heat treating

[tablesawtom]

This is a continuation from a post about micro bevels which got into an off topic about carburizing steel. To understand what is being said please read that post and view the two videos.

I found it interesting that in one, the parts were incased in clay. Both of the videos are correct although I question the angled and slow quench.  In both videos oxygen is kept away from the steel. In the red stage, in an open air environment the steel will start to decarb.  You can see a black film start to develop immediately. Decarb is the term used to describe that process in my neck of the woods. If allowed to continue it will flake off and degrade until useless. The box that is used to carburize in Timberwolf's video will self destroy its self after a while and will have to be remade. Basically both methods are a different form of the same thing. And time at temperature will dictate how deep the case goes. Whenever I did it it was with a special purchased high carbon material so I cannot say anything as to charcoal or burnt leather.


There are also atmospheric furnaces that can surround the steel in a high carbon atmosphere ( keep oxygen out) And it can get quenched right from the furnace. The quench in water must be straight in and as rapidly as possible. Uneven quenching will cause one side to cool more quickly and the part will bend.

What Timberwolve said about carburizing all the way through is possible but it is not cost effective.  It is a great razzle dazzle though, and great for him because if anyone can pull that off it would be him.. In his video, the box was in the furnace for 8 hours at 1650 degrees and then cooled in the furnace overnight for a .050- .060 case. Usually a piece is carburized when a part needs to hard on the outside but softer on the inside, so it is beyond me why anyone would do it all the way through.

Here is the tricky part. What Timberwolf said about re-hardening some Marple chisels is correct but only if the steel in question is Oil hardening. A lot of chisels are water hardening. Which is a W1-W4 I believe but not for certain on how many numbers.. Lie Nielsen's are A2 or air hardening. If the steel is water hardening and one quenches it in oil it will not get as hard as it should.  A2 will not like oil and O1 will not like water. If you are going to try it I would test it on a chisel you do not mind getting destroyed first.

I am reaching back 20-30 years but I think S7 is the only tool steel that is either air or oil hardening. and the oil is for large pieces.

Am I discrediting Timberwold? Not in the least. He is very knowable in our area of expertise. I taught a 3 credit course in heart treatment at a community collage for 5 years and today with everything considered, and because I no longer have everything I need, I would not attempt heat treating anything, I would send it to a heat threat shop. 

My advise is unless you know for sure what type of steel you have don't do it. Also a lot of research before proceeding. 

Tom

[AHill]

The Clickspring videos Timberwolf linked to are generally technically correct. In the one where he carburizes the steel rods and then tempers them, there's one slight terminology issue I have. He calls the steel "tempered martensite." In actuality, when you temper martensite, you are changing the crystal structure of some of the martensite to cementite, which is not as brittle as martensite. Martensite has a higher carbon content than cementite, which is partially responsible for the increased brittleness of martensitic steel vs. cementite. Martensite crystals are needle-like compared to cementite, which is orthorhombic. So, it's both the carbon content and the crystal structure which affect hardness.

Heat treating can get to be fairly complex from a chemistry, physics, and thermodynamics standpoint. In the old days (like ancient blacksmiths, bladesmiths, etc.), this was all discovered empirically (by observation) and the knowledge passed along to successive generations of tradesmen. Once the science of it all was defined, a renaissance of sorts took place in the industrial age where more exotic alloys were created, where different elements were alloyed into the steel to affect the crystal structure, alter the time and temperature of transformation, and either remove or create compounds that benefit the steel's application. These discoveries and understanding of the science are what gave us many of the steel alloys we use today. W1, O1, A2, D2, M4, PM-V11, etc. All were created using the knowledge of how the science works.

[tablesawtom]

I was wondering when Allen was going to show up. That is why I put the disclaimer about there being  a possibility of 4 different grades of water hardening tool steels. And I don't remember where pearlite fits in. I thought my post was getting kind of long so I stayed away from the TTT curve.  A2 has a long TTT curve verses 1060which is very short. I do know that there are 4 distinct stages in a quench and quenching in water they are most notable. I said that so, I could say this that the hardness isn't complete until at the very last stage. A2 is when you can hold it comfortably in your hand. With this in mind cryogenically taking A2 to a much lower temperature increases the hardness. A2 for example usually hardens to about 63 Rockwell C but gets harder when the temperature of the steel drops to the temperature of liquid nitrogen. And to my knowledge it also changes the grain structure. Hardeninf and tempering are two completely different process.

PM-V11 is in the powered metal range. I do not know if it is sintered like carbide or not. I do know that the powered metals I have experience with do not abrade very well and Aluminum grinding wheel takes a long time. It seem that that type of steel likes a ceramic wheel. I bought a 2 inch plane blade form Lee Valle the other day so I am sure I am going to find out if it likes CBN wheels. 

Tom

[adamcherubini]

Here is the tricky part. What Timberwolf said about re-hardening some Marple chisels is correct but only if the steel in question is Oil hardening. A lot of chisels are water hardening. Which is a W1-W4 I believe but not for certain on how many numbers.. Lie Nielsen's are A2 or air hardening. If the steel is water hardening and one quenches it in oil it will not get as hard as it should.  A2 will not like oil and O1 will not like water. If you are going to try it I would test it on a chisel you do not mind getting destroyed first.

Just want to add, quenching with oil or water isn’t as clear cut as always quench W-1 with water. How hard, and how much martensite you end up with, and how deep that martensite layer is, all can be manipulated by the recipe of the quench.

I’ve used engine oil effectively to harden a range of different types of steels including w-1.

[Timberwolf]

This is a continuation from a post about micro bevels which got into an off topic about carburizing steel. To understand what is being said please read that post and view the two videos.

I found it interesting that in one, the parts were incased in clay. Both of the videos are correct although I question the angled and slow quench.  In both videos oxygen is kept away from the steel. In the red stage, in an open air environment the steel will start to decarb.  You can see a black film start to develop immediately. Decarb is the term used to describe that process in my neck of the woods. If allowed to continue it will flake off and degrade until useless. The box that is used to carburize in Timberwolf's video will self destroy its self after a while and will have to be remade. Basically both methods are a different form of the same thing. And time at temperature will dictate how deep the case goes. Whenever I did it it was with a special purchased high carbon material so I cannot say anything as to charcoal or burnt leather.


There are also atmospheric furnaces that can surround the steel in a high carbon atmosphere ( keep oxygen out) And it can get quenched right from the furnace. The quench in water must be straight in and as rapidly as possible. Uneven quenching will cause one side to cool more quickly and the part will bend.

What Timberwolve said about carburizing all the way through is possible but it is not cost effective.  It is a great razzle dazzle though, and great for him because if anyone can pull that off it would be him.. In his video, the box was in the furnace for 8 hours at 1650 degrees and then cooled in the furnace overnight for a .050- .060 case. Usually a piece is carburized when a part needs to hard on the outside but softer on the inside, so it is beyond me why anyone would do it all the way through.

Here is the tricky part. What Timberwolf said about re-hardening some Marple chisels is correct but only if the steel in question is Oil hardening. A lot of chisels are water hardening. Which is a W1-W4 I believe but not for certain on how many numbers.. Lie Nielsen's are A2 or air hardening. If the steel is water hardening and one quenches it in oil it will not get as hard as it should.  A2 will not like oil and O1 will not like water. If you are going to try it I would test it on a chisel you do not mind getting destroyed first.

I am reaching back 20-30 years but I think S7 is the only tool steel that is either air or oil hardening. and the oil is for large pieces.

Am I discrediting Timberwold? Not in the least. He is very knowable in our area of expertise. I taught a 3 credit course in heart treatment at a community collage for 5 years and today with everything considered, and because I no longer have everything I need, I would not attempt heat treating anything, I would send it to a heat threat shop. 

My advise is unless you know for sure what type of steel you have don't do it. Also a lot of research before proceeding. 

Tom

.................
The machine shop I was trained in was a "job shop"...that is the boss took in almost anything that came through the door, in order to meet payroll and keep the doors open. This was right after WWII and parts that were not available because of the war, had to be repaired or made from scratch. I was 14 years old.. Boss also held a patent on cement block machinery which we also manufactured and shipped all over the world. Parts of that machinery required they be hardened and for that we used cyanide. Cyanide is nothing to fool around with recklessly. We also repaired cracked engine blocks, cylinder heads, large boat shafts, propellers etc...and lots parts for high speed racing boats. I found the work extremely interesting and I still do after all this time.

As a hobby, I love to experiment with metals and like to make wood carving knives out of exotic wood and unknown types of scrap steel and steel that I purchase, like 01 and W1, but most of what I know about it, is what I have learned by experimentation over more than 70 years. I have many more than a dozen types of sharpening equipment, some factory made and some I have designed and made myself. As far as hardening chisels or other edge tools, I just feel like if they won't hold an edge that is acceptable TO ME, it is junk anyway, so I am out nothing when I attempt to salvage it. So far I have never been too disappointed. I have hardened knife blades 0-1 in water and W-1in oil..in doing so, the temperature of the steel is most important, for this I use an oxy-acetylene torch...but I can also do it in a BBQ grill, charcoal briquets and a hair blow dryer....One thing I learned early on....If you think you can't do something, you are defeated before you start..you will never really know what you can do if you don't try.... "Can't" never could do anything...

[Tony Z]

Jack, you will appreciate this tale: when I started my manufacturing company (1989), I had tooling made by a small company about 45 miles north. I had an order for parts, but the tooling kept breaking, and we were running late, about to lose our first customer. The kid I hired was a junkyard dog, and he knew as well as I did the peril of losing our first customer. I had a Sheldon 7" lathe, and the kid said he would run home and take a tie rod off of one of the cars he had junked around his parent's home to make a replacement punch, that had broken. I said I would go home and swipe my wife's toaster oven to make some sort of attempt at hardening.

Long and the short of it, was he did a somewhat acceptable job of turning a punch on the 7" lathe, and we didn't further damage it in our attempt at heat treating in the toaster oven. We successfully completed and shipped the order.

That was more than 30 years ago and I look at the equipment we now have, and still so much is dependent upon the ability to just try something, even if it doesn't follow a text book.

[Admiral]

I just love reading all this; heat treatment is way, way out of my wheelhouse and I'll likely not attempt it, but all the different opinions, methods and musings are very interesting to me nonetheless. So thanks to all who contributed to this thread!

[Tony Z]

I just love reading all this; heat treatment is way, way out of my wheelhouse and I'll likely not attempt it, but all the different opinions, methods and musings are very interesting to me nonetheless.  So thanks to all who contributed to this thread!

If you're ever coming across I-80, through PA, ping me and I'll have someone teach you all you don't need to know!

[Admiral]

If you're ever coming across I-80, through PA, ping me and I'll have someone teach you all you don't need to know!

Will do, but honestly I've never driven west of Lewisburg PA on I-80 (my bride went to college there, class of '74) and as I recall, DuBois is perhaps a couple of hours more down I-80; but from my place in NJ, all I have to do is get on I-80 and make a left! 

But then again, you never know, when I retire (was going to in 2020, then covid hit and since I didn't have to commute to work I just kept working) I might get hankering for a road trip!

[Tony Z]

Will do, but honestly I've never driven west of Lewisburg PA on I-80 (my bride went to college there, class of '74) and as I recall, DuBois is perhaps a couple of hours more down I-80; but from my place in NJ, all I have to do is get on I-80 and make a left! 

But then again, you never know, when I retire (was going to in 2020, then covid hit and since I didn't have to commute to work I just kept working) I might get hankering for a road trip!

Yes, a couple hours west of Lewisburg. I was a Penn State grad in '74 and am not planning on retiring (I own the place and do what I want to do!). Wife is a few years younger and might retire in the next year or three.

We make parts from powdered metal, with the majority of parts going into new cars.