Austempering for Bainite - Super Toughness!

Austempering is the process for forming bainite. What is this special microstructure in steel? How does it improve toughness over martensite?

00:00 Intro
00:11 Austempering and Bainite
01:29 Salt Furnaces and Salts
02:11 Why Bainite?
05:27 Hardness of Bainite
06:47 Understanding the TTT
14:56 New Experiments
18:08 52100 Results
20:14 O1 Results
23:31 1095 Results
24:55 Austemper High Alloy Steel?
27:03 When Should You Austemper?
28:27 Patreon and Knife Engineering

[WessexBladesHandMadeKnives]

I've been trying to "tell" of this for years, thanks for highlighting!

[fdr]

It is kind of insane how many variables there are in steel metallurgy. A video on marquenching+cryo next? heh...
Thank you for another awesome video!

[hificat]

Hi Larrin. I'd love to see a video about DLC coating and Rockwell hardness. I have a hard time wrapping my mind around how applying a very thin coating of something harder than the blade steel, actually reduces HRC. It's kind of counter intuitive, and I think a video on it might be very interesting.

[吳承瑾-vk]

Thank you Dr. Thomas, l am a knife maker in Taiwan and got a lot of help from your articles.

May l ask a question? I am curious about that will there be some difference in wear resistance between tempered martensite and bainite(especially for Carbon steel)? Because there will be rare or very small size carbides after carbon steel got quenched, but in bainite carbides form completely.

[Leftyotism]

Whoah super toughness!!!
I want that!

[AbbeyRoad]

Phenomenal video.... wow! Brilliant work!

[trplankowner]

Another great video Larin, thank you very much as always!

[glebtcheslavski]

An excellent discussion, thank you, Larrin! Very interesting.

[kingdarkem]

I never thought I'd pop a chub during a lecture on bainite formation in knife steels, but then again, when you start talking about tough, resilient structures under pressure, it's hard not to feel a little heat treat in the air! 😂

[JFirnQ]

Extremely interesting. I will definitely utilize this as I don't need the absurd hardness of 60+. I wonder what would happen if you did indeed austemper something like high speed steel for 48hrs lol.

[fearlyenrage]

Nice clip. There are metalrecipes with tin and bismut that go around 400°C you can long quench then the steel in a metalbath. Looks fancy too 😅

Just never drop a blade or whatsoever with oil or grease on into such a high temp liquid or it will EXPLODE into your face. Why? Because the stuff will like to evaporate in the 400°C bath.

The blades are very tuff indeed, we made some a few years ago.

[TheDuckofDoom.]

You could compare the 1095 result (24:00) to a hitachi white paper #2, or Takefu V2c (V2 has a touch more nickle and Cr), which should both have tighter control of P and S impurities than 1095.

[S.Vallieres]

Hello Larrin,

amazing video/study as usual. I'll definitely read the article too.

I most likely didn't understand everything and will need to read the article, but from this study, should I be able to understand how Howard Clark achieved bainite on the spine and martensite on the edge for its L6 sword?

[EAwert]

I have worked with C130/ C125U that is 1.3%C carbon steel, I'm sure the toughness difference at 61hrc would be huge

[thsinner]

Makes me wonder how much tougher zdp could be in tempered this way, whilst keeping the insanely high hrc.
I've never really understood bainite processing, this video helps me make some sense of it, but it also gives me the impression that my favourite steel, zdp, would have to be held for days to get toughness up to small load batoning levels

[erotdaman]

minutes, seconds and hrc, ok. but Fahrenheit? i have learned english in school but the temperature unit is like listening to greek 😂 very interesting information. Thanks for sharing.

[asingleoat]

narex claims to austemper some (all?) of their woodworking tools and they've had great edge retention at low bevel angles for me

[benjaminseigal]

Thank you! Excellent info. So, would this be a good choice for a JS performance knife?

[abolfazlrastgar]

Is there any necessity to heat treatment high alloy steels like M2 in vacuum?

[sevazinhogamer]

Increasing toughness using martempering will also increase other strenghts like shear strenght and shear modulus? Whats the common property to specify the toughness of a steel? The UTS or something else?