Heat Treatment of Steel

Relate annealing, hardening, and tempering to crystal structure and metallic bonding.
This video is part of the Flinn Scientific Best Practices for Teaching Chemistry Video Series, a collection of over 125 hours of free professional development training for chemistry teachers - elearning.flinnsci.com
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[@MrJordantalbot]

I don't understand why all the negative comments about his comment of the jet fuel, using 2 pliers, the ceramic knife, etc. Does he need to speak like an attorney to keep people from talking smack? Good video for basic understanding of heat on steel. Try not to overanalize the outside stuff, guys. What he said about heating and cooling steel is true. Enough said.

[@andregross7420]

This is the most I've ever learned from a science class. Off to college!

[@shawnholton5182]

Wow! What a great demo. I'm a beginning hobby blacksmith and this helped me understand what I'm doing when I'm hardening and tempering spring steel. Thanks.

[@bigfootandbananaman4746]

Just remember to not heat it to blue when u r tempering or the blade will become too soft. Make sure it turns light tan to retain more hardness

[@anandhakannan5875]

I tried this @ my home and it worked. Kudos to you

[@molnez]

This video is mostly wrong. the carbon in the metal is not contributing to ductility but brittleness. When the iron is being quenched, the austenite or gamma-iron turns to martensite which can hold MORE carbon. The BCT crystal structure of martensite and the high number of interstitial carbon atoms makes this metastable structure very hard. It has nothing to do with precipitating out iron carbide (cementite). The dirt left in the cup most likely comes from surface impurities from burning the steel.

[@neodine]

You are right, I cringed when he told that the carbon precipitated out from the bobby pin. B.Sc in materials science, and continuing to M.Sc.

[@rrangana11]

+molnez ... I am sorry for those students listening to his teaching or lecture...

[@robgooch6367]

exactly. it is just scaling..did you notice how he took it well past critical to form austenite (it almost turned white) scale residue for sure. How much carbon you think is in those pins? I am guessing they are "high" carbon steel which is probably .05% or so for the application...anyway I digress..but Molnez you are 100% correct.

[@shooteroffuture]

Thank god! I thought I’m going crazy while watching the vid, going through my material science memories

[@rondoschiavoni8840]

Liked your video, I want to make a torsion spring out of a wire coat hanger for my model airplane landing gear , is the wire coat hanger the right type of steel to make my landing gear with ?

[@ph1gm3nt]

I watched how ceramic knives were made and they do have some metal imbedded into it purely to trigger metal detectors. But not for structural purposes.

[@vihreelinja4743]

Not if made in china xD

[@tengkusulaiman]

When I left school last time (long time ago) periodic table were not so many elements. Now I read my kids science book in 2022, the elements got more and many more to be discovered. Im getting old, time flies..

[@Mech.Masters]

The first process is called Annealing , second process is hardening and third is the tempering......

[@danielbuttons5535]

Mech E did quenching produce martensite ?

[@bagusd.erlangga6899]

yes absolutely. another case bainite can happen too.

[@jeffsandling5981]

Great video. I'm an hvac tech at one of the world's largest steel manufacturer's trying to learn more about metallurgy. It doesn't pertain to my job so it's time consuming to get info there. My question is, is would the last example be what you'd call normalizing?

[@aaronahnes3532]

Good video, tried doing this experiment and was interesting

[@wullgrew1]

The quenching medium is the second most important part to the heat treatment. Different steel require different quenchants. For instance, O1 requires a slower medium than W2. Hypereutectoid steels mandate a faster quench to properly enclose the carbon inside the matrix. Quench 1095 in water, and quench it in Parks 50. Parks is slightly slower than water and is much easier on the steel. Water will create more stresses and can make the steel fracture. A friend has actually had edges blow off knives before. The quenchant has to be matched to the steel.

[@hphp5889]

Is there any way to apply liquid liquid to iron that iron bars can be brittle and can be like a wood stick ...? Thanks very meaningful video.

[@Conquer332]

a basic info that helps a lot.........basically a good video

[@lpblewis]

I don't think it only becomes brittle because it lost a bit of carbon when he quench it, but also because the quench causes internal stress in the structure just like in a Prince Rupert's drop. And the tempering gives it back elasticity not only from that blue coating as he says but also because it releaves some of that stress.

[@PineTopTeesVideos]

I am in the process of making hardened steel dies for coining. I will be using cold roll steel and a cnc machine to cut out/ingrave my design. Once that is done I then need to harden the steel so that it is harder then the copper or aluminum that I will be stamping. How would you propose I do that. I heard peanut oil is a good way to cool it down,

[@haroldwestrich3312]

Nice lab suggestion. Thank you I guess you just misspoke, but for others watching - the ceramic knives are solid ceramic - it is not just a coating. They will shatter like glass if you drop them on something hard like ....... Ceramic tile or a concrete floor, or glass things.

[@MisterRorschach90]

+Harold Westrich that is only one type of knife.. he did not misspeak. most kitchen knifes are indeed hardened steel.

[@shonaoneill5151]

@@MisterRorschach90 No, he said the knife in his hand was ceramic coated, it's not, he did mis-speak. Just like you did.

[@opie7afe]

@don collier why not use tool steel? im working on a hammer/trigger for a pistol and after i annealed it it was not much harder then mild, harden it up and its so hard it rips teeth off of a hacksaw. be a better option, not hard to anneal the steel.and it will last longer, cold rolled is not the best for dies

[@randyc5650]

Why must you heat it with two pliers? One should suffice unless you want to bent it open or closed while hot after you heated it.

[@rrangana11]

Randy C Exactly... I am also thinking the same.....one could use one pliers to hold and heat and quench

[@MisterRorschach90]

+Randy C exactly what i was thinking

[@FLIGHTCOMPANY]

+Randy C Probably to show it's bendy and brittle properties. Too hot to touch.

[@herenow2895]

I was thnking the same and came to the conclusion that he's a bit of a knob.

[@sanjeen2503]

Getting it so hot will make the hotter part weak. The other side not clamped by any pliers will limp and perhaps break off

[@davekgill]

Good lab yes, and a gripping speaker...

[@dova5795]

thank you, it helped me in 2017

[@killerbouquet3220]

I love this guys example and information, however, he opened a GIANT can of worms with that steel beams comment XD

[@priyadarsini9639]

John Mariscal i think he did that on purpose

[@81mrmusicman]

Absolutely, I thought he was going to elaborate a bit on the steel properties vs Jet fuel/heat/temp etc.

[@jackfennessy6677]

where can I buy the knife

[@laurensbijkerk4385]

Thank you!

[@rejimathew9863]

Excellent

[@izayasabong5205]

Thank you so much

[@christopherpaul2544]

Thank you sir.

[@danielbuttons5535]

Can you heat treat steel which has very low carbon content? Let’s say ferrite ?

[@S-TeC84]

between the goggles,shirt and hamburger housing complex on his legs he knows what he's talking about lol

[@sea-rv2bl]

i am replying after 7 years are u alive ? :D

[@vtec230]

Molly steel. ?i love his pause waiting for viewer to answer :-)

[@johnywhy4679]

If the knife if coated in ceramic, what's under the ceramic?

[@James-dg6xe]

Its ceramic all the way down.

[@hosamh]

what are the age of your students? i have trying to find a easy explenation on how the process works, i make knives for hobby you see. thank you for the lesson :)

[@sylasoce6376]

why do you need two pliers? and leaning over the bunsen burner to turn it off isnt very safe

[@FiltyIncognito]

That bit about iron carbide is wrong. He should be talking about the different crystalline structures, phase diagrams, grain size, stress/strain, elastic and plastic deformation, material failure etc....These topics can be covered without going too in depth, and they all have real-world demonstrable phenomena that'll keep kids interested. It's also what they'll end up working on post-secondary as material science and mechanical engineering majors.

[@kdmq]

7:37 He has lost his temper! pun intended

[@matenaka146]

why hold it with two pliers each time?

[@venkatchaitu1671]

when material is heated and allow it fr cooling in air means it is called normalising...... sir,but u said this is annealing....

[@tzq33tdq]

annealing is the correct term in this situation as it is a method of changing the structure of the materials

[@antoniovalencia2984]

He has a bug on his shirt lol

[@spanishforjames]

Why in the world does he need two pliers to hold a bobby pin?!?! Does he roast marshmallows with two forks?

[@sethcarson5212]

Great video. Just what I was looking for. anyone else have a brief moment of panic thinking this was about to turn into a 9\11 denial conspiracy video?

[@lromeroyt]

thank you for your video!

[@HarryKhan007]

This is the education you get at high school or college. It explains why at university, the material science professors are telling you to forget anything you learned about steel, before.

[@michaelecastillo1]

why's that?

[@squidystings]

someone who memorized some facts but does NOT comprehend what he's supposed to be TEACHING!

[@lewiswereb8994]

Don C.....the quenching medium (water, oil,etc) is not important. Only the TEMPERATURE of the medium is critical. An excellent book for this information for the average guy is "Step by Step Knifemaking" by David Boye.. No need to go thru US Steel's five ton volume of books called "The Making, Treating and Shaping of Steel".Dave Boye already did that. Peanut oil is good because it smells a lot better than old crank case oil when you swirl red hot steel in it.Olive oil would be just as good. So would clean transmission fluid, Mobil 1, 30 weight crankcase oil, etc etc.....Only the temperature matters. The cooler the oil the quicker it cools the steel. Quicker it cools, the more brittle it gets.

[@Sandarpan]

You right when you say "The quicker it cools, the more brittle it gets." But oil quenched or water quenched does matter. Water has more specific heat capacity. So when steel at say x Celsius is plunged into oil or water at y Celsius. The driving force for heat transfer is (x-y), the temperature difference. But with water when it draws heat from the steel, it doesn't heat itself up quite as much as oil would at the same temperature. So water can maintain the temperature difference for longer and subsequently cools the steel faster.

[@lewiswereb8994]

Unless you quench in boiling water......

[@Sandarpan]

Lewis Wereb Yes. But I was referring to when both oil and water are at the same temperature.

[@lewiswereb8994]

Yes, I know, but the point of my comment was that the temperature of the quench medium is the most important.....Very cold oil and very hot water versus very cold water and very hot oil will result in very different hardnesses in the same chemistry of steel.So, one has to use the temperatures they get the best results with. I use SAE 1095 steel, heated to 1450 F and water quenched in about 75 degree water.Makes a dandy little folding knife, as long as the blade and spring are annealed properly, which is a whole other subject....Thanks for tuning in on my comments.

[@robgooch6367]

temp of the quench medium in relation to the thermal properties of said medium. (vapor barrier formation etc..) that is...

[@danthemanzizle]

WHY IS HE ALWAYS USING 2 SETS OF PLIERS? IT WEIGHTS HALF A GRAM!

[@johannsangalang2193]

bcos if he does'nt hold the other side the clip will be broken ,, because it is almost melted,.. sorry for my english :)

[@danthemanzizle]

Jc Carpio nope, it's not hot enough, and the stress on it from gravity would be small compared to the stress from this guy's two arms not being perfectly stable.

[@jamessowin2505]

Agreed, it's making me crazy.

[@rrangana11]

+James Sowin Me too....

[@thelonelykloud7435]

+danthemanzizle Because bobby pins are just SOOOO frigging heavy ya know

[@RoyAndrews82]

Blue Tempered Spring Steel.

[@farmerx165]

1:12 i agree, some people say.,...,..

[@E_Flow_Ma]

Here from Koskinen’s class

[@FiltyIncognito]

But messing around with bobby pins like that won't be really interesting for them. Give the heat treatment labs a reason why they should do it well. Make it a competition. Have different categories they can win in. Best load bear. Best elastic strain. Best compressive stress bear. Most elaborate methodology. Best lab report. Winners get a pizza, or candy, or get to make the choice from a selection of future labs. To them, this is just burning bobby pins.

[@iamsad1985]

just why two pliers? just why

[@kaieteurcanada]

I dont get this... you wear eye protection where I dont see its really needed but you dont protect your shirt from catching afire when leaning over the flame to turn the burner off,.

[@archangel20031]

Just hold it with one pair of pliers for the test!

[@HarryKhan007]

He should have added a cup of oil, to explain bluing.

[@oliverpete6584]

The way this guy holding and heating the steel with two plier bothers me so much..

[@mikedelam]

You can harden cold rolled 1095 with super quench. Look for the day formula on line. Oh, this guys underlying facts are incorrect.

[@MisterRorschach90]

why is it so typical of science teachers to do things harder than they need to be? two pliers? really?

[@rrangana11]

+jordan secrist ... Since Most of them just know the theory from book and no hands on.

[@rk7567]

+jordan secrist "those that can not do teach"

[@anthonybeers]

+tyler t I'm a mechanical engineer, I blacksmith, weld, and heat treat tools in my personal shop and lay stone. At work I am constantly building prototypes for clients. One would have to be a pretty boring engineer to just sit in a cube. This is only very roughly correct by the way I doubt the pin was annealed (it is thin and cooled relatively quickly in air), it was probably normalized which relieves internal strain. If you want to learn about this get the equilibrium phase diagram and the non-equilibrium phase diagram for the particular steel you are using. Then you can know what structure you have and what properties you can expect. Based on process. Still way better than just reading the book and not experimenting. I think more experimental learning in schools that can be useful at home in some why it the correct direction.

[@sengerandu]

+Randy Kirk Perhaps that is a myopic vision

[@nicko9404]

+Anthony Beers

[@BladeAddict8]

good thing you used 2 pliers. Could have gone wrong quick!

[@rongrite]

Very good demonstration, but there needs to be a follow up, on bisphenol-A, that has been added to plastics, and laminates, and even food containers, and cosmetics, since the 1950's and has known effects on mammals, at parts in the trillion.

[@davyzeng6232]

You are exposed to more BPA in one day living normally than from doing this experiment a few times.

[@prototype9000]

Didnt really need to use 2 pliers

[@S-TeC84]

Ma eyes da goggles do nothing!!!!!!!!

[@pangpengmaster]

it does protection. danger may come anytime.

[@S-TeC84]

pangpengmaster it does protection???? Wow lol Homer Simpson spits in your food bro haha

[@telefunkenyou47]

Wealthiest country + good teachers = public schools. It just doesn't add up.

[@Clete88]

This guy's credibility really dropped anchor with me when he gives credence to the twin tower/jet fuel theory.

[@DavidBentley23]

It's not a theory

[@grryan1]

best recognize, sucka

[@michaelsloanedog]

jet fuel cant melt steel beams

[@EMR11353]

Jet fuel on fire can reach temperatures hot enough to soften steel and weaken the integrity of the structure

[@notwrkn2mch]

+EMR11353 Add to it the height at which it happened and all the wind/oxygen blowing on it you now habe a Forge which will get much hotter.... In that case jet fuel can melt steel

[@ianlombardo9758]

+Joe Z exactly my point, there were no explosives used that day at all, only accelerants, fire and high winds.

[@mrdojob]

+michaelsloanedog I work with structural steel all day and can assure you it'll get fucked up if it gets hit by a 500mph plane and set on fire for 45 mins. Really structural steel and the steel you're thinking of is totally different. Structural steel is much more malleable and flexible because it don't crack as easily, easier to work with and flexes when it needs to like wind. The properties that make it great for buildings also makes it terrible for coping with fire or high speed impact. Seeing its already flexible and very soft it neither resists fire or impact well.

[@lanceroark6386]

Jet fuel that burns off in seconds and leaves a starving fire that burns way too cool to melt steel absolutely can melt steel; just ask our government. Even the steel 40 floors below the supposed crash site melted cause heat moves down. Oh wait.

[@AniShh89]

just come into the point will ya..we are not kids!!

[@shonaoneill5151]

Really? Your grammar reveals another story!

[@erik7272]

Longest advertisement ever....

[@sreenivaskamath2341]

waste of time and data

[@Nambat5]

Jet fuel can't melt steel beams

[@OctoBrushy]

But it can make them weaker.

[@shonaoneill5151]

Wow....still flogging that old horse? Jet fuel was the fuel for the fire. The fire was well over 2000°c in some parts, guess what. Steel weakens, melts, bends at temperature such as this. You obviously didn't do to well at school.....poor boy.

[@joshskoflic8391]

Painful to watch. Get someone who looks what their doing.

[@TheDave570]

Burning jet fuel, being a lite oil, cannot burn hot enough to melt steel ??? Nor will it turn the steel to dust. He needs to go back and look at the videos of the fall of the building. It did NOT melt it turned to dust from the top down !!!!

[@joseeduardospinelli8501]

Thank you!