A-2 Hardness

If A2 stock is very thin stock like 3/32 or 1/16 I have learned to air quench it. It often warps in plate quenching if it's thinner than 1/8.
 
Thanks Leu. I was thinking of something along the lines of what you make, with the single chisel grind with no secondary bevel. Man that would take a while to finish if you had to leave it at 1/32" before heat treating.
 
Like I said there are a lot correct ways to do this stuff,, I learned from old timer machinists at my work,, a lot of what they told me had to do with toughness more than edge retention, so I have had to tweak aot and develop my on Protocol that gives me what I want in a blade,, If you follow anyones advise A2 is hard to mess up,,, if you have digital kiln,, but can be refined,, that is where people like Mr Leu.. Come in,, Much Respect,,,, just make blades and keep records and change what you need to make things fit You..
 
me2 said:
Thanks Leu. I was thinking of something along the lines of what you make, with the single chisel grind with no secondary bevel. Man that would take a while to finish if you had to leave it at 1/32" before heat treating.
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if you have a belt grinder it won't take long at all :) Several passes with a 40 grit belt after heat treatment.
 
I think also with plate quenching Air hardening steels, depending on how you're grinding your blades and whether you're stress relieving first before heat treating, your blade could not only warp (the usual way) which can be straighten out with a vise, but blades can warp from left to right or right to left (when the blade is laying flat!) :eek::eek: Happened to me a few times and I haven't bothered plate quenching since.
 
Thanks for the replies and the A-2 specs provided. The comment about thin blades warping raises a new question.

What good is plate quenching A-2 if it may increaese the chance of warpage with thin blades. I thought plate quenching would help prevent warpage. (I already bought some plates)
Is it mainly to speed up the quench so you can get to tempering faster? My understanding is that A-2 and D-2 are alloyed so they will harden to 63 or 64 in still air. Is that not always the case? If you get an extra point or two of hardness with plate quenching or cryo, wouldn't a 500 degree temper bring it down to 60 rc in the end anyway?

I also have an unrelated question, if I may mooch a little more time from anyone.

If I foil wrap my blades, can I put them in my kiln cold and bring it up to the preheat temp? Is there any harm in this? It seems to me that opening the door to put them in after it has been heated would just cause loss of heat and extend the time in the kiln. Thanks.

Gerry Hamrick
Snohomish, WA
 
gshamr said:
Thanks for the replies and the A-2 specs provided. The comment about thin blades warping raises a new question.

What good is plate quenching A-2 if it may increaese the chance of warpage with thin blades. I thought plate quenching would help prevent warpage. (I already bought some plates)
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S'why i don't bother anymore with plate quenching! The blade can be perfectly flat, but then you find out that it warped to the right or left ! (which is a weeeeeee bit harder to straighten)

Blades that are stressed relieved however probably do not have this problem due to the uneven grinding pre heat treatment.

gshamr said:
Is it mainly to speed up the quench so you can get to tempering faster? My understanding is that A-2 and D-2 are alloyed so they will harden to 63 or 64 in still air. Is that not always the case? If you get an extra point or two of hardness with plate quenching or cryo, wouldn't a 500 degree temper bring it down to 60 rc in the end anyway?
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It's to speed up the hardening I suppose to achieve a higher as quenched hardness, but like you said, you'll end up drawing it down anyways to 60. I still air quench the blades and prior to tempering, they are very hard, harder than files for sure by A LOT.

gshamr said:
I also have an unrelated question, if I may mooch a little more time from anyone.

If I foil wrap my blades, can I put them in my kiln cold and bring it up to the preheat temp? Is there any harm in this? It seems to me that opening the door to put them in after it has been heated would just cause loss of heat and extend the time in the kiln. Thanks.

Gerry Hamrick
Snohomish, WA
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This is how you should do it. With the blades in the kiln at room temperature and bring it up. I think A2 works better than to just shock the hell out of it loading it into a HOT kiln, the transformation does better ramping up at a decent time.

opening the door to the kiln will decrease the loss of heat and not to mention loading the blades into a very hot kiln and trying to get them on end, is a bit on the more difficult side and could cause more possible burns to yourself.
 
Interesting stuff, fellas.

There's a toughness peak at 500 F which will give you 60 HRc, so that's where you go !
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A2 peaks at 41 lbs at 55 and 60 HRC and drops off in between.
At HRC 58 the Charpy C -notch test for A2 drops to between 29 and 33 lbs (per Crucible Data Sheet).
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I note that Latrobe's spec sheets show an impact maximum at more like 58 Rc, and a minimum around 56 or 55. But then I don't recall off hand their soak temp...

http://www.latrobesteel.com/assets/documents/datasheets/LSS_A2.pdf
 
I prefer plate quench because the blades come out "cleaner"-less oxidation to the surface than air quenched. You don't have to fight the SS packet to get the blade out while still hot from the oven.

The Latrobe data sheet is significantly different from the Crucible http://www.crucibleservice.com/datash/dsA2v12.pdf one and the Uddeholm that I linked earlier. See the second page of the Crucible sheet for a table of strength vs hardness.
 
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