heat treating cycle for 52100

[1984nitro]

I am looking at forging and using this steel for my knife but can't find much info on heat treating for knife.
Any info would help
Eric Knight

 

[Karl B. Andersen]

http://www.engnath.com/public/harden.htm

scroll down the page here just a little bit and find 52100:
http://ajh-knives.com/material.html#metals

http://www.tellercanyon.com/process.html#ToC5

 

[Kevin R. Cashen]

Forging: 1700F to 2100F, the folks who designed the stuff recommend that you not forge below 1700F.

Hardening: Heat to 1550F and quench in oil. (have a neutral to carbon rich atmosphere or intend to remove some material after the heat treatment)

If proper soaking was achieved and the temp was spot on the following tempering schedule should apply: 420F=60HRC, 450F= 59HRC, 500F= 56HRC.

Beware of overheating as this steel is very prone to retained austenite. My own personal tests have found that it can get as hard as 67HRC but as you increase the austenitizing temperature it will do the opposite of what you think it should and will start dropping in hardness. Because of this it will respond to cold treatments and multiple temperings. It is also very prone to forming grain boundary carbide resulting in unnecessary brittleness. It is a quirky steel designed for a rather specific task in industry, and not really the steel to pick if it is your first try at knifemaking. There are no huge mysteries surrounding the steel despite the popular mystique, it still follows all the same rules of iron-carbon systems, just it insists that you also follow those rules a little more closely than other steels.

 

[Guy Thomas]

Any tips on minimizing the brittleness issue from the grain boundary carbides? Keeping the grain very fine? Proper soak times?

 

[1984nitro]

thanks for the info. I have been working with 1095 for awhile now and love the results I have been getting. I just want to start learn a different steel along with 1095 and after reading engnath website and looking on Ed webpage it seem 52100 would be a good one to try out.
Thanks again
Eric Knight

 

[Kevin R. Cashen]

Any tips on minimizing the brittleness issue from the grain boundary carbides? Keeping the grain very fine? Proper soak times?

Avoid slow cooling from Accm. Stuffing a forging into your hot gas forge after it is shut down and walking away for the evening would be VERY bad. I would also avoid the whole vermiculite/wood ash thing unless you do it isothermally (e.g. cool quickly from high heat to 1100F and then slow cool- not all that practical for most smiths). Spheroidizing would be the way to go.

 

[Guy Thomas]

Ok, thanks Kevin, sounds like the normal air cool thermal cycling would be o.k. then. I have some 52100 at the house I've been meaning to work with more but this steel is definitelty not my favorite to forge.