperatures. It is also a problem sometimes encountered in the rebar of concrete water pipes. Probably other places too.

In fact, if wikipedia is to be believed, the warmer the temperature, the more hydrogen diffuses into the metal. https://en.wikipedia.org/wiki/Hydrogen_embrittlement

Edited March 19, 2016 by mikegarrison

[Red Fang]

Any welder will confirm that not drying stick electrodes before welding is a bad idea, especially electrodes with cellulose coating. Hydrogen from electrode coating or rust buildup on the filler wire will easily penetrate deep into the weld and potentially parent metal at welding temperatures making the weld brittle. Not super important on some things, but very important on pressure vessels, or other items that may fail due to a poor weld and do damage to people and property.  

[kunok]

I was looking for damage made by liquid hydrogen that's why I didn't get anything useful searching, I didn't think it was hydrogen general effect, non a cryogenic one Now that I only look for hydrogen embrittlement I get a lot of info.

So basically the hydrogen diffuses in the structure, making interstitial defects in the crystal structure of the grains, lowering the resistance and ultimately making crack nucleation. That's not counting the cryogenics efect

1 hour ago, Red Fang said:

Hydrogen from electrode coating or rust buildup on the filler wire will easily penetrate deep into the weld and potentially parent metal at welding temperatures making the weld brittle.

I already known this, how I didn't link this to the topic (facepalm for myself).

 

Looking at the info given, a cryogenic low pressure tank (low temp and pressure makes lower diffusion), with an austenitic steel structure or some other demonstrated materials to be resistant to hydrogen brittle, shouldn't have that kind of damage, for using it in a some kind of reusable vehicle. It even looks like it's doable to do with composite lighter materials: https://en.wikipedia.org/wiki/Lockheed_Martin_X-33#Continued_research

 

[fredinno]

Can you mitigate it enough to allow its use on fast turnaround RLVs?

[PB666]

Very cold liquids are stored in double walled containers that are often supported from the opening downward, so called Dewar flask, the temperature transition is gradual around the top of the flask and most metals adapt quite well. A liquid nitrogen tank, for example one we have still holds well after 40 years of continuous use, that includes a refill cycle every week.

Double wall containers will also slow down the rate of hydrogen loss, but not at the valve.

[fredinno]

54 minutes ago, PB666 said:

Very cold liquids are stored in double walled containers that are often supported from the opening downward, so called Dewar flask, the temperature transition is gradual around the top of the flask and most metals adapt quite well. A liquid nitrogen tank, for example one we have still holds well after 40 years of continuous use, that includes a refill cycle every week.

Double wall containers will also slow down the rate of hydrogen loss, but not at the valve.

But those are heavier....