Knife Talk Online Forums
  Home membership Help Search Calendar Members Classifieds Treasury Store Links Gallery Media Center Login Register  
Custom Search
Pages: 1 [2] 3   Go Down
  Send this topic  |  Print  
Author Topic: Jominy Test  (Read 8707 times)
0 Members and 1 Guest are viewing this topic.
ChrisAnders
Newbie
Trade Count: (0)
Sr. Member
*
Posts: 193


View Profile
« Reply #15 on: November 13, 2014, 05:37:33 PM »

I don't know that any egos will be stretched.  The various temperatures are influenced by more than just alloying, and that has been researched since the 30's if not earlier.  What are you using as the indication of the phase change?
Logged
Ed Fowler
Administrator
Trade Count: (1)
Hero Member
*****
Posts: 3451



View Profile WWW
« Reply #16 on: November 14, 2014, 06:22:06 PM »

I always use a magnet, while forging and heat treating.

I watch the phase changes as they cycle.

Results are judged by performance.
Logged

Ed Fowler High Performance Knives
http://edfowler.com/
ChrisAnders
Newbie
Trade Count: (0)
Sr. Member
*
Posts: 193


View Profile
« Reply #17 on: November 15, 2014, 05:40:27 PM »

What are you looking for to see phase changes?  

As an aside, below is a good video of a Jominy test, for those interested in exactly how it's done and what it shows.  This one has a rather odd initial hardness reading, which is explained in the description.

https://www.youtube.com/watch?v=qW0aUbTWtVM

« Last Edit: November 15, 2014, 06:41:18 PM by ChrisAnders » Logged
Ed Fowler
Administrator
Trade Count: (1)
Hero Member
*****
Posts: 3451



View Profile WWW
« Reply #18 on: November 16, 2014, 04:33:24 PM »

Thank you for sharing that Chris! This is the first time I have ever seen it happen, while the descriptions I have read were just as it happened, watching it was much more descriptive.

Rex decided to examine the influence of multiple quench on a Jominy quench. He found that the hardness progressed up the bar further with each quench.

It is nice to watch the phase change.
Logged

Ed Fowler High Performance Knives
http://edfowler.com/
ChrisAnders
Newbie
Trade Count: (0)
Sr. Member
*
Posts: 193


View Profile
« Reply #19 on: November 17, 2014, 02:43:53 AM »

Are Rex's findings based on new testing, or the original one we've been discussing?
Logged
Ed Fowler
Administrator
Trade Count: (1)
Hero Member
*****
Posts: 3451



View Profile WWW
« Reply #20 on: November 17, 2014, 04:27:53 AM »

The multiple quench was a different time than the first one described in this post.

Chris: You asked what I looked for in the phase changes.
First the magnet, when non magnetic I watch as the color goes from light to dark, then light again. Naturally it then turns darker.

I am not versed in computer stuff, what does &tsp; mean?
Logged

Ed Fowler High Performance Knives
http://edfowler.com/
ChrisAnders
Newbie
Trade Count: (0)
Sr. Member
*
Posts: 193


View Profile
« Reply #21 on: November 17, 2014, 02:17:05 PM »

Good question.  I don't know what that means.  I think it was added when I edited the post.  You don't happen to have any more details on Rex's work do you?
Logged
Ed Fowler
Administrator
Trade Count: (1)
Hero Member
*****
Posts: 3451



View Profile WWW
« Reply #22 on: November 17, 2014, 04:34:41 PM »

Rex and I ran many experiments for over 7 years, As I remember them I will relate them. For some reason my note books are gone, if I find them I will report what they contain.

We tested multiple quench up to 11 quenches. We did not 'wear out' the steel as some claim. We found the biggest bang for our buck was 3 quenches.

Forging at low temp and over 50 thermal cycles did not 'wear out' the steel.

Post forging quench from one to 7, again 3 was enough, 7 was not too much and was "happier" than 3.

The 1,725 Soak before going to work with a piece of steel was very significant for uniformity.

On some tests stress failure started with internal causes rather than surface failure.

Round holes in a blade are stress raisers. Be they in the top of the blade for a threaded thumb stud or in the side.

Any engraving or writing on the side of a blade (etched and laser cut included) can be a stress raiser. ie names, pictures numbers included.
They belong on the ricasso, this has been known since they started making swords and probably a long time before that.

If you profile a blade on an edm, you will leave stress raisers unless you grind over 1/3rd the depth of the marks of the cut away.

On a fully hardened blade saw teeth and file work are stress raisers. If the bottom of the cut is fillet it is not as significant as when the bottom of the cut is a sharp notch.

I could write a book on what we tried that did not work. There were many failures for each success, but looking back we learned from each failure and sometimes the failures let to success when working with another variable.


Logged

Ed Fowler High Performance Knives
http://edfowler.com/
ChrisAnders
Newbie
Trade Count: (0)
Sr. Member
*
Posts: 193


View Profile
« Reply #23 on: November 17, 2014, 11:54:12 PM »

I'm sure that generated a lot of information.  I should have been clearer.  I meant specifically the Jominy testing.
Logged
davidm
Member
Trade Count: (0)
Hero Member
***
Posts: 910


View Profile
« Reply #24 on: November 18, 2014, 02:50:07 AM »

It could be very helpful for this conversation and for documentation if Rex had an email contact. He is somewhat of a ghost partner in this..
Logged
Ed Fowler
Administrator
Trade Count: (1)
Hero Member
*****
Posts: 3451



View Profile WWW
« Reply #25 on: November 18, 2014, 03:44:52 PM »

That is his choice. When we started Rex was very interested in working with knife makers and sharing information.
He sent steel to makers to try, most did not even thank him or send him money for shipping. There are a lot of jerks out there.

Another man of science joined is, took a look at one internet forum and said "we were casting pearls before swine" he would help us but wanted no personal contact with the knife community.  At first Rex and I were intermediaries, now it is just me.

Were I to have to opportunity to go back and start over knowing the reception our thoughts would have on the knife makers and ..............I am not sure how I would operate.
« Last Edit: November 18, 2014, 04:28:08 PM by Ed Fowler » Logged

Ed Fowler High Performance Knives
http://edfowler.com/
Daniel Rohde (D-Vision)
Trade Count: (0)
Hero Member
*****
Posts: 1100



View Profile WWW
« Reply #26 on: November 18, 2014, 06:34:44 PM »

I have really been enjoying this discussion guys! Thanks
Logged

Consistent, Repeatable Performance is the goal
http://www.rohdeedge.com/
mreich
Member
Trade Count: (0)
Hero Member
***
Posts: 812


View Profile
« Reply #27 on: February 22, 2015, 05:27:26 PM »

Is the 1725*F soak to spheroidize the steel?

I thought I read that the high heat soak with a slow cooling (like leaving it in the oven) does that, but I ruined a whole batch of blades overdoing it. Pretty sure I held it at that high temp way too long. They were covered in deep spiderweb cracks. I've been very careful not to come close to repeating that.

It seems like spheroidizing is something you'd do to blades so they'd grind easier, but I don't think annealed 52100 is difficult to grind at all.

I know that bar stock is usually spheroidized, and you have to have high heat cycles to deal with it.

Would spheroidizing be effective to prepare the billet for forging? It doesn't seem like that should make any difference when the next step is soaking the billet 1hr per inch at a slightly cooler 1600*F to begin forging, and once you start forging, doesn't the spheroid phase evaporate?

Ed, why did the "other man of science" say you were casting pearls to swine? What didn't he like?

When you say you aren't sure how you'd operate now, do you mean it's just a PITA arguing about HT with other makers?



   
Logged
Ed Fowler
Administrator
Trade Count: (1)
Hero Member
*****
Posts: 3451



View Profile WWW
« Reply #28 on: February 22, 2015, 07:37:11 PM »

What the soak does is neutralize any differences in the steel due to thermal events. You are starting with each piece of steel from the same pour at the same gate. I do not know the technical stuff, just that it works.

The other man of science took the time to read one of the popular forums and noted all the flack we were taking and decided he did not want to play. Today I feel the same, the knife is a simple tool, it can be tested for quality performance in a laboratory no more sophisticated that the average knife makers shop.

For those who want to know why, there is plenty of evidence in the blade, all they have to do is dissect one and figure it out.

Rex and I decided at the start to learn what was happening and understand it to the level that we could explain it to the average 6th grader. I believe we have achieved that goal.

Those who chose to figure it out from looking at the final product will have fun. The metallurgist who made the 52100 we are working with did not recognize it as his when he saw a photomicrograph in the lab.  Even after shooting a chemistry and his own photomicrograph. All it did was aggravate Smiley him.

Rex and I could have sought copywrits or patents, but started with the desire to share. I am glad we did, but I would have never entered into any debates. I would discuss, but not debate or try to explain any more than we did. Many have fallen into the trap I did, I was not prepared and now understand the flack we took better. It is a fight many have fought before.

Kevin saw what happened, tested it and the paper he wrote was enough to grant him his Masters Degree from your school of mines. What more can we ask for??
Logged

Ed Fowler High Performance Knives
http://edfowler.com/
ChrisAnders
Newbie
Trade Count: (0)
Sr. Member
*
Posts: 193


View Profile
« Reply #29 on: February 22, 2015, 08:24:12 PM »

Is there a way to get a copy of Kevin's Master's thesis? 

Mreich, the 1725 F soak is high enough that no carbides will be present.  They are all dissolved at such temperatures.  If you did a high heat soak like 1700 or so and slow cooled in the oven over a long period of time, I can see why you'd have spiderweb cracks in your blades.  It wasn't all due to heat, but also due to the slow cool.  Slow cools like that in steels like 52100 (or any steel with more than about 0.8% carbon) can cause some nasty carbide networks that will surround the grains and allow a crack to run along what is basically an all carbide path.  I think I've mentioned here before that, if one wanted it, a steel could have a hardness down around 20 Rockwell C, and have an impact toughness rating less than a fully hardened blade.  You accidentally found out how to do that. 

Spheroidizing is something one does to steel to make it easier to machine, as in with files or milling machines or drilling or such.  It probably helps with grinding too, but you would have to grind a tremendous amount of steel and keep very good track of the time it takes and how many belts or wheels you use up to see the benefit of spheroidizing before grinding.  Along the same line, annealed 52100 will drill fine, but if you're making 200 holes a day, well, spheroidizing your steel first will save some time and wear on the bits. 
Logged
Pages: 1 [2] 3   Go Up
  Send this topic  |  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.21 | SMF © 2015, Simple Machines
TinyPortal v0.9.8 © Bloc
Valid XHTML 1.0! Valid CSS!