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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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1080 heat treating
I build knives using the stock removal method. I tried some 1080 steel for the first time, I think I will really like it, but my fisrt blade came out a little softer than I would like, RC runs from 55 to 56, can I simply re-harden and temper our do I need to aneal first? I take the blade to a temp slightly higher that non magnetic and quench in 140 degree F ATF, then triple temper at 400 F three times for 1 hour. I temper in a kitchen oven monitoring with a dial type thermometer, the thermometer reads the same as the oven setting. Do I need to reduce temper heat and/or time? A file skates over the blade after quenching
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#2
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1080 is one of the easiest to HT. Typically a steel is hardened from 50-100 F above the non-magnetic point. "slightly higher" is not enough and I'm sure that's the reason for low hardness. Quench and temper are OK.
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#3
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But to answer his first question, he will need to anneal before re-doing the heat treat, right?
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#4
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Probably just needs to normalize.
__________________ Cap Hayes See my knives @ knives.caphayes.com This quote pains me: -- "Strategically placed blood grooves control blood spray in covert deanimation activities." -- |
#5
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Do NOT anneal ! Normalize is optional. The tempered martensite you would start with is a fine grain and just right for rehardening .Normalize wouldn't do anything better.Annealing would mean you would then have to normalize etc.
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#6
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The reason I suggest normalizing is because the heat treat failed. I don't think we know if there was grain growth at this point.
__________________ Cap Hayes See my knives @ knives.caphayes.com This quote pains me: -- "Strategically placed blood grooves control blood spray in covert deanimation activities." -- |
#7
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If he didn't get the temperature high enough that means he didn't dissolve all the pearlite thus the martensite wasn't as hard as it should be.
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#8
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I was getting at something more along the lines of over heating and improper quench media or other quenching problems.
__________________ Cap Hayes See my knives @ knives.caphayes.com This quote pains me: -- "Strategically placed blood grooves control blood spray in covert deanimation activities." -- Last edited by AcridSaint; 11-20-2008 at 05:09 PM. |
#9
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Thanks for the info, sounds like my tempering was OK , I just didn't get the blade hot enough I will go for a shade more red after I loose magnetism and quench, temper, RC test , if the I get a couple more points on the hardness test I will finish the blade and use the brass rod test to make sure I don't have chipping or a permenant deformation on the edge. I'll let everyone know how it turns out. My understanding is - I should end up at 58 or 59 RC.
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#10
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You should get an as quenched hardness of 65HRC... that would be maximum if all conditions were correct, which is tough to do with a forge/torch reality but not impossible.
When your ATF breaks down from use, try canola oil... better yet, a commercial quench oil. It will do better work and last a lot longer. Mike |
#11
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Thanks all, I ended up with a hardness of 58-60 Rc after tempering. Looks like durring my first attempt I didn't get the blade to a high enough temp. Who is good source for buying a couple of gallons of commercial quenching oil?
Dan |
#12
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Quote:
http://www.bladeforums.com/forums/sh...d.php?t=569729 I bought 5 gallons of Parks #50 and Parks AAA from him this past summer. Prompt shipping and a great guy to deal with. -Mike- __________________ "Only two defining forces have ever offered to die fo you: 1. Jesus Christ 2. The American G. I. One died for your soul, the other for your freedom." |
#13
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Quote:
Some times Darren Ellis has Park #50 and Park AAA by the gallon or more. You can get in touch with Houghton International and buy in small quantity (5 gallon). Houghto-quench "K" is as fast as Park 50 and is more stabile. Houghto-quench "G" is a tiny bit slower than Park AAA and is more stabile... AAA will be a little slower than "G" after using a while. If you want smaller quantity of Houghto-quench "G", it is what Brownell's sells as "Tough Quench" and can be bought by the gallon. Don Fogg uses (read this a few years ago so it may be past tense) Brownell's Tough Quench for "fast steels". Scott McKenzie who is Houghton's metallugist and quench oil specialist (posts at BS and SFI) says "G" is plenty fast enough for 10xx steels... like it's rare to quench something over 1/4" at the thick part and most quench oils will handle that. McMaster-Carr has an "11 second" and a "28 second" quench oil in 1, 5 and larger containers. The supplier is Motor Oil, Inc. I've not been able to get indepth information from the seller or the supplier. 11 seconds is not as fast as Park 50 or H-q "K" but may be fast enough... can't tell without further information. Chevron bought Texaco so both company's quench oils are available there. Chevron has bulk plants and bulk plant distributors all over the place. Supposedly some of their quench oils are available in 5 gal. quantity. They have a pretty fast oil and a medium oil, among others. Chevron has been easy for me to get info from. Their website has links for e-mail to tech support. If you live in or near any HT-ing, they may be willing to let you have a small amount for a small amount. They would have oil data so a person could tell what they were dealing with. Mike |
#14
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Thanks for all the help, a gentleman that I made a knife for has field dressed over a dozen deer with his knife, the edge is still sharp enough do do more, I also made a knife for my son, his knife ( O-1 steel) has field dressed 2 deer and an elk , he also cut up and boned all three animals , the edge did need some touching up but was still sharp enough to cut hide with out undue pressure. With all your help I was able to make knives that perform to my expectations.
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#15
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Just a side note, if the blade was overheated it would show higher hardness. It is very easy to fully harden overheated steel due to all the dissolved carbide and enlarged grain size. This is why Rockwell numbers alone do not tell the entire story on heat treating, although it tells considerably more than the much overrated brass rod thing. If the quench is sufficient and the steel did not reach full hardness then chances are that the blade did not reach a sufficient soaking temperature for the quench. If 1500F was reached it would harden fine if under-cooled sufficiently from 1525F and above the hardness would continue to look great but the blade would be brittle and have other issues.
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blade, forge, knife, knives |
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