I seek advice on 52100 Heat-treatment

yes...one day..a power hammer..ahh yes, that would be nice.


But the darn things take a pile of money.
I did bid on a few this last year on Ebay, but my limit was well short of what other people are ready to spend.

Still, Im very lucky to have a wife that enjoys her chance to help out in my shop. She had a few brothers that worked with steel so she understood right away what to do and how to hold the hot steel so I could hit it flat.

But yes. if Im going to start to use my bucket of ball bearings to make knives with, I better keep an eye out for a power hammer one day.
 
If it's moving that slow, at that heat, they may not be 52100. Some bearings are made from stainless or high alloy tool steels, both of which would move slower.
 
Yes, one other steel that I have seen used for bearings is 50100B, close to 52100, but different enough to throw a wrench into the works. a little less chrome, some vanadium. It is also more sluggish under the hammer, but I like what a little vanadium can do for a blade. Because of the variety of steels used in bearings, if you want to forge them, I would suggest going to a place that makes bearings, and asking for the cut-offs (fresh steel which you can usually get at scrap prices), and asking for the mill specs for the steel used in that run. then you will know what you are working with.
Ken
 
Alan... I'm not a knifemaker, but this is an interesting and very informative post. Best of luck finding a power hammer that you can use in the near future. Keep up the work and it will pay off.
 
Making knives is just a little hobby of mine. Just something to keep my butt out of the bars in the long winters here.

I read here that Ed Fowler used ball bearings when he started out and so I have always wanted to try my luck with a bearing.

But I cant tell you how different a bearing was to forge compared to the normal john deere load shafts I have used in the past.
In the video of my wife and I forging the bearing http://www.youtube.com/watch?v=TzJ-91nUhPA I am banging that darn bearing as hard as I can. I didn't hold anything back.

In the next attempts that came after we filmed ourselves I bumped up the heat and things went better.
Not shown in the video are some problems I had as I got about ½ way done with the hardest forging of the bearing.
When I had finished the tang, and then started to forge the tip last, I ran into one small problem. I lost track of where the 52100 steel left off and where the mild steel of the shaft I had welded to the ball bearing, began.

I had done a very good job of welding the shaft to the bearing, and when I started to decide the tip's position I found I was unsure where to stop.

I ended up cutting the bearing steel free of the mild-steel shaft, and then cutting more and more steel off the end of the tip to make sure I had no chance of mixing the mild steel with the bearing steel.

This all leads me to one more question:, Do you real knife makers find that you are always facing a problem with making a knife you didnt see before, and having struggle a way around the problem?




Anyway, Live and learn?.
 
Problems are actually opportunities, smile and welcome them to lead you to greatness!
I was going to quit making knives, took 5 months off and read many varied books, learned a great deal. found out that US steel worked and patented multiple quench years ago.

Went back to making knives and WOW, stuff that was very laborus became fun, new ways to acomplish tough tasks awaitied, rebuild my 100 and one 50 pound little giants, they run like clocks.

Enjoy those problems.
 
Ed Fowler said:
... found out that US steel worked and patented multiple quench years ago...
Click to expand...

Ed, please believe me that I am entirely sincere when I say I have no intentions of making any waves here, since you have many more years of experience working with 52100, I wish to leave this thread to you in helping out the gentlemen with their questions. For some time I have kept my eyes pealed for any information on industry’s use of multiple quenching in order to get a better understanding of it through that perspective, and this is pretty big news on this topic. So I only write this one post to make a sincere and humble request for a point in the right direction of any literature or information on US Steels work in this area as I would find it immensely fascinating. Believe me I know how hard specific articles can be to find so even patent numbers would be invaluable in tracking it down myself. I would be greatly appreciative if you would be willing to share any sources for this, even if for a well deserved “I told you so”. ;)
 
Rats, you beat me to it, Kevin.

That was one of my questions, too... but I also wanted to know what books you found inspiring, Mr. Fowler?
 
Kevin: I was using multiple quench before I read about it. The first reference I found is noted below in the book from the 30's. I came across the process purely by accident. It is like I have said many times, there is nothing new, we just discover it again. If I was not obcessed with performance at the time I would have never known about the benefits. Later when I found the event documented, it caught my eye, otherwise I would have read over it.

There is a reference to it in the 10th edition of "The Making Shaping and Treating of Steel" by USS United States Steel. Page 1264. I also read about it in a book that was written in the 30's where they had used what I call multiple quench on some 5160. In a footnote they stated "This was the finest grain in this steel we have ever noted." Strangely no one tried any performance tests on it.

New Holland later sold some sycle sections that had "been through the fire twice". I bought several hundred of them, but did not keep track of how they compared to the other sections because I was pretty busy farming at the time. They quit advertising them, I heard and only by specualtion on my part feel it could be due to an infringment on what U S Steel owned. Who Knows?

Another great book that continues to educate me and reinforce many events that I have noted is "The Prevention of Fatigue of Metals" by the Battelle Memorial Institute. Written in 1941 for the US Navy Air Command they were trying to make airplane parts that would not kill pilots when they failed. There is some dynamite information in this book and it contains refferences to information they quote. Some back in to the 1920's some I have been able to read and - wow, others have ceased to exist, at least according to my library. I believe this was truly a golden age in the science of metals. They note qualities and variables in steel that manifest themselves later in the life of the steel that there is no way to evaluate them to this day, other than performance. They shared openly (I think). I wish I was fluent in German, this seems to be our greatest resource.

I noted some events, thought I was nuts until I found refference to them in this book. Now I know that others have witnessed the events and in talking to Rex there is no method in science to tell us what happened other than noting that something happened and we know it did due to differences in performance.

For example:
The knife tested in our new DVD did not make over 32 cuts the first time we tested it for cut, Eldon, Butch and I took turns sharpening and cutting. Months later when Rex visited and we again tested the blade it made 200. Something changed over time. First thought is the old explanatioin everyone reading this has thought of, transformation of retained austeniteinto martensite. But this is not the case, there was no retained austenite in the blade when Rex did his postmortum on the blade after testing. It was the Battelle book that provided the information that someting else could have happened. this gives me the courage to metnion it here, maybe one of you reading it will find a similar event and the technology will be available to see what happened. Those of you who have purchased the DVD and watched it will agree that the likelyhood of untempered martensite is not probable.

Rex was doing some Johmney tests on multiple quench 52100 steel that he is going to write up that offeres even more information.

We now know why the martensite cone forms inside the steel, the variables that influence strength in reference to the cone and why double edge blades only edge hardened like to twist.

We have answered many questions, have twice as many to explore and a new goal that will put it all together, complex complimentary geometry in reference to thermal cycles and differential hardness (in response to your question I just coined that concept) that allows for the contributiion of all the variables we have been working with at a new level.

I am sorry that I cannot come up with more complete information on US steel's patten, or the development of their process, but this is the first one to come to hand. From what I remember they did their work in the 1960's. I have a stack of books stored in a very cold place at this time and all my notes are in the books where I can find them, I hope. I was not compiling notes for future debates, but ideas on performance. I believe there was some mention in one of the "Bearing Steel" books through ASTM. I will try to find more if you wish.

Rex used to ship me huge boxes filled with trade magazines suggesting there was something of interest to me on one of the issues. I would read them, not find much of significance and he would state 'I must have sent you the wrong pile', and a week or so later here would come another box. That is how Rex Educated me. Maybe I still have some boxes of them I could sent to you. If you think I am in left field much of the time, you should read some of the trade journals.

I have found that much of the information that is of vlaue to knife makers comes to us in the form of footnotes, and digging back through references to other footnotes. You won't learn a lot, but it will provide confidence that others have noted and wondered about the same phenomena.

I did not mean to write a book, but finding your question at this time of day I was inspired.
 
Ed, You are right. You can find a wealth of information from old books, technical papers, articles, magazines, etc. When I first read this I thought that precipitation hardening might be occurring. But then I looked up a tech data sheet (http://www.suppliersonline.com/propertypages/52100.asp) and found that aging techiques are not applicable to thia steel. Precipitation hardening occurs when one of the constuteunts is precipitated out, over time, from a supersaturated solution. There are precipitation hardening steels but 52100 is not one of them. It is realy designed for good hardenability and toughness to handle the sub surface stresses that occur in ball bearings. However, it will work harden. So it will get stronger or harder with work. It is possible that there may have been an improvement via the blunting and sharpening cycle that has been observed in some of the knife reviews on the web.

The tech data sheets for steel can be a bit sterile and more useful info can be gained by reading old books or from experienced people. Data sheets give no clue of effective techniques. Sometimes they will refer to techniques such as martempering but not always. I like the way that forums such as this one enable the sharing of info such as has happened in this thread. I am starting to ramble so I will cut this short.

MDG (retired Mech Engineer from OZ)
 
Well, the guard is on, the Micarta handle is on, and I have sanded on the handle down to the point where Im very close to where I want to stop and buff it out so that it all looks cool.

However now I have been thinking that I would like to know about one thing that I did that Im not sure of right now :

I soldered on the brass guard yesterday before I did the Micarta.
When I soldered I only put the heat of the O/A torch from underneath the guard.
I used low-temp solder and it went very fast, however now there are what appear to be little holes in the racaso area ahead of the guard.

I did a little light sanding of the ricaso and the little pin-point holes seem to have been caused my the soldering.

I did not think I over-heated the steel, so what caused such little pinpoint holes there?

Over-heating?
 
I doubt the holes got in the steel through the silver soldering operation, unless you had the blade heated to a yellow heat and above, I doubt you did this. Probably they occured during the forging process or may have been there when you got the steel, just not visable. It is probably too late to get rid of them now, just relax and enjoy them as a part of your first blade.

I usually forge oversize, then grind down to steel that has not been subject to all the trauma that the survace may know during the forging process. 1/32 of an inch is plenty enough - usually for this kind of problem, unless they were in the steel before you got it. This is why I feel so fortunate having tons of the same pour available, it has provided a consistent reliable source of material that allows more meaningful experiments.

Don't dispair, you have a lot of time left to work this kind of stuff out. I hope.
 
MDG: The germans were so far ahead of the rest of the steel industry up to the time of WW II that we weren't even in the same race. In reading the Battelle book I was pleasently suprised how much information Krupp let be known to the outside world. I believe that after the war to end all wars security laxed for a time and we had a chance to learn. I wonder what information remains in those old references?
 
If I did over-heat the blade, would the solder have worked as well as it seemed to have for me?

I heated the lower guard brass and the tang with the O/A torch . I had set the O/A torch on a lower burn.

The moment I saw the solder start to flow on one side, I heated both sides one more time than dropped the torch .

Lets say I did heat too much, IF I did then would an acid-etch show me this now?

Can you etch a blade after the brass guard and Micarta handle are on, and would this not only show me where the blade was made hard in the quench, but also where I might have over-heated the blade at the guard?
 
What type of flux did you use to solder on the guard? Maybe that is what caused the pitting.
 
I use one of them little bottles of stay-brite flux.
the solder is from radio Shack....

QUESTION:....Could any type of flux cause harm to steel in any manner?
 
What I meant to communicate was that you could not have over heated the blade enough to cause the pits during the silver soldering.

I always etch the blade , immediately after heat treating, before doing any more work on it. This way the etch will reveal any errors in heat treat or forging and I won't waste time finishing a blade that is not up to my quality control standards. Etching every blade will teach you a lot about your methods, you can read what you have done for it is recorded in the steel, revealed by the etch.

You can etch a blade at any time you chose to. You can prevent the etch from attacking the guard by painting the guard with finger nail polish.
 
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