52100

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52100

Postby James B Smith jr » Sun Nov 12, 2017 8:24 am

What would be the optimum hardness for 52100 and how to get it there. James B Smith jr
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Re: 52100

Postby Kevin R. Cashen » Sun Nov 12, 2017 11:48 am

What type of blade? The application and expected use will play a large role in determining the target hardness. Although, 52100 is geared toward high strength and abrasion resistant activity, so I would say that if you are going for less than 60-61 HRC that you should probably consider another steel.
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Re: 52100

Postby James B Smith jr » Sun Nov 12, 2017 6:11 pm

I only want to use the 52100 as a slicer. James B Smith jr
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Re: 52100

Postby Stuart Davenport » Mon Nov 13, 2017 1:15 pm

I leave all my dedicated 52100 protein slicers hard. 63-64HRC. 52100 hunters, 62HRC. I've even wondered about leaving SOME dedicated protein slicers at almost as-quenched hardness, around 66HRC, but 99.9% of my blades are for customers who I don't know their ability to handle a thin and exceptionally hard blade that well and what cutting substrate they use.
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Re: 52100

Postby James B Smith jr » Tue Nov 14, 2017 8:21 am

Can Peters Heat Treat do a good job heat treating 52100. At 64 how does 52100 compare to m4 both blades just alike and sharpened just alike.
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Re: 52100

Postby Stuart Davenport » Tue Nov 14, 2017 1:32 pm

Peter's does a good job on the steels I've sent them (AEBL, M4, Elmax), no experience with their 52100 HT.

What 52100 are we talking about? Is the knife just stock removal from annealed 52100, or was the forged out from 52100? If the knife was forged, then a normalizing and cycling heat treatment needs to be done prior to hardening. Also, there was some 52100 from Aldo (New Jersey Steel Baron) some time ago that needed a normalizing heat before hardening, due to the fact it was so heavily spheroidized from the mill. Because of that issue, ALL of his carbon steels that I use get normalized and cycled prior to hardening, because AFAIK, that issue has not been addressed.

If you bought 52100 in annealed bar stock from Alpha Knife supply, their steel is ready to harden as received, no need for normalizing/cycling.

I would call Peter's and ask to talk to Brad Stallsmith. He is their cutlery HT manager. Ask him what they offer (do they normalize and then thermal cycle the steel? Also, do they use the low end austenitizing temperature of ~1475f? Or do they harden 52100 hotter than it should be hardened at ~1550f?)

Not an easy answer, I know, but it will depend on a few factors.

As far as comparing 52100 to M4, M4 will have better corrosion resistance, although it is not stainless. M4 will have better overall wear resistance. 52100 will be slightly easier to sharpen to a fine edge and easier to maintain that fine edge, although I don't find M4 to be too problematic. I am using M4 in the kitchen right now, and like it quite well, but I also like 52100 in the kitchen.
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Re: 52100

Postby James B Smith jr » Tue Nov 14, 2017 3:32 pm

The 52100 steel came from AKS. I emailed Brad about what Temp they used. I know on their compatable sheet they say they heat treat oil steels at 1575 degrees. I have a friend that lives close that Heat Treats his on blades. . Would you say to 1475 and soak how long. It will be a thin blade .070 or less. I think He has Liquid Nitrogen.What temps to temper and how many times.?
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Re: 52100

Postby Stuart Davenport » Wed Nov 15, 2017 1:35 pm

1575f is way too hot for hyper eutectoid carbon steels. Too much carbon in solution, a lot of plate martensite instead of lathe martensite, too much retained austenite in the matrix, and a lower hardness level than it should be. Before I had a kiln that would hold a good temp, and Parks 50 oil, I made a blade out of Hitachi White #2 and sent it to them for HT. Out of all the knives I had made for myself (well, for my wife anyway) in the kitchen, that was the only one that would not hold an edge to save your life. I then learned they hardened it at 1575f. No wonder that knife sucked. They do use LN2 on every steel, if I recall correctly, so the retained austenite will be dealt with, as well as a bump in HRC to get it back where it should be. But the microstructure still isn't what it could/should be. ie large aus grain.

However, they are doing a LOT of volume. And when you have blades coming in that may be heavily annealed, or FORGED, instead of doing a normalzing/cycling HT (which is more time and energy for them), they may be dealing with the spheroidizing and forged blades all at one go with that high heat. I really think that is why they use 1575 instead of 1475. That is why a knife maker will do a better HT than Peter's can. With the amount of knives they are HTing, they have to figure a way to make it economical for them. For us knife makers, we are after the absolute best we can do.

If your 52100 came from AKS, soak it at 1475f for 10 minutes. Your tempers will be something I recommend you work out. It's hard to give temper temp recommendations, because I don't know what your post quench HRC is (how well you did the hardening procedure). I find that I am getting higher HRC post quench than "industry standard" charts show, thus my tempers need to be hotter than the charts show to get the desired drop in HRC. I would walk your tempers up. Start at 350f and test the edge. If it's a little chippy, bump up to 375F and retest.
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Re: 52100

Postby James B Smith jr » Thu Nov 16, 2017 8:42 am

Thank you very much. Should I soak it in liquid nitrogen and then temper to 350 for hour or 2 or temp and then soak then re temper.
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Re: 52100

Postby Stuart Davenport » Thu Nov 16, 2017 1:34 pm

So what are we trying to accomplish with cryo? The main thing is retained austenite conversion to untempered martensite (that gets tempered later). If you temper PRIOR to the cryo bath, you will stabilize the very RA you are trying to get rid of! NO TEMPERS PRIOR TO CRYO!!!! After austenitizing and quenching, once at room temp (or handled with bare hands), it should go immediately into the cryo bath without delay)

However, 52100 using the low range aus temp of 1475f, will have so little RA, that you will likely not see any jump in hardness, and will not need any cryo for RA conversion.

However, cryo with extended soaks (8+ hours) will precipitate nano sized "eta" carbides upon tempering. These carbides are said to increase wear resistance, increase toughness, and give a better cohesion within the matrix between carbides/aus grain. Again, NO TEMPERING PRIOR TO CRYO!!! You can do cryo in between tempers (I really don't think that adding a cryo in between tempers does much for us).
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