Quenching/metallurgy question

Wow, that's a heck of a post, Kevin. :thumbup: :thumbup: I think you hit the nail on the head.

Regarding the use of plates in marquenching, I've never messed with it for the reasons you've mentioned, but I believe Heinzelman Heat Treating does it on certain large parts (not knife related) as well as an outfit here in SoCal the name of which eludes me at the moment. I'm sure there are others, but these are two I've had dealings with in the past.
I think Paul Bos does something like that too.
 
Kevin R. Cashen said:
If you haven’t got to the metallography portion of your schooling, it is really cool:D . Preparation is painfully boring but the viewing is worth it.
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This summer :D

I have 5 courses this summer. 2 of them from May to June, 2 others from July to August and the other I don't know yet.

With this, I can't work full time AND I will have a whole semester working in the Industry next fall (hopefully in Biomaterials).

So I will probably have time to start making knives. And if I REALLY am lucky, I will be able to use the University's material for Heat Treating.

That would REALLY be cool.

Thanks to all for helping me and IronWolf, thanks a lot for that PDF.
 
Phillip Patton said:
Very cool pictures, Kevin! Especially the one of pearlite. I knew pearlite was called that because it looks like mother-of-pearl, but I never saw a photo that really looked like it. That one is great. It looks a lot like MOP. It's got all the colors and everything. Did you do that one yourself?
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It lost all the details scaling it down for the internet:(. I just took that photo last night, and I have quite a few more I am working with right now. I have a whole series from a cross section of Japanese sword that I am sorting through which will show the transitions and structures from the very edge all the way to the spine (the funnest part for me was slicing that sucker up;) :D ). With a combination of felt, cloth and leather wheels, I am finally able to get above a 50,000 grit polish and bring the structures out. The pearlite is really breathtaking, I have some images that show really great sub-grain formation of pearlite within prior austenite grains, demonstrating clearly how one grain will spawn multiple smaller grains with jsut cooling. Now that I am fine tuning the metallograph it is a matter of pride to only use my own images:) .
 
Kevin R. Cashen said:
The pearlite is really breathtaking, I have some images that show really great sub-grain formation of pearlite within prior austenite grains, demonstrating clearly how one grain will spawn multiple smaller grains with jsut cooling. Now that I am fine tuning the metallograph it is a matter of pride to only use my own images:) .
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You absolutely cannot make a statement like that and NOT share the images!!! For crying out loud, you can be cruel sometimes!;)
 
This thread is turning into a Metal-Porn thread :D




Maybe another little question on quenching and general HT. What would you do different for a small fixed blade EDC (3-3.5" blade), for a mid-size knife (4-5" blade) and a big chopper (7-9" blade), considering the steel being the same?



I hope I will be able to make some knife related metallurgy and get credits for it(at school I mean). Like heat treating my blades, making powder steel or any other steel by myself, maybe make and understand how Damascus Steel works. I'll start by reading Mr. Cashen's stuff :)
 
Here is but one example of what I was talking about at around 500X.

pearlite.jpg


You can see the prior austenite grain boundary since I used heat treatment to fill it with iron carbide (something you don't normally want) and inside you can see the new pearlite "grains" that have formed when it cooled to around 1000F. The pearlite reaction likes corners and nooks that have high potential energy and you can see how the individual colonies are centered on such areas in the grain boundaries. As one approaches 1000F. a film of proeutectoid cementite (carbon beyond .8%) will form out from the point of high energy where it initiated. The formation of this lamellae will create carbon depeated areas to either side which will cause the formation of ferrite bands, these ferrite bands will create higher concentrations of carbon which will become yet another cementite lamellae and so on, and so on...

The nital attacks these lamellae at different rates causing facets that scatter light in very different directions and that is why you get the mother of pearl effect. But in this image the boundaries between the different pearlite colonies are clearly seen within the prior austenite grain. If that nasty cementite fence was not there on subsequent reheating a whole new set of austenite grains would begin to form within those pearlite interfaces and you would get many more fine grains. So when you heat a piece of steel, cooling it will form new crystaline zones and then heating will do it again, making several opportunites to refine things in just one cycle.

I had to chuckle about the idea of this being metallurgical porn since there is so much truth to that statment. Perhaps I could set up a live cam on my old trinocular scope and if you guys paid up I would scan anywhere on a blade you asked me, for the right money;)

I don't work too much with 52100 so the only stuff I have examined was not mine so I will wait until I can cover my own stuff.
 
Lots of things happen at the grain boundaries , good and bad .There is physically more room at the grain boundaries so they tend to collect bad things like phosphorous and good things like vanadium. Grain growth involves the movement of grain boundaries and things like vanadium and columbium in the boundaries slow the movement thereby 'refining' grain....If you look very closely you will see pictures of Kevin, that's what he means by "my own images " !!
 
mete said:
....If you look very closely you will see pictures of Kevin, that's what he means by "my own images " !!
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You mean like one of those 'Magic Eye' things where you need to stare at it with your eyes crossed and de-focused?

Rats, I suck at those...:D

Cool image, Kevin... are you planning on showing a lot of these, or were they taken more as exercises in your constant research? I'm sure it goes without saying, but I for one would love to see one every once in a while, with a brief explanation of what I'm seeing and how to (or not to) achieve it!
 
MrPurple said:
You mean like one of those 'Magic Eye' things where you need to stare at it with your eyes crossed and de-focused?

Rats, I suck at those...:D

Cool image, Kevin... are you planning on showing a lot of these, or were they taken more as exercises in your constant research? I'm sure it goes without saying, but I for one would love to see one every once in a while, with a brief explanation of what I'm seeing and how to (or not to) achieve it!
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They are for sharing and discussion. I am developing a collection of them so that I can use them for the web page, and discussions both here and at my table at shows. I like to show off my knives too, but right now this business needs information about what is really going on inside the steel much more than it needs another knife photo.

I think all of us have at one time or another got a twinge of guilt or paranoia when we scanned a image out of a book because we needed to show somebody something. My metallography has finally reached the point that liberates me from all that since I can now generate any desired image at will and do whatever I feel like with it since it is all mine. I may throw some sort of copyright not on them, not becasue I don't wnat folks to use them, but I think giving credit to the source is only right and some folks need a reminder of that occasionally.

I am doing metallographic analysis of mine and others work but as I previously mentioned it is boring when things are heat treated right. I really have to abuse the steel in order to get these other formations to come out, but the experience gained in learning all the temperatures and treatments in order to produce them is invaluable.

If anybody here will be at the Badger Knife Club Show this weekend in WI, feel free to stop by my table and talk, I will have a pictorial of the sliced up sword with me.
 
I had to chuckle about the idea of this being metallurgical porn since there is so much truth to that statment. Perhaps I could set up a live cam on my old trinocular scope and if you guys paid up I would scan anywhere on a blade you asked me, for the right money;)
Kevin you will be properly clad for the metal porn I assume. No Madonna style
metallic clothes I hope! :eek:
 
In the Ebook, Verhoeven mention another book, the Heat Treater's Guide. It was also mentionned by one of my teachers.

Any of you guys know/own that book?
 
cybrok said:
In the Ebook, Verhoeven mention another book, the Heat Treater's Guide. It was also mentionned by one of my teachers.

Any of you guys know/own that book?
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I've looked into getting that book, and it is a bit on the pricey side...maybe someday. I do have a 1971 edition of "The Making, Shaping and Treating of Steel" by the US Steel Corp. It is a great book with a lot of references, diagrams and such. I still have a buch of exploring to do in that one yet. I'm sure the library will want that back sometime, I've had it checked out for 9 years! :eek: I think I'll have to wait for the "amnesty day" before showing my face around there again! -Matt-
 
cybrok said:
In the Ebook, Verhoeven mention another book, the Heat Treater's Guide. It was also mentionned by one of my teachers.

Any of you guys know/own that book?
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That book is the single most valuable resource anybody wanting to heat treat steel could own. But I am too cheap to have purchased the newest edition, which is in the hundreds of dollars. I have the 1982 edition which has all the really useful information and not all the fluff that apparently is worth a couple hundred more dollars. For around $35 used, I got the heat treating information on all the common alloys, and then ordered seperately whole books devoted to the other topics and still came out spending less.
 
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