Jump to content

Recommended Posts

OK, I just have this one question. I don't understand too much about this diagram or that one, I know heat it red, quench in warm oil, toss in oven at 350 for an hour or two:). But I wanted to ask, I hear about going through the hardening process(heat to NM, quench in warm oil) 3 times, supposedly refines the grains, therefore resulting in a tougher, better cutting blade/edge. Can anyone shed any light on this? Thanks.

Edited by Sam Salvati
Link to post
Share on other sites

Hi Sam !

i have seen what you speak about in a video from Andrew Jordan's (bladesmith from the Netherlands) website where he does this triple -"very fast" quench (more of a dip) 3 times to refine the structure in the steel... before the real hardening ...

He just dunks it in, takes it out (wait for the oil to flash) and back in the forge to get up to temp again !!! i don't know if he heats it up to NM but this is probably the case... I have never tried it yet ! still waiting for spring to come (of the snow to melt)

 

Here is a link to his website and from there you can find (at the bottom of the page) a link to an interview he gave to a TV station : He performs this step during the video... and it's in English.

 

He makes real nice knives, and it is a very instructive video... (at least i find it instructive)

 

http://www.jordanknives.com/

 

it is in Real Player format (you need real player to view it)

Link to post
Share on other sites

Cool thanks Steve, I meant going throgh the entire process of hardening 3 times, heating to NM and quenching, then letting it cool to room temperature, then heating to NM and quenching again, etcetera.

Link to post
Share on other sites

Yes, it works and it is worth doing.

 

 

 

OK, cool. Does it really refine the grain? WHat does it actually do? WHat benefits would the steel(let's say 1075 or 5160) actually expeirience?

Edited by Sam Salvati
Link to post
Share on other sites

Sam,

 

You can do a search here, on Sword Forum, on Bladeforums, and for Dr. Verhoeven's online book--all of which will save some people from rewriting a couple of pages that already exist out there.

 

Steve,

 

The video is cool. He has a very nice shop. IMHO, however, he doesn't really get the blade up to temp on the last two cycles, and is more doing pyrotechnics for the camera. He also had some pretty good fishmouth going, which I think he ground out:)

 

John

Link to post
Share on other sites

Sam,

 

You can do a search here, on Sword Forum, on Bladeforums, and for Dr. Verhoeven's online book--all of which will save some people from rewriting a couple of pages that already exist out there.

 

 

John

 

 

I have read into Verhoeven's book, I just would like it explained in a bit simpler terms. Verhoeven's book is GREAT, just a bit :wacko: sometimes.

Link to post
Share on other sites

Do the three post-forging quenches THEN NORMALIZE!

 

Have you experienced significant reduction in grain size by multiple quenching, enough to justify it? Very true, you could achieve grain reduction this way, and eliminate internal stresses through normalizing cycles afterward, but is it really better than just normalizing?

 

 

 

 

BTW Karl, were you at Ashokan last year? I'm wracking my brains trying to remember if I met you there, and it's driving me nuts! I spent a bit of time speaking to Jerry Rados (interestingly enough, about totally non-knife related things) , and your website mentions his prominence in your knifemaking.

 

Regardless, your website is fantastic!

Edited by Matt Gregory
Link to post
Share on other sites

The process dissolves the carbides without going to higher temperatures .The higher temperatures are good to avoid as they mean grain growth. Multiple normalizing also means smaller grains since each time you go through the austenite/pearlite change you create new [small] grains. Quenching will give smaller grains as the energy in the martensite gives more sites for nucleating new grains. More than 3x creates other problems you don't want. :mellow:

Link to post
Share on other sites

"More than 3x creates other problems you don't want."

 

More scale, more decarburization, lower hardnability as you get smaller and smaller grain. IIRC we had a good discussion of this with myself, Kevin Cashen and you over on sword forum ,a while back. :rolleyes:

Link to post
Share on other sites

...so, multiple quenching will offer reduced grain size over standard normalization techniques, or is it simply more 'foolproof' (I apply that term to myself often enough) than possibly going past Ac3 during the typical blacksmith's normalizing?

Link to post
Share on other sites

Mete, you say "lower hardenability" as though it were a bad thing! ;)

 

I know, I know, but the trick is knowing when to stop.

Edited by Alan Longmire
Link to post
Share on other sites

Mete, you say "lower hardenability" as though it were a bad thing! ;)

 

I know, I know, but the trick is knowing when to stop.

Well I was thinking of steels like 1095 where it might be significant and there is a diminishing returns thing as far as fine grain goes.. Of course in many aspects of life I could say that if you haven't made the point after three tries ,don't go further you'll only make a fool of yourself . :unsure: ....Matt, this is all about nucleaton and grain growth. Normalizing gives you a certain number of nucleation sites ,quenching would give you more .Cold working in the pearlite range would give you more also.

Link to post
Share on other sites

Don't use the word 'packing' it's a MYTH !! As you drop below the austenite range you get either pearlite [slow cool] or martensite [fast cool]. Sam , you need to do more reading !!

Link to post
Share on other sites

....Matt, this is all about nucleaton and grain growth. Normalizing gives you a certain number of nucleation sites ,quenching would give you more .Cold working in the pearlite range would give you more also.

 

 

Thanks,mete! Interesting... none of this was mentioned in Verhoeven's text, which I finally managed to slog through. I'm stunned that I haven't managed to stumble across it anywhere else (other than the obvious!). Does anyone have a link to a thread or something that might give me a bit more insight? I find this stuff fascinating, but there are not too many centrally located sources for this information (at least, other than Verhoeven's paper or that I've managed to find in the last 5 or 6 months).

Link to post
Share on other sites

On one of Ed Fowler's videos about forging 52100, he says that he quenches three times with a 24 hour wait between each quench. He claims that the knife will have more cutting/edge holding performance than one that is quenched three times in one day.

Link to post
Share on other sites

Fowler does not deal with science ! ...When we go from austenite to pearlite/martensite or go in the opposite direction grains are first nucleated then grow . Points of nucleation are often grain boundaries .There is physically more room in grain boundaries for things to happen and things [various elements like V or bad guys like phosphorous] collect there. The atomic lattice when disturbed has what are called dislocations .These too are nucleation points both from an energy standpoint and because of the increased spacing between atoms...So - the more nucleation points [finer grain to start with] martensite, cold work , the more nucleation points -and that results in more and finer grains. We go back and forth across the transformation getting finer grain each time !! When we finally get to the hardening stage the final grain size is then dependent on the austenitic grain size at that point. :D

Link to post
Share on other sites

Thanks,mete! Interesting... none of this was mentioned in Verhoeven's text, which I finally managed to slog through. I'm stunned that I haven't managed to stumble across it anywhere else (other than the obvious!). Does anyone have a link to a thread or something that might give me a bit more insight? I find this stuff fascinating, but there are not too many centrally located sources for this information (at least, other than Verhoeven's paper or that I've managed to find in the last 5 or 6 months).

 

I understood all of what Mete is talking about from Verhoeven's paper, a whole chapter dedicated to it.

Link to post
Share on other sites

I understood all of what Mete is talking about from Verhoeven's paper, a whole chapter dedicated to it.

 

Guess I need to review it, eh? I would be a great deal like me to miss it entirely, or just fail to fathom what was being said until after it's pointed out to me! No doubt part of the problem is the amount of time it took me to get through it... I'm sure half of it has been lost to me already.

 

Regardless, thanks for your patience, you guys! This stuff is not very light, or easy to absorb -- and those of us that have no technical background struggle with a lot of this!

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...