Dots in the Steel

Greg Covington

Greg Covington

Joined
Oct 28, 1999
Messages
1,563
I just finished a small skinner/utility knife made of 1084 steel. I edged quenched (3 times) and tempered at 375F for 3 cycles.

I wanted to etch the blade in a ferric chloride solution to show the heat treat.

The etch revealed the hardening/temper line but there are dots throughout the blade surface.

I remember Ed Fowler taking about these dots but he never said what they were....he just said they occassionally show up to make hime smile. Any idea what they are?

The knife cuts great and flexes like a spring.
 
I always thought they were the result of scaling. They ALWAYS show up on my stuff but they are shallow. I regrind after heat treating to skim off the decarbed steel and they go away. (Most of the time)
 
Hmmm...that is what I was guessing but it was odd since I had the blade down to a 500 grit finish before the etch.
 
Do these circles show up in the scale after you heat treat? I've had that to happen, and they are a lot harder to sand off than the rest of the scale. (I'm still hand sanding after the heat treat.)

I've noticed this problem if I heat the blade too long, or if my quench is too hot from a previous quench or preheating.

-chris
 
I think you are over heating a bit before the quench I also dont think you need to triple quench and triple temper 1084. It is needed with 52100 though. Ive had good results with one quench and double temper with 1084. Temper to 375 untill light straw color.
 
Thanks Bruce....

I will give a single quench and double temper on my next 1084 blade. So far the 3X quench and 3X temper has been great on 1084.

I have been tempering at 375-380F and the blades turn a nice light straw color.

As far as the quench heat....I have been quenching as soon as it hits non-magnetic so I am pretty sure I am okay there. The dots really don't appear to be grain structure, but more like scaling.

Here is the knife....the link from Geocities won't work here but type this into you browser's address bar if you would like to see it:

www.geocities.com/bladernnr66/small.jpg
 
Ok, about a year or more ago I had some dots show up on one of my blades....I didn't have a clue how they got there, but they were real, and they kinda took the eyes off the rest of the blade when you looked at it.

Now a while ago I saw Ed Fowler post a photo here on Blade Forum that he said was about the best blade he had ever done.

The trouble is that when I looked at the photo, all I saw was the very same type dots that were on that one blade of mine. I asked everyone on that topic about the "dots" and Mr Fowler seemed to remember some other guy, (Perhaps a Japanese sword collector?) said that the dots represent a "refined Grain structure"......(I didn't have a clue what that meant)...

BUT THIS MORNING.... when I ran to the living room to see what Santa had left me for being very good all year, I found a Japanese Sword making book called : THE CRAFT OF THE JAPANESE SWORD.

Guess what? I read about our "dots" on page 92 !!!!!!

The dots in the photo on page 92 are the very same dots that were on the Fowler blade, as well as on my blade...(well I think they are, they sure look like it to me)

The dots are well known to Japanese smiths and turn up so many times that they were even given their own name. They are called "nie" by the Japanese smiths

I will now quote what it says in the book about them:

"Nie, for example, appears as discrete and visible dots; it is produced when grains of austenite grow sufficiently large."

There is also a bit more in the text about the dots that lead me to believe that they show up when the blade was really really heated to very high temperatures. Such dots on Katana show that area is "brittle and prone to damage."
 
Greg, I've had dots show up after etching on a blade or 2 but it was from the etchant, itself. When I placed the blades in the etchant little bubbles would appear and not let the etchant get to the steel, therefore causing little dots. What I do now is when I place a blade in the etchant, I run a soft tooth brush down the sides to remove any bubbles that might have formed when placing the blade in. Hope this will help.

Bill
 
Bill this is exactly what an artist does when he's making an etching. But I think it can be more than one thing. If the material gets brittle that's a perfect sign of overheating. Decarb may be a cause and having segregation like alloy banding could do it too.
 
B . Buxton...yes,,,,thats true,,,and I never thought of that, so thanks for the heads-up on the etch situation...

However the dots on my blade ,(and if I remember right, on the Ed Fowler blade) were just along the cutting area of the blade. I remember that my dots stayed about 1/4 or so up the sides, but were not found in the un-hard parts of the blade.

Now last night I went over the dots question again from that book I got yesterday and read a bit more so I understand what they are talking about with the dots.

The dots are what the Japanese cal Nie and are one of three different ways the japanese smith uses to produce the hamon line.

On page 51 of the book it talks about modent smiths experimenting with use of the Nie "dots" ....

In my own case, they turned up on a blade that I was experimenting with. I was useing a whole bunch of quenches on the blade. While forging the tang I cold-quenched the blade a few times. Then I did 3 very fast Heat-treatment quenches and then ran the blade after the 3rd quench into the hot oven....I was attempting to learn if it mattered as to the number of quenches you used????,,,,turns out that this was the only time I ended up with the "dots" so i would say that, :"Yes, it mattered..."..LOL

Im not a man of science, so I can only guess what to take from the quench experiment I did that ended with a "dot knife"...but I think, (I guess?) that if I was attempting to push the steel the the upper limit of what it can do, then this limit I close in on is in fact - brittleness and prone to damage."

I aim to make a knife that is "dead soft" along the spine, yet super hard along the cutting edge.,,,My dream blade would have a spine that is so soft that it cant really ever be broken, yet have a cutting area that is so hard that the steel could not test out with a higher RC-hardness without becoming so brittle that it snaps during the testing....

The dots on my blade would seem to be the sign that "Thats about it"...thats about as far as that steel can go before you start to hurt the blade so much you are going downhill...

(Well,,,it's just my take on the meaning of the dots anyway, I could be just trying to put the best "spin" on them too ...LOL).
 
The blade that was in the photo with the dots was an exceptionally high performance blade. Cut, tough (edge flex) and ease of sharpening were all present. We did not have access to a lab at the time and decided to let her survive as a knife, she became one of the experimental blades that got finished.
We had a lot of thoughts about the dots, chromium carbide aggregates, seemed to be the best guess. A full understanding would have requuired a lot of lab work that we can't afford at this time.

The dots can be achieved many ways, I once got them to show up on a rail road spike blade. I do not believe they carried the same message that came from the knife in the photograph.

At this time we believe the dots were a result of the nature of the steel before we started forging. Rex decided and I agree that we need to learn to duplicate the dots with steel that starts from a known starting point. I devoted two months of experimenting and found out other things, but have not reproduced the dots in the same distribution as of yet. We will or hope to have access to a Lab in the next couple of years, then we will or may know more. In the mean time We are exploring specific variables and their effect on specific aspects of performance.

The more experimenting and reporting of results that we do as blade smiths the greater our knowledge and I sincerely thank those of you who have contributed to the thoughts in this thread.
 
I will try to set up a site where I can post a photo of the blade in the book,,,,this way you can look and see if the dots along the cutting area of the Japanese Katana are anything like the dots we have run into in the past...
 
I just ordered the book through Amazon, should have it in a week or so. Thanks for pointing out its existence, I have not seen it or knew of its existence. Looking forward to reading and seeing what they have to say.
 
Page 92

http://daqotah.tripod.com/

I know my computer scanner is not all that sharp,,,,but you can get the idea that the dots on the japanese blade are the same type as what was on one of mine that I did a ton of heat-treatment quenches on...

Japanese Katana steel is a folded mix of many steels, so it is not the same as my pure 52100,,,,and so I would expect the dots to be a bit more mixed around than my blade, but still,,,the dots on the katana seem to stay close to the hard areas of the blade
 
Sorry I am a bit late on this thread. Been sick so I am catching up on my reading.

Greg,
"Dots" is kind of vague, you know. I have had guys call me about lots of dots and patterns after etching. It's always tough without a really detailed pic.

It could be the whole temp a bit high deal or it could be your etch...
Hard to know...really ..if she cuts good and works for you...do it again...same everything ...see if it happens again.

As for the "Nie" theory...

I had the priviledge of holding that particular Fowler blade at Ed's shop in Riverton. The "dots" on that blade were large, and pronounced. Even though they appeared to "rise" off the surface of the steel, they did not. I have seen a few Asian blades with "rough" sections of "loud" "nie"...but nothing like this.

Even taking into account the different finishing styles...it was different.

Just my .02

Shane
 
shane.....

well,,,perhaps,,,the idea that the dots on one of my blades are somehow connected to the Japanese Nie is just my guess....

I look at the photos in my Japanese sword making book on page 92 and the dots on the Katana sword sure look like the same dots on the knife I made....same position, same "look" to them...

And the moment I saw the dots on the one Fowler blade that was posted here last year, well, they also "sure looked" like the dots on my knife...

So thats why I would be very interested in what Ed Fowler thinks after he has had a chance to look at the same photos Im looking at...

Perhaps this means nothing?..I dont know, but it would be cool to learn that the blade that Ed Fowler believes was amoung his best, also shows a tell-tale sign that it has something in common with the very best katanas from Old-school smiths in Japan....
 
Hey DaQotah,

No worries...wasn't trying to say your dots aren't the same as the one's in your book....or for that matter Ed's dots...

Just offering a thought...since a lot of guys have seen the pics...but haven't messed around with the knife.

It may be some kind of "like phenomenon". I don't know.

Just trying to help.

Shane
 
I purchased the book through Amazon, just got it. The pattern you see is different than the one I found in my blade. To try to explain the dots,I saw and had developed, they were like speckles of diamond dust. Not the cloud type in the phtoto.

The first time I saw the speckles in a blade, they were in a sword that a collector had in his display case. After some careful thought he allowed me to look them over closely. The best analogy I could come up with, they looked like diamond dust in the steel. He was highly informed as to their nature in the history of the Japanese sword and had picked this one on the basis of a recomendation from another collector and friend who lived in Japan, living and breathing their work. The sword he owned was valued in the five figure range.

I now believe that I know how to produce them at will, but thanks to the wreck last year now know how to take the steel further. It will be about 16 months until we have a lab. to explain what we have, but judging by performance, (cut, strong, flex) I am very pleased with our results.

I thank you for sharing and asking the questions you do, the insight into the events, and putting them into perspective, just came clear to me while thinking about this stuff.
Happy New Year!
 
cool....I cant wait for your next book!

Ed , just to make sure we are looking at the very same photo...

The dots that sure look like MY dots are on the sword on the bottom of page 92, lower right-hand side of the sword, the word "nie" indicating with two little arrows a collection of dots, a quarter to half-way up the side of the blade.

This is not to be confused with the misty and indistinct "nioi" which appears to the left of the same sword.

The "nioi" sure does resemble misty clouds or those little drifts of snow that run across the freeway, but the individual dots of "nie" sure do appear to be the dots that I encountered on one of my blades.

On page 31 of that same book THE CRAFT OF THE JAPANESE SWORD, the paragraph that starts, "Using precisely controlled..." sure does sound familiar to me with the other books I have been reading as I have pursued my own development of a high-performance blade.

"Smiths (from Japan) are also experimenting a great deal more with their forging methods... (page 51, THE CRAFT OF THE JAPANESE SWORD).
 
You guys are talking about the very same dots I have been experienceing. I was told mine were from overheating problems. Since then I have managed to minimise if not eliminate those from my finished product. I do think that the blades that I have where these dots are present hold a very nice edge.
Here is a cool pic of some cloud formations I was able to get. This blade has some of those dots but very little. You can make some out from this picture.
Interesting thread!

What can you tell by the etch?
doublegrind.jpg
 
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