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Heat Treating and Metallurgy Discussion of heat treatment and metallurgy in knife making. |
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#1
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Ht issue
I have a question about file teasting after i quench, if i lightly pass the file on an edge i kinda skates off but if i really bear down and saw away i can bite into the steel is this normal
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#2
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Not tempered? Then no, the file should not bite into a just quenched blade. What is your steel and what are you using to do the HT? A forge or an oven?
Also how long did it take from the heat to the quench? If you take more than a couple of seconds it may cool too much before quench. I never took longer than 3 seconds from the forge to the quench and usually less. If you're using a forge you also may not have reached the proper temperature or left the blade in long enough. So some more information would be helpful. |
#3
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Sound like you didn't harden completely. Could be caused by a couple of things, either not getting the steel hot enough to start with or not cooling it fast enough. You didn't mention what type of steel you're using, so I cant give you certain advise, but the best thing you can do is find a data sheet for your steel and stick to it religiously. For simple carbon steels, O1, 1080, 1095 and the like, you need to get them just a bit past the curie point, about 1500f, then quench. Keep a magnet next to whatever heat source you're using, once the blade doesn't stick to it it's hot enough. Don't go by color! Color is nearly useless, doubly so when you consider that the color a blade glows will change depending on the ambient light.
What quenchant you're using is almost more important than the temperature. Don't fall for the internet crap, a bucket of used motor oil is not what you want to be using. For most oil quenching steels, which is what most plain carbon steel are, a few gallons of warm canola or peanut oil will work beautifully. However, some steels require a faster quench, steels like 1095, the w series steel and the like. Quenching a 1095 blade into canola oil, especially if it cold/cool, will result in exactly what you're describing; a blade that's been sorta hardened but not really. For these steels, you need something that'll cool the blade faster. For most people, that means water or brine, which also means a lot of cracks. If you plan on working with a lot of 1095 or the like, I recommend investing in a bucket of Parks 50. It's expensive at $150 a bucket, but I've never lost a blade in it. Long story short, make sure you've got your austinization temperatures right and make sure to match your quench medium to the steel |
#4
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Epic, nonmagnetic is 1413 degrees a far cry from 1500. That is the problem with a forge. O1 doesn't need a fast quench oil, canola heated to 120 is fine for it. Steels I would HT with a forge are 1084, 52100 and O1. Also add in 80CrV2 and 5160.
HT is an art as well as a science, especially with a forge. Blitt are you still using O1? Last edited by jimmontg; 10-22-2017 at 05:48 PM. |
#5
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Thanks guys, I'm using 1080. I took it up to mom magnetic then let it heat up a bit more and right into warm mineral oil. I could still see the steel glow in the center while in the oil so I'm thinking it didn't cool quick enough. May be I'll try canola oil instead
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#6
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Yes mineral oil is to thick. Good call.
__________________ Now it says Guru and it used to say Master. I think I like Master better, though skilled would be the best description |
#7
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Thats why i said a hair past
1095's temp is 1475, O1 is 1475-1500, 1084 is 1500. I said 1500 because its the lowest temperature thatll harden the widest range of steels. Heating to 1500f is a good target for most plain carbon steels, thats why i used the number i did |
#8
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01 should not be considered a "simple" simple steel due to the number of alloys in it, though it is often is addressed as such. 01 requires more than just a simple heat, quench, and temper HT if optimal results are wanted, and it should never be taken much beyond 1475? for the hardening quench due to the possibility of putting more carbon into solution than is really needed.
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#9
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Right Epic, but how long do you hold?
You said using colors to determine the temperature is a waste of time and l would tend to agree if you don't have a lot of experience heat treating. I was the HT for a machine shop and we used an oven. I got pretty good at determining the color for O1 at 1475 which is it's sweet spot. I always darken the room when forge HT so I can see the color better. Still could be off by 100 degrees which is why we have magnets, but a practiced eye will try to keep it below 1500. O1 though needs to be held at 1475 for 10-15 mins which is impossible in a forge. That hold time makes O1 an optimally better blade, but still its a decent blade with a forge HT.
But basically as you said, take it to nonmagnetic and hold for a bit longer, but of course some steels like 5160 are best taken up to 1600 so you would hold that longer still. That is why I believe there is an art factor to it when using a forge. Some steels are made for a forge it seems, like the aforementioned 5160 or 52100, 1084 and L6. I forgot about L6 as it is uncommon now, but it is great in a forge. Always look at the data sheet for a steel to determine its optimum hardening temp and then go from there and practice. |
#10
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Got it to harden had to go a lot hotter than I thought....any thoughts on the grain
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#11
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Hi Blitt
I'm no pro and the picture is a bit shaken, but it doesn't look to good. When I tried HT 1095 I also got it to harden after reaching very high temperatures, when the blade broke the grain looked a lot like yours. I used cold canola oil for quenchant. This is an file that was used for the test, but it gives an idea of the grain. I got significantly better and more consistent results when I started heating my canola oil to 130 F. If you aren't doing that, give it a try. Do you normalize your blade before HT? Last edited by Rasmus Kristens; 10-24-2017 at 03:22 AM. |
#12
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Honestly all I did was take a small piece of 1080 bar stock and tried the heat treat on that no forging was done on it so I figured it was already normalized
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#13
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Yea it properly is.
Guess its to high temperature then? Did you use mineral oil for quenching for the piece in the picture? |
#14
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Blitt you shouldn't be able to see crystalline structure, it should look like grey velvet as shown in Rasmus' picture. Also a trick to use is to put a barbecue regulator on the propane and turn the flow down for HT as forge temps at 1900+ aren't needed. The low flow regulators cost about $25 at Lowes. It takes practice. but you can get a surprising amount of heat control using a regulator.
Last edited by jimmontg; 10-24-2017 at 10:22 AM. |
#15
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I used canola oil I kept quenching but is wasn't getting hot, so I heated it up more and it hardened but I guess I got it too hot
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Tags |
1084, 1095, 52100, art, bee, blade, carbon, cold, edge, file, forge, forging, harden, heat, hot, knife, make, motor, problem, quenched, question, simple, steel, temper, water |
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