Triple quench secrets to be revealed?(or not)

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In my limited amount of forging , though not blades, I always struck the same number of blows on each side , seemed obvious to me to keep things straight. But if it isn't so obvious to others we should state it..... Temperatures between 700-1100F metallurgists call stress relief treatment, and above 1100F to the critical temp we would call a subcritical anneal.... Bladesmith normalizing is subcritical ,metallurgists normalizing is about 100F above the critical temp..... I see from data I have that MAXIMUM forging temp for 52100 is 2100F. I would never recommend that, things like grain growth occur rapidly above 1700F.
 
Mete
steel is molting when made and way over
critical at that time, why not the grain growth then?
 
Our latest methods are still in the experimental stage, waiting for the lab to report back.

The stuff we were doing when the test blade reported in Blade Magazine was worked up were as follows:

An old rhyme has guided me for years, even before I heard it from J D Smith.

"If thou wilst a keen edge win
forge it thick and grind it thin"

After the forging was complete, two blade smith normalizing heats:
heat to critical, confirmed by a magnet, hold blade in a shaddow, it will turn dark, then brighten, then reheat to critical again, be careful to keep the tip from over heating and cool the blade in a shaddow, watch the the colors change again. The blade will be magnetic at this point.
Full normalize heat, to critical, check with a magnet and allow to cool to room temp. in still air. Don't hurry it let it cool slowly.

Then three blade-smith anneals (that is what I call them). Heat to 800 degrees, hold for two hours and let them cool down slowly. (I do this in three days, 24 hours between heats, in the house hold freezer over night.

Many question the 24 hour cycles, I use them because I believe in them, steel takes time to enjoy where you want it to go, tincture of time has never hurt.

Grind the blade evenly, right side, left side.
Take the blade to a 220 grit finish. Any deeper scratchs can influence the grain structure below the scratch.

Texaco Type A quechant is the oil I use for 52100 and 5160. You can purchase some from Shane Justice. If you use any other oil we are not on the same page.

The specks call for heating the oil to 135 f. I speed my oil up just a little by heating it to 165 f. (I experimented with oil temps a lot to figure this out, you may need to experiment on your own to find what works best for your blades.)

Heat the blade to critical, catch it right at critical or a little above, if you allow it to cool, it will remain non magnetic but be too cool to harden. Use the magnet religously!
Quench the blade in the oil to the depth you wish to harden. When it quits fuming, fully submerge the blade in the oil and allow the oil and blade to come to room temp. Blades then go back to the home freezer overnight. I try to keep 24 hour cycles. repeat the quench cycle for a total of three quenches.

I then temper the blades, again three cycles 24 hours apart. I believe that more time between cycles would be of benefit, but remember we got to make a profit!

The first tempering temp is 330 f.
Grind off a little of the edge flat to get to the best edge possible, then grind the blade to its final edge.

I test this edge, edge flex, then cut. If the blade chips on the flex test, I temper higher. Depending upon the nature of the chips I may to as high as 10 degrees for the next three tempering heats. Then test for chip again, if it chips try a higher temper temp. if not, test for cut.

The nature of the blade dictates how you need to treat it. It leads you through, if you try to lead, she will let you down.

The above is the basics, we can go further if we chose.

If you have seen the Bowie in my advertisment in Blade with the close up of the tip over the blade, you will see a blade that was plushed to the limit, (at that time). Only four men who looked at her had any idea what she was. The methods used on her were based upon advice from a fine gentleman who I met years ago, He was in his late 80's, had forged steel since he was 14. He had just solved a problem for what was then a fledgling company. The men of science could not shape the tool, he figured it out in a few weeks.
I asked him how? He smiled and said "Thermal Cycles". Thermal cycles and time have kept me interested in the forged blade, I see no end in sight.

WE have an unlimited number of variables that can influence the nature of the blades you complete, pay attention to everything, keep notes and only one major rule, enjoy.

There are many who will take pot shots at you when you explore, do not let them discourage you. You must be your greatest critic, this is the satisfaction that remains.

I did not get to the above on my own, Bill Moran taught me the basics of forging in such manner that I had more qustions than answers, and still do. This is the mark of a great teacher. Wayne Goddard taught me a lot about testing. Rex, Doc. Bill Burke and I have been working this stuff out for years and we still have places to go.
 
Ed, what does over night in the the home freezer accomplish besides a place to sit for the 24 hour cycle you mentioned above?

RL
 
Roger I'm thinking it's the time setting but again my thoughts
as before

ED
can I put your last post in the knife making site?
Thanks Dan
 
RL:
With some steels the 24 hour stuff may not make much difference. With 52100 and our mentods it does make a difference. Rex explained it to me, and has worked with some other steels with intersting results. This is how I remember his thoughts.
If you will excuse some big words, Martensite is the most relaxed form for hardened steel, retained austenite wants to convert to martensite. This takes time. Blades that were hardened 100 years ago will not be the same as they were when hardened. In order to achieve stable blades we need to eliminate retained austenite as much as possible. On our test blades with the 24 hour cycles there was no measrurable retained austenite.

I had a large camp blade that at first failed to harden through the multiple quench and tempering. She would not cut. I tossed her in the snow outside, she laid there all winter.
A hired had found her this spring and brought her back in the shop. I polished her up intending to etch her and see was I could see. I forgot her, Bill Burke came down this spring, found her and wanted to know why she was being ignored. I told him she would not cut, he put an edge on her and she cut with the best. I do not know what happened with the first part, she would have been very valuable in the time I had in her and I hatted to loose her. She came around on her own. I have been intending to send her to Rex for his opinion, but more important stuff is in the mill now.

That is part of why. This seemingly trivial system works, I accept that and encourage others to give it a try.
 
Greymaker, molten steel is poured into an ingot mold.Then it goes through a series of rolling, annealing , normalizing etc treatments. Whatever is necessary for the particular steel. Grains are formed and reformed . But the end result, the steel you buy, must have a resonably small grain since grain size is so important especially as far as toughness. BTW i explained to someone last night about the Titanic. The steel had 3 problems that made it very brittle. One of those was large grain size. A modern steel such as HY 80 would never had the brittle fracture. Grain size has importance in many applications.
 
Ed, thank you for that detailed reply. The story of the retrieved winter blade was interesting.

The 24 hour wait between quench, even for a particular steel, intrigues me.

Thanks again. RL
 
Originally posted by mete
... But if it isn't so obvious to others we should state it..... Temperatures between 700-1100F metallurgists call stress relief treatment, and above 1100F to the critical temp we would call a subcritical anneal.... Bladesmith normalizing is subcritical ,metallurgists normalizing is about 100F above the critical temp.....

mete:

If it is worth anything, some call me a bladesmith and I concurr with your definitions of stress relief and subcritical anneal.I normalize at or above the critical temp. and cycle with some thermal treatments at or slightly below critical. And I have never had a formal metallurgy class. I am not sure where the term "bladesmith normalize" originated from, but it cannot be universally applied.

I have a sceptical mistrust of people who have various letters following their name (BS,MD,PHD etc...), to me those letters just say that they can recite the lines that have been spoon fed to them. but I would much quicker put my money on the advice of experienced metallurgists than some of the stuff I have heard from bladesmiths over the years.

Some things have to be adjusted for blademaking techniques but for the most part, I'm with you;)
 
I have lost track of the test pieces. I would like to get them back and send them to Rex and have them tested for grain size, martensite and any retained austenite that may be present. Or they can be sent to any other lab but lets finish the test. I can also sent the last piece to where ever. Do you want it first RL?
 
Originally posted by Kevin R. Cashen
I have a sceptical mistrust of people who have various letters following their name (BS,MD,PHD etc...), to me those letters just say that they can recite the lines that have been spoon fed to them. but I would much quicker put my money on the advice of experienced metallurgists than some of the stuff I have heard from bladesmiths over the years.
It is as fair to be skeptical of degreed people as it is to be skeptical of bladesmith's and stock removal maker's claims.

It does seem that the more letters a person has piled up behind their names (and the more they advertise as much), the more they seem to relish in their attempt to acquire status-through-study, and the less grounded in reality they seem to be. (The number of degree letters is inversely proportional to how many toes they have planted in reality.)

In every profession, in every walk of life... ability and motivation, like intelligence, conform to a normal bell curve ... from doctors to janitors.

"In seeking your advisor, you have chosen your advice." -- Jean Paul Satre.

Whew. That was a lot of philosophy. I need another beer. Which, this week, and on a more productive note, is a fine little brew from Breckenridge Brewing out of Colorado called Porch Swing Ale. Goofy name... I think it's a special run, but really good stuff if you like ales. If you try it and don't care for it, well, it was free advice... and you know what they say about free advice...
 
Bill I can Rockwell it but don't trust my opinion of grain structure, no experience there. Best all around if someone who can do both step forward. Soon I will be out of town for two weeks too.

RL
 
Definitions: As far as I know I started using the term Bladesmith Anneal. If no one objects, I will define what the term means to me.

The bladesmith's Anneal is a process including time and temperature designed to soften a piece of steel to the point that it can be ground, drilled or other wise worked as he deems necessary. The bladesmith anneal is utilized by the individual bladesmith to achieve the performance qualities he desires to achieve from that piece of steel. It is determined by trial and error and the decisions are dictated by the future knife according to purpose.

Like the tempering process, the knife leads through its performance, the bladesmith coaches.

Science can tell the bladesmith what he did, and classify the system to further explain what happened, all the bladesmith needs to follow is taught by the knife.

This is pretty much the idea, the process can vary with every bladesmith, and each batch of steel, in reference to purpose.

I would appreciate your input. If someone else used the term first they can claim juristiction and modify the thought if they wish.
 
After reading an email from my friend Shane, I have a question. Maybe this question has been answered before, but the thread is too long to go back and reread, so here goes...

In regards to soak time, If I understand correctly, soak time at critical (non-magnetic for us backyard Bladesmiths) allows the carbon to go into solution and be absorbed by the Austinite prior to quenching. Bringing the steel to critical/non-magnetic also errases any previous grain flow etc. and resets things in a granular sense.

Here is my question...
Will multiple trips into the "critical zone" add up into a sort of cumulative soak time? The reason that I ask is that on the the blade that I recently tested to destruction, during the forging of the blade I hit it with a ball peen hammer to see if it would leave a mark in the steel's grain (similar to Kevin's initials experiment). After 3 normalizing cycles, 3 annealing cycles and 3 quenching cycles, the mark still showed in the grain of the steel. It appears as a small round dot on the surface of the steel. I'm certain that the total of all of the steel's trips into the "critical zone" add up to well over 5 minutes of soak time, especially during the annealing cycles.

Can anyone offer an explaination for the remaining mark?

Sorry if it's already been covered in previous posts.

Rick
 
RL

OK I'll just send all the samples in and see what we get back. Do You Have the Other three samples? On another note.

I seem to recall reading somewhere that when a piece of steel is broken what you see is not the true grain of the steel but just an indication of the size of the grain in the steel. The piece has to be cut and etched to reveal the true grain size in the steel and is measured under a microscope. The method of measurement is to count the number of grains in a specific area of the steel. The grain size is then given as a size of 1 to 14 with 14 being the smallest on the chart. Industry standards for very fine grained steel being size 12.

Blades that we have sent to be sectioned and measured show a grain size of 5-6 in the spine 7-8 in the center and 8-10 in the cutting edge. This is after normalizing three times and anealing three times. BUT it is BEFORE hardening and tempering. Any one Have any sientific explanation of why this is?

Blades that have been measured AFTER heat treating have shown a grain size of 5-6 on the spine. the same size as the unhardened blade. Grain size of 8-10 is found in the transition zone and 10-12 just above the temper line or hamon if you prefer. The cutting edge has a grain size of 14 and finer with an even but randomly distribution of chromium carbide grains in a softer matrix of tempered martensite with no measureable retained austenite.

sorry for the length of this post
 
No, after heat treating and Rockwell testing I sent the 5160 test pieces to Mete for grain analysis. Both he and I posted the pictures of the fractures here.

RL
 
Thanks Dan, I'll see what it says.

BTW, did you reread this whole thread to find that or do you have a photgraphic memory? Either way, thanks.

OK Dan, I just checked out page 16 and nothing. I'm hoping you had a moment of lisdexia, oops dislexia, and you meant page 61. Going there next.

Edited to add.. After reading Kevin's post on page 61 (I thought Dan was sending me on a goose chase), he mentioned that the phenomenon works best with hypereutectoid steels at certain temperatures below ACm. Mine was accomplished with a hypoeutectoid steel (5160) with the steel at room temperature when I struck it with the ball peen hammer. Any ideas? Anyone?

Maybe I invented a new patterning technique. I'll work on the patent tomorrow, but for now consider it copyrighted;)

Rick
 
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