Author Topic: 1095 hardened and tempered (Read 1183 times)

jackie · « **on:** February 19, 2011, 07:30:00 PM »

after hardening and tempering 1095 3/16 steel i put in a vice and attempted to break it. it moved about 20 degrees and then bang it broke is that about right for a finished knife. i thought i read where an abs? bladesmiths test said the knife bent 45 degrees and then went back to straight. just wondering if my knives were alright. they do just fine on the brass rod test. thank you jackie

Lin Rhea · « **Reply #1 on:** February 19, 2011, 09:15:00 PM »

Jackie, you have to give a little bit more info, for me at least, to know. Exactly how did you harden and temper the blade?

A full quenched blade that has not been drawn back on the spine could act similar to yours, but the ABS bladesmiths are taught how to differentially harden and draw back to be in control of the blade and make it act in different ways.

jackie · « **Reply #2 on:** February 19, 2011, 09:36:00 PM »

i took a 3/16 1095 about 6inches long and heated to 1500 degees then guenched it in parkers oil then heated it for two hours at 400 degrees then let it cool and then placed it in a vice to see how far it would bend before breaking. that is the way i make knives and i was just wondering if a knife that is about right would snap or bend. thank you jackie

OconeeDan · « **Reply #3 on:** February 19, 2011, 10:27:00 PM »

I would imagine that the short 6" length contributed to the breakage. I know that it is better to have 2 or 3 temper cycles, compared to one. Dan

Lin Rhea · « **Reply #4 on:** February 20, 2011, 07:46:00 AM »

Jackie, I'll have to assume that you are full quenching the blade, as opposed to edge quench. I am not suprised that the blade broke pretty soon, not because it's a bad blade or bad steel, but because you did not take the necessary steps to "set it up" to bend or flex 90 degrees in the first place. Unless you know what the steel's limits are and know what quench or quenching oil to use or how to differentially draw the spine back, taper the blade, etc., it wont do you any good to perform the bend/flex test.

The ABS school and class teaches how to get all the necessary elements wrapped up in the same blade.

When you broke the blade, what does the grain look like? Can you take some pictures of the end grain and post in this thread? Be fore you go any farther this question needs to be addressed.

jackie · « **Reply #5 on:** February 20, 2011, 06:43:00 PM »

i tried to take a picture put wouldn't show up. the end were it broke looks like very very tiny grains of sand. i guess my question is if i harden the entire blade and temper for two hours. would the blade breaking be normal and should i be more comcered about grain growth for proper hardening. what would to much grain growth look like.was just wondering if i can test my blades for better quality through this test thanks again jackie

Lin Rhea · « **Reply #6 on:** February 20, 2011, 07:01:00 PM »

Jackie, All other factors being equal, a blade whose grain has been reduced will out perform and out flex one whose grain is not reduced. These qualities equal a much better blade.

A blade will harden either way, but only one (reduced grain) will be properly set up to reach the steels full potential. Two knives, side by side, may look good, but one might not be a tough performer. Thermocycling is one step that prepares the blade by reducing the grain structure. After that is done and the blade is hardened and properly drawn back, it will be tougher. Tougher means it will sustain more abuse in just about every way. Any time a blade is broken it's an opportunity to learn something. You look at things like the grain size and consider things like the angle at which it broke, etc. All this gives you a correlation between behavior and appearance. Actually it's about the only visible evidence of a steels condition on the inside.

Take a look at these two chunks of 1084 steel. One has had the grain reduced (thermocycled), the other was just heated once and quenched.

jackie · « **Reply #7 on:** February 20, 2011, 07:19:00 PM »

mine looks like the bottom piece of metal. it broke at a right angle. mine has what i would call a few squiggly lines. like it broke there last. thank s jackie.

Lin Rhea · « **Reply #8 on:** February 20, 2011, 08:19:00 PM »

Well, that's good. Now we've established that your grain is reduced sufficiently to contribute to it making a tough blade. Your blade as it was before you broke it would probably be a servicable blade that would last several lifetimes....unless someone placed it in a similar situation as flexing in the vice. That's not likely, but the ABS is teaching us how to differentially heat treat to have a sufficiently hard edge while the spine remains springy or at least soft.

Personally, I like my using blades to be a little on the stiff side. It's less likely to bend and take set. Believe it or not, I also think it cuts better.

DANA HOLMAN · « **Reply #9 on:** February 20, 2011, 08:50:00 PM »

Lin,
Then you draw back your blade in the oven, let's say 2-2 hr. Cycles, do you draw the spine back again with a torch.
I have not been drawing back the spine just in the oven, is this wrong?
Thanks
Dana

Lin Rhea · « **Reply #10 on:** February 20, 2011, 09:03:00 PM »

Dana,
Again, are you full quenching or edge quenching? If full quenching, you either have to take great care not to harden the tang just behind the ricasso or you have to torch it a little to toughen it up a little and to make it where you can file the shoulders for the guard.

It's not a matter of right and wrong, but I know what you're asking. If I full quench, I will draw the spine with a torch to make the blade less brittle.

DANA HOLMAN · « **Reply #11 on:** February 20, 2011, 10:07:00 PM »

Lin
Most of the time I full quench, but I do not put the tang in and I normaly file the shoulders first before heat treating and tempering, I thought that was how it was done.
Thanks
Dana

Lin Rhea · « **Reply #12 on:** February 21, 2011, 06:44:00 AM »

That is ok Dana as long as you make sure not to harden the ricasso tang transition. I saw a 10 inch competition knife's blade break off in competition because this area was hardened and not drawn back. One way I make sure this dont happen is I file my shoulders after the heat treat. If the file has a hard time cutting, I put the blade down in water and heat the ricasso and tang with a torch, lightly till it's blue grey. Dont get it red, some steels air harden.

Bobby Urban · « **Reply #13 on:** February 21, 2011, 02:29:00 PM »

Lin is thermocycled and normalized the same thing? Do you mean taking the steel to critical temp(non-magnetic) and letting are cool until black a couple times prior to heat and quench? Just trying to understand teminology and make better blades. Thanks

Bob Urban

Lin Rhea · « **Reply #14 on:** February 21, 2011, 03:16:00 PM »

Bobby,
Normalizing is to remove stress and is just a matter of bringing up to about non magnetic and letting it cool. But, it does not specifically address the grain structure issue. Theromcycling does that.

To thermocycle, you bring it up above critical by maybe 100 degrees or even 200 degrees, then let it cool below a certain temperature (600-700 degrees), then back up to critical, then cool to the same designated range, then back up to just below critical, then cool to black. Each successive heat is lower and pulls the grain down to a point it looks like grey velvet if it was immediately hardened and broken. It will stay that way for your quenching heat as long as you dont go above critical by more than 50 degrees or so.

So, to add to this, theromocycling can reduce stress in the blade similar to normalizing, but normalizing dont necessarily reduce the grain as much as a controlled thermocycle.

tippit · « **Reply #15 on:** February 21, 2011, 04:41:00 PM »

Lin, What are your opinions on edge quench, horizonal entire blade quench, and vertical entire blade quench? Any pros or cons with these? Jeff

Bobby Urban · « **Reply #16 on:** February 21, 2011, 05:03:00 PM »

thanks Lin - very helpful. If you have a moment please take a look at my latest post and questions about heat treat on a longish thin blade. I PM with Mr. Anderson and tried to send you the same PM but your mail box is full. Probably a symptom of being one of the "experts" here - I am sure a lot of hacks like me bombard you with questions. You have no idea how much help you have already provided me vicariously on this site - Again, Thank you
Bob Urban

Steve Nuckels · « **Reply #17 on:** February 21, 2011, 09:48:00 PM »

Very interesting thread, I'm listening! An have similar questions!

Steve
-------
Potomac Forge

jackie · « **Reply #18 on:** February 22, 2011, 10:50:00 PM »

would like to thank Lin Rhea for his very informitive metal info thank you very much jackie

caleb0100 · « **Reply #19 on:** February 23, 2011, 12:16:00 AM »

All this info is very interesting, but it's making me wish I had more than just a brake drum set up.

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Author Topic: 1095 hardened and tempered (Read 1183 times)

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