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The Newbies Arena Are you new to knife making? Here is all the help you will need. |
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#1
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Newbee looking for input on results of HT
http://www.knifenetwork.com/forum/album.php?albumid=525
I have three pictures in the album showing the bend, break, and grain from testing my first HT. I broke it on purpose without tempering first to see what would happen so I can learn from it. What I want to know is if this is the expected result for a blade broken after HT and any advice if I should do it differently. I appreciate any input. This is my first and I want to get the HT part right before I go on to finish a blade. Here are the particulars: Used 1080 and canola oil quench. Heated till non magnetic in a gas two brick forge. My oil was about 70 degrees. After it cooled a file skipped along the spine the same as on my Mora knife. I did not temper but went ahead and put the tip in the vice and bending from the end of handle had about a 45 degree bend before it snapped. But a lot of that was flexing in the handle area the back half of which had not reached HT temperature. If I had bent just the treated blade I don?t think it would have flexed so far. Any input would be appreciated. |
#2
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Good pictures. Next time you break on put some pieces of hard wood between your vise jaws so that the blade isn't bending across the sharp edge of the jaw.
Other than that, raise the temp of your oil a bit, about 90 - 100 F. You mentioned non-mag, be sure you're seeing non=mag on the way up, catch it when it first gets there, don't let it go past and then try to bring it back down. Once you have it put the blade back in the forge for a short time. Hard to say exactly how long as the mass of your blade and the temp in your forge are unknown but likely somewhere between 15 seconds and maybe a minute. You want the steel to be about 100 - 150 degrees beyond non-mag when you quench. Try that a few times varying the specifics and see if you can get a light grey color with very fine grain and not so much lumpiness. Should bend some and then break like glass so wear eye protection... |
#3
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I have been going through a lot of trouble trying to get my heat treat right. I am using 1084 and canola oil in a gas forge with a proper venturi burner(my first couple burners were pretty large torches and they just werent cutting it). It looks like you are experiencing similar issues to me.
Here is one that I did correctly. Look at the center of the two pieces as oil has stained the edges in this pic as I didnt take it immediately after I broke it. The blade should snap pretty clean when done correctly. https://drive.google.com/file/d/0Bxh...w?usp=drivesdk |
#4
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I think that your grain is a little on the course side but it can be difficult to tell some times when you get a ragged break like that. If what you were saying is true about the file skating across the edge but the blade bent to 45? then I would agree that you did have differential hardening but that would also be influenced by the make-up of the 1080. The 70? oil might be a factor too. It might seem counter intuitive but oil at that temperature cool more slowly than oil heated to around 120?-130? which could account for pearlite or at least a mixed structure in the spine.
Doug __________________ If you're not making mistakes then you're not trying hard enough |
#5
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Break a quality file and look at the grain. That is what you want your grain to look like. Find a worn out quality file. Just vise it and break the tip off of it.
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#6
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I'm FAR from expert and won't comment on the grain, but something Doug touched on, differential hardening. I would expect the blade to bend about 45? and break like that AFTER tempering. I would expect a quenched but not tempered blade to break before reaching any 45? bend and I would not expect the blade to stay bent as the one in the photo, that is again, unless it was tempered.
It looks to me like perhaps it didn't fully harden and that is probably because of the "cold" canola oil. As others have said, warmed canola actually cools faster than room temp oil. I quench with canola @ 120?. __________________ Find me on Facebook: https://www.facebook.com/gpopecustomknives/ Gloria In Excelsis Deo!! |
#7
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Yeh I would agree the grain is course, also IF its not tempered it should snap fairly quick it shouldn't do much bending. AFTER you get the grain right and it snaps clean then go and make a blade temper test and break, once its tempered it should bend like that not before.....still a lil to soft.........just a tip, so you don't waste a ton of steel. Make coupons first basicly a rectangle piece of steel, on each long side of the coupon you put a V notch about a 1/4in deep.....heat treat this coupon just as you would a knife when you break it align those V nothes with the top of the vise jaws. The notch just gives it a weak point to break. this way with the same amount of steel that you could make 3 or 4 coupons (of corse depending how big your knives are) that way you don't waste a bunch of steel. ONCE you get the grain good and fine.....and have it snap without bending (if it UN tempered) then you repeate that heat treat on a new test knife....trust me it saves a lot of steel
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#8
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A couple things I noticed (It's REALLY difficult to tell how well your grain structure is in photos).
Doug mentioned a few of these already... If all you did was take it TO non magnetic...that was not hot enough. Non magnetic is ~1414?F, and 1080/1084 should be taken to 1500?F, and then with an even heat (soak a minute or two). The edge may be 1500 but the spine may not, in other words. 1080/1084 doesn't need a soak, but just make sure temp is equalized through the piece. 70? canola (assuming ?F here) is pretty cold for canola. Should be ~130?F. The 1080 steel needs a somewhat fast quench oil, and warming canola to the 130?F mark is what you're after. The grain, to me, looks OK. Notice the grain right at the edge, and the top corner, where you have a nice, clean fracture. Looks like a solid gray, non textured surface. Excellent. The area that looks more "coarse" MAY (or may not...hard to tell online pics) be just the bent steel that did not fracture well, and always will give a coarser look than the grain actually is. |
#9
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That's a great idea, thanks! I broke one and it looks like a perfect grain. now I have a sample to compare to.
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#10
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I want to thank you all for taking the time to respond and share your experience with me. These are some great tips. Lots of experimenting to do now!
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Tags |
1084, advice, back, bee, blade, brick, burner, cold, degrees, edge, file, finish, forge, handle, heat, heat treat, knife, mora, quenched, sharp, steel, tips, vise, wood |
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