Very poor test results HELP! Test two cool!!!

[prarieboy]

These 4 blades are made of used plow steel about 3/32" thick. I anneal in our charcoal babeque Double use for the charcoal makes things taste better!
.  I have a very primative propane forge set up no way to truely control or soak  at a certain temp.The only actual forge pounding I do is to thin the edges to save My fileing time.
 these were all brought to non magnetic and cooled somewhat (probably 10 minutes on 100 degree day)  
3 times before goin to nonmagnetic then quenched in a thin synthetic oil that is being reused.(recycled compressor oil). then tempered in my toaster
oven set at 400 deg. for 2 two hour cycles.
 The knives I have made like this hold an edge very well. The knife that I have ask for help with sheath ideas I have chpped completely through a 2x4 twice
then cut a lot of the leather for that sheath and watched a friend cut a calius off his hand with it before resharping! But they apparenly are not crowbars!
I am  poorfolk and can't afford a lot of changes just need to learn what I have.
The grain looks the same in all 4 breaks. I think they all broke at about 15 degrees of bend. Thanks for any and all advice! C-Ya Bob
   
   
   
   
Results Much better!!!! edge quenched let cool completely during normalizing steps and used veg oil also checked for non mag a lot more cautiously. I also Think that I learned it is good that the blades will not catastrophicly fail but it is relly more about flexabilty than failure. The first time I Bent it went to about 45 degrees and released it almost returned to straight!!    LOOK MA NO CRACKS
 Thanks again Folks C-Y-All Bob
   
   

[LONGBOWKID]

Bob, try vegetable oil. Its cheap and what I use.

Do everything like before, but after your tempering, put the edge in a pan of water, and heat the spine of the blade with a torch until it turns blue. That should soften the spine and you should be able to pass your test. Youre also testing fairly short blades, which doesnt help either, they dont bend nearly as easily as a longer blade, for obvious reasons.

Someone will be along to better explain what to do, and probably give better advice than I.
Kid

[Lin Rhea]

Bob,
      Are you full quenching the blades? Sticking them point down all the way into the oil?
    Have you determined at all what plow steel is? How much Carbon is in it? This not as important as the first question. It's obvious that it got hard. Sometimes the alloys may play a part. I dont think plow steel has many alloys, so that may not be as important.

     Lets stop there for now. Lin

[prarieboy]

Thanks guys  Lin I am Quenching point down and stopping just above the blade trying to leave the tang soft. as far as knowing what steel all i have is that junk yard steel on the web says plow steel is probably 1080. thanks again

[Lin Rhea]

I was going to say 1070, which is close to what this chart says. Of course, I dont know that this chart is accurate, but I bet it's close. It's probably a simple steel and can be figured out pretty quick and get this problem remedied. Lin

[Lin Rhea]

Bob, By quenching point down and hardening the whole blade(except for the tang), your not alowing the blade to have any softer areas to be able to bend.
  If you want to make a test blade and have it differentially heat treated, you have to either edge quench and thereby only harden the edge, leaving the spine relative soft and bendable or harden the whole blade and then draw back the spine with a torch as the Kid said to do. You will basically have the same thing, as far as a test blade is concerned. You can achieve it either way.
   You are just using the oven to draw back the whole blade, which is not what I'd call differential heat treating. In other words, the way your doing it, the spine will read about the same rockwell as the cutting edge. I would expext it to break done this way. I think you are making a servicable blade as is, but for a test blade there needs to be an additional step. That is to draw the spine down with a torch to soften it some. Then it will bend more and if it cracks, it most likely will just be the cutting edge. That's actually not such a bad thing. Lin

[prarieboy]

Thanks again Kid and Lin I am noomalizing another teser now and will do an edge quench then temper and test in the mornin will let ya know one way or the other if i'm learnin or not LOL! Big ol bite humble pie for Me today !!!      

[Lin Rhea]

That's better. Your right. I'd rather have flexability than bendability. But you are in control of that now. Lin

[LONGBOWKID]

Looking better Bob. Thats exactly how I quenched your blade. If you get it in the light just so, you can see the quench line. Have you done any cutting with it?

Kid

[prarieboy]

It seemed very durable Kid

[Steve Nuckels]

Good post!    Thanks!  Good stuff Bob!  

I have a stock removal project to finish then I will start my forged bladed knives, can't wait!

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IN GOD WE TRUST