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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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normalizing before heat treat?
Is there any benefit to normalizing a blade before heat treating it. I'm using 1080, 1095, and o1.
Thanks, KJ |
#2
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Kyle, Ive had a couple knife buddies tell me to Normalize before HT when I first started. I always Normalize before HT now. I think it would be a shame to spend valuable time to create such a nice blade only to have it warp on you. Normalizing is one Easy step to help any chance of that not to happen.
Shane |
#3
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Does it help any with the hardening, or grain refining?
KJ |
#4
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It does help with the grain refining, especially if you do it three or so times at a slightly lower temp each time. It's very good to do this before heat treating, both for the grain and to prevent warpage like Shane mentioned.
__________________ ~Andrew W. "NT Cough'n Monkey" Petkus |
#5
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If you are doing stock removal it isn't all that important .If you have forged , it is highly recommended to produce a uniform structure and to relieve stress therefore minimize warping.
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#6
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Even if using the stock reduction process (not forging), I would suggest that normalising is still a good idea.....Steel for stock removal has gone through a heat process somewhere in manufacture....and the grain may need refining. Grinding from stock can also could aslo cause some uneven stresses and normalising may help........
Otherwise I agree with AwP.....I normalise three times before ht....... __________________ Kevin Davey |
#7
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Normalizing
Some materia used for stock-removal blades is annealed to make it easier to work with. If so, the annealing will create large carbides which should be dissolve by normalizing prior to hardening. Note that some some steels, particularly ones with carbon in excess of 1% will probably always have large carbides and in this case, these carbides enhance the abrasion resistance. However, normalizing is almost always a good practice.
__________________ Which is worse; ignorance or apathy? Who knows? Who cares? |
#8
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I have seen on O1 data sheets "do not normalize". Can anyone explain to me why that is (O1 mind you)????
Thanks. RL |
#9
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I wonder if "do not normalize" means it's not necessary or does it mean it's detrimental .It would come spheroidize annealed .I can't think of any detriment to normalizing .Of course bladesmiths do many things I don't think necessary !!
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#10
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I had a friend visit my shop recently, and we discussed the benefits of normalising...but discusing isnt nearly as good as seeing the results for yourself....so I did a simple experiment to show him.
I took a piece of 5160 and over heated it in the forge..not too welding temperature, but above critical.........I then quenched it to harden and snapped a piece off. The sample on the left side is the result....very visible grain growth. I then took the same piece of steel that had been over heated (same enlarged grain) I then normalised three times.......then heated to critical and quenched...The sample is on the right side. As you can see, there is a huge difference in grain size....proof to me that normalising is beneficial. I polished the other end of the sample pieces and you cannot tell them apart. Kevin. __________________ Kevin Davey |
#11
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Good photo of your experiment Kevin! Thanks for showing it.
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#12
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Quote:
You will often see this on L6 data sheets as well, I believe the concern they are conveying is that the treament that would be normalizing in many other steels would in this case be a hardening operation. Also remember that industry will often heat to 1600F +to normalize, I have far too many bad memories from heating O1 to temperatures higher than 1500F and then letting it air cool. In any subsantial cross sections O1 will crack pretty bad by air cooling to bellow Ms from such a temperature. If you have forge welded the stuff, for example, you really need to step it down in cycles before you let it go cold, if you want it in one piece. so I "normalize" these steels, just I do in cycles and make sure that I decrease the temperature on each heat. This is not the traditional concept of industrial "normalizing" so one could understand why the tradional method would be avoided. |
#13
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Thanks for the photo Kevin!
That picture is worth a few thousand words. Steve |
#14
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Nice pic Kevin, thank-you. Thanks for clarifying Mr. Cashen.
__________________ "Many are chosen, but few are Pict" "The doer alone, learneth" NT Neo-Devo |
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blade, forge, forging, knife |
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