Heat treat questions & terminology

flatgrinder

flatgrinder

Joined
Dec 20, 2005
Messages
2,045
Hi,

Just taking a look at Crucible's datasheet on S30V:

http://crucibleservice.com/products/CPM/toolSteel/stainless.cfm

What do they mean by "equalize" in the Pre-heat section? Is that "heat for a certain amount of minutes?" If so, how many?

Under Austenitizing: 15 to 30 minutes is quite a large difference in time frame. What do you recommend and use? Notice any difference? Also, there's a difference/ choice in austenitizing temperatures that vary 1000 degrees. The higher temps result in higher hardness -but does it cause grain grow and a weaker / more brittle edge?

Under Quench: What is an interrupted oil quench?

What kind of Rc do you aim for? Is there a noticeable difference in performance between Rc 57 and 60?

Thanks!
 
I took a look at Crucibles chart.Are you sure you are reading the specs right? The Austenitizing temps are from 1900 to 2000F (that is a normal spread) They are also posted as 1040 to 1095C,that is in centigrade (same as 1900-2000F).The equalizing time is to allow the steel to become completely and evenly heated to the preheat temp.Thinner steel=shorter time.The soak time is related to the austenitization temp.Higher temp= shorter time.An interrupted oil quench is when the object is plunged in quench oil for 2-3 seconds and then removed and air cooled.This quickly drops the temperature part of the way down to start the conversion to martensite.Plate quenching does the same thing and helps avoid warping.The tempering temperature can be varied from 400 to 1000F.This will result in a range of final Rc hardness. Most knives are tempered at the 550F-650F area.BTW,The chart you want is to the right of the info on HT.Rc can be targeted by the soak temp and the temper temp from Rc64 to Rc57.A good set of temps would be to austenitize at 1950 ,plate quench,double temper at 600 with cryo in LN and you should get a RC59-60.Hope this helps you out,
Stacy
 
If you look at the chart for the steel, it will have columns for 1900 - 1950 and 2000 (S30V maybe?) Under each temperature is a time at temperature spec. I believe 30 min for 1900 and 1950 and 15 min for 2000. (Check that first - I'm only half way through my first coffee.) The different austenizing temperatures lead to different tempering charachteristics. Sometimes the Time at Temp tables scare the crap out of me - but they haven't failed me yet?

Rob!
 
Flat Grinder, I posted my 30V heat treat recipe last night under S30V vs S60V. do a search and it will come up. I use a higher temp and longer soak time than the data sheet calls for. This works in my furnace with a foil pouch and air quench. You might want to start a little lower and do a shorter time for a few to characterize the material in your furnace. Sneak up on it. I found 30V to be very forgiving and have even run it at 2130 and 20 min soak time. Using a 400 temper I got a finished hardness of 62 and blade cut like a bastard and was still pretty tough. I am still playing with this. I use a Ln2 cryo right after it comes to room temp after the air quench. My recipe is based on this cycle so again if you don't do a cryo then maybe you need a few more tempers....PHIL
 
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