Punching a Hole Through Solid Steel Frozen With Liquid Nitrogen By The Action Lab

The Action Lab: In this video, I check if it is possible to punch through a steel wall if it is frozen with liquid nitrogen. I talk about the science behind freezing metals and test what happens to different metals at liquid nitrogen temperatures. - The Action Lab

hey everyone today I'm going to be seeing if I freeze a solid steel plate with liquid nitrogen can I actually punch a hole through it so we've all seen movies before where somebody freezes a safe or a gel cell or something with liquid nitrogen or something really cold and they can usually break the bars or punch a hole through the metal wall well I wanted to test if that's really the case and then I'll be talking about what cold temperatures actually does to steel does it actually make it weaker or stronger okay so I have some liquid nitrogen here first

let's test what happens when I hit an iron screw with this so this is some iron alloy screw with a zinc coating on it so first to test this I'm going to take two screws I'm going to hit one that's at room temperature and one that's a liquid nitrogen temperature and see if there's a difference in the brittleness so let's put our screw in the liquid nitrogen okay first let's hit this one i just broke my cement but not the screw now let's grab the liquid nitrogen screw hit it the head popped off somewhere so that easily broke okay so you could easily see there was a difference between the two screws the one that was at room temperature and the one that was at liquid nitrogen temperature were definitely different i could easily break the colder one but let's take it a step further and see what if i freeze an entire steel plate

so you can see this has already been through a lot let's see if I can actually break through it with liquid nitrogen and the way we're going to see when this gets to liquid nitrogen temperatures is when we no longer see the lead in frost effect now the lead in frost effect is when we see little beads of liquid nitrogen rolling on top of it that's because compared to the liquid nitrogen the steel is so hot that it creates this pocket of gas below it but as soon as the temperatures get closer together then it's going to spread out on top of the steel so you can see in the middle here how it's not rolling around in these little spheres on the side see on the outside here it rolls around and bubbles but here it's sticking to it so once it starts sticking to it you know it's a liquid nitrogen temperature right in the centre so this is right where I'm going to punch it

okay here we go got it okay one-two nope not getting through that ow okay I should really have goggles on if you have a hammer yeah i'll do this part even with the hammer doesn't work anything, okay so that did not work I wasn't able to get through the steel with my fist or a hammer and the same thing when I cool down some rebar to liquid nitrogen temperatures and strike it with a hammer i can't get it to really shatter now normally it seems natural to think of things breaking when we get them really cold because we've seen videos of whenever you freeze things like for example freezing this flower here and then hit it against a table it just shatters into a million pieces but the reason things like this shatter is because they have water in them and the water forms ice inside and then the ice can easily break but that same logic doesn't hold true for why does a metal break easier when you freeze it

well the first thing you have to understand is that when you cool steel down it doesn't actually make it weaker but it actually makes it stronger

so despite what your intuition might tell you even in the experiment where I hit the screw and it broke that screw wasn't actually weaker it was actually stronger than the one at room temperature now the thing that keeps the material strength is the ability to be slightly ductile meaning it can bend a little bit for example if I make a graph of the yield strength of 410 stainless steel you can see that as i start at 50 degrees celsius the yield strength is only down here but as I decrease the temperature to negative 200 degrees celsius the yield strength rises to here and

so as i decrease the temperature the yield strength increases but the thing is when you have something that yields at a higher strength it usually means that it's more brittle so instead of yielding it just breaks so instead of bending it just breaks in a fracture so really high strength or hard things usually are pretty brittle for example if i just take a diamond here's a real diamond and hit it with a hammer it fractures into a bunch of pieces so the diamond is very hard but it's also brittle the same thing happens with glass

glass is actually very strong and very hard but it fractures really easily so when you lower the strength of the still you're actually decreasing the toughness of it even though you're increasing the strength. now the brittleness of the steel is completely dependent on the type of steel it depends on the alloy itself and it also depends on how that alloy was treated for example there's a test you can do that measures the hardness and you can measure its impact strength and if you take three different sheets of steel here's how the impact strength would look at different temperatures so you can see for some steels as you decrease the temperature it just drops down at some specific temperature and this transition here from high impact strength to low impact strength is called the ductile to brittle transition and you can see that for some low strength steels there's an abrupt transition but then for other low strength steels like this brown line where it's not as abrupt but for some high strength steels

it's lower the impact strength is lower and then also there's not as an abrupt transition either so it completely depends on your steel alloy and it depends on your type of metal all together whether you're using steel or not in general if your metal is pretty ductile at room temperature it will probably still be a little ductile even at liquid nitrogen temperatures so that's why when i tried to break this aluminium bowl that was a liquid nitrogen temperature it just bent didn't break or even this aluminium beam try aluminium doesn't break okay here's the frozen gallium frozen with liquid nitrogen let's see how brittle it is whoa so can liquid nitrogen be used to make metals more brittle well yes and no

it depends on the specific type of metal that you're trying to break if it's something that's already ductile it probably won't work very well if it's a very specific type of steel alloy you could break it and thanks for watching another episode of the action lab i hope you enjoyed it if you did don't forget to subscribe to the channel if you haven't yet and also hit the bell so that you can be notified when i release my latest video and thanks for watching and i'll see you next time