Case Hardening 101 - Heat Treatment Oversimplified

G'day everyone,

In a recent project I had to case harden some low carbon steel in order to raise the carbon content, so that I could quench harden it. I got a few questions about the method that used. In this video I would like to show you some of the test parts that I did before I case hardened the vise, as well as some of the improvements that I have made to the method. I hope you find the video useful.

#machining #heattreatment #casehardening

Timestamps
0:00 - Introduction (What is Case Hardening)
1:02 - Applications For Case hardening
4:01 - Carburization
6:14 - Pack Hardening
11:15 - Quenching and Normalizing Steel
13:59 - Water and Brine Quenching
15:14 - Sodium Carbonate + Charcoal

[jeffmolatore]

I studied metallurgy for years in college and after. I rarely see YouTube presentations of heat treatment without misinformation. You did an accurate and clear job of presenting a complex subject and it was entertaining.

[russbilzing]

An old machinist showed me several methods of case hardening for plow points and the like, harking back to "olden days" before cars and such. My favorite was an iron box filled with small pieces of bone and antler, which was supplied by my breaking up dead critters. The box was about 3/8ths of an inch thick, which closed with a snail cam. He would then chuck it in the forge and I would get to work pumping the bellows to his satisfaction. I was pleased to stop when he figured it was time enough and he would let the fire die for the night. In the morning I would drag out the box and empty it. The hardening usually brought out some colors on the parts. For the tempering, he used rendered bear fat because it would not crack or check the metal. Just thought I might mention a different method. Good video, thanks.

[kramerdesign]

I had no idea the sodium carbonate and brine solution could make such a big difference! Super interesting and well presented!

[braddeyoung]

I learned 10 times more about case hardening from your video than I learned from my 3-month heat treating course at technical college.

[joshclark]

"Traditionally you would use wrought iron, but we no longer live in the 18th century" 😂 I'm so glad you're able to take advice from others and admit some mistakes. That's a very hard thing to do. You weren't bad with your method though and in your case I think case hardening would be a good idea. You definitely do a ton of research to find different methods for doing a thing, their effectiveness, and problems with them, and weigh the cost and labor for each of them. It's only natural to miss the occasional detail but I honestly think you do a fantastic job on your research and it's very insightful to listen to! And of course you do test things for yourself so you're not just relying on book knowledge and know that slight adaptations you make will still produce the same result. Well done!

[josels]

I’ve heard about pack carburize but I have never done this. Back in the mid 90s I got a job at a local commercial/tooling heat treatment shop. I first started running the salt pots running tooling O-1, O-6, S5 and many more tooling materials. It was a salt to salt or salt to oil process. I moved on to run the vacuum furnaces, temper and endo furnaces. At least a few years in Each department. After 10 years of working in this tooling shop I decided I wanted to learn more and ended up getting a job at the words biggest heat treatment companies (BTP) this was one great experience that I will always be grateful for. I started as a vacuum operator, moved to a temper furnace operator, Nitride supervisor, shop foreman, production manager and finally plant manager. All these jumps was within a 12year time period not overnight. By this time I had 22years experience and made a decision to slow things down, I moved back to my first job as a facility manager. I am now in charge of the furnaces and future development of the plant. But I always love to hit the floor and reach the new guys a few tricks, especially the guys that show interest in the process.

But getting back to carburize, I’m not to familiar with pack carburize since this is not allowed in aerospace parts. We process the parts in a furnace with temperature and carbon controlled instruments. But for a tooling part this seems to be good enough, if it fails you just try again.

I might make some videos on the process using controlled instruments. I’ll see if I have time this year.

[thethj]

This is a compliment, this will save me a lot of time, I enjoy reading however work takes mostly all my time, and a lot of times I just need the answers to the test fast, this was a great thing you are narrating, and illustrating and will save me and others time and that money thing we need, and it's always a topic I am interested in too. You have from day one provided me with all like-minded topics and interests thank you for all you do hope to see more. Good day to you.

[Preso]

Without really knowing what I was doing, I managed to case harden some model locomotive parts using almost exactly the same process you've shown. I did use the sodium carbonate too. I've read that old fashioned blood and bone fertiliser is a good source of carbon but most modern fertiliser has other additives and I wouldn't trust it. Apparently, boot leather can also be used. Good video on a not widely documented topic.

[euclidallglorytotheloglady]

It's great seeing the amount of skill and knowledge you've improved over the past year alone! Keep it up!!

[harmlesscreationsofthegree]

The quality of your vids increases every time. Your explanations are cogent and concise and I’m really glad I found your channel 🙂

[TradeWorks_Construction]

Thanks for the great overview and taking all the time to do the comparison testing. From personal experience I know how much time can be consumed by experimentation to validate the things people suggest.

Not to mention the exhausting effort needed to comb both old literature and pinpointing the specific relevant information amongst the mind boggling plethora of search returns that only pertain to the general topic your searching.

You may have called it a simple introduction but from my perspective even without covering some of the finer points on the subject, you did a fantastic introduction/Q & A that would help over 95% of the people wanting to case harden parts, 🍻.

[steved]

I watched with fascination and awe at you making the video on small home machinery and made comment to such . But boy you just took it to a whole new level in this video you are very informed and pass that knowledge over easily Thank you for such facinating content

[siyaindagulag.]

If you are stuck for flat bar, try old leaf spring steel .Though it can't be guaranteed as 0.7% C., (eutectoid), it's superior for hardness, tensile, etc.tjere are colour charts available if you've no thermocouple or welders crayon for the heat treat.your quench method is fantastic .evens out the chill crystal structure.
* still will require normalizing. 250° /hr/cubic inch.
Great vid man.

[dwightcarlson]

Excellent video! Real world hands on demonstration.

[ls]

Excellent video & discussion! From time to time, a case hardened part is far more efficient to make and use for my needs. Thanks for taking the time to better explain the process.

[bDwS]

This was a great guide supplement! Tells you quite a lot of info that tends to get skipped over in step by step guides and has a lot of good suggestions to make everything just work more smoothly! Really looking forward to trying this out !

[CraigsWorkshop]

That was brilliant - you've obviously done a ton of research, and I learned a lot watching. Thank you.

[rocketscience]

Great Video. As a chief engineer in the gas turbine industry I have designed many heat treated nickel, cobalt, steel, titanium and aluminum based super alloys parts, but I don't normally don't get to see the step-by-step details of how the process works. All beatings in the gas turbine world get case hardened mostly using M50-Nil as the base alloy. Even in ceramic bearings, the inner and outer races are still case hardened steel.

[christophnohtse]

When quenching a part, you should move it rapidly in the quenching medium, regardless what it is. Move it in a figure of 8 or circles and up and down. This movement prevents the steam jacket. If only a section of an part should be hardened, move the part up an down, to achieve a smooth transition from hardened to not hardened material.

[mp]

I have done my fair share of heat treatment case hardened or other you will never eliminate distortion. It is simply part of the game especially on intricate parts with variations of thickness such as your vice. I would say you were successful in the end. Quenching in water regardless of movement up or down or side to side the rate of change in temperature is extremely fast. Oil drops the rate of change more slowly but you would still experience distortion. I love the fact that you are not shy about trying new process and procedures keep up the good work.