Grain refining O-1 tool steel

taylormadeknives

taylormadeknives

Well-Known Member
I'm curious if anyone has any temps they go with for refining the grain in O-1 tool steel. I have been going a hair above austenizing temp say 1525, then air cool, back in at 1475, air cool and so forth dropping 50 degrees with each cycle down to 1275. Once done cycling the steel I go back in at 1450 for 10 min to Austenize then quench. I have been getting good results, but I'm kinda flying by the seat of my pants on these temps. Does my process sound about right? Anyone who has a lot of experience with O-1 tool steel on here who can point me in the right direction. I haven't used a whole lot of it myself and want to make sure I'm getting the most out of it that I can. Thanks!

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I use O1 with Vanadium added and have yet to see a need for grain refinement in doing stock removal straight razors. I take my edges to 30K grit, then proceed to strop on Chromium (.50 micron) balsa strop, .25 micron diamond on rock-hard felt, then onto a tight-grain leather razor strop. The edger are fine enough to whittle hair and give very smooth shaves. In using one of these blades, I shaved every other day for 6 months before needing to see the hones again and only kept it up with stropping.
 
Mike is correct. If doing stock removal with 01 there is no need to refine the grain any farther than it is. The grain size is very fine as it comes, so long as it is precision ground and spheroidized annealed bar stock. I have found that a one hour stress relief at 1200° to 1250° with an air cool after all grinding is done seems to prevent or lessen warp in quenching. You can do as you please, but in my experience the following has given me fine results. After the stress relief, the blade is coated with ATP-641 anti scale. Then put in the cold oven. The oven is ramped up to 1250° for 30 minutes as a pre-heat, then to 1400° for 15 minutes to allow the oven to soak up the heat a bit, then to 1475° for a 20 minute soak with the count starting once the temp equalizes, then a point down quench in Parks AAA that is at 130°. Break testing shows a super fine velvet like grain structure. Test a scrap piece and see what you get.
 
You may want to do it for other reasons, but there isn't any grain refining going on below about 1400 F in the cycling.
 
Mike, I buy my O1 from McMaster Carr. It's made by Starrett.(at least the package is by Starrett) The composition is: carbon .90, chromium .50, manganese 1.20, Vanadium .20, tungsten .50

Does the O1 you are using have more vanadium than this? If so, where are you getting it?

Thanks,
Ted
 
Thanks for the info guys. I guess I should have mentioned I have been forging it. I have done some stock removal with it, but really prefer to forge it. The way I have been doing it produces a very fine grain, just wanted to see if there was something I could improve on.

Thanks!

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As far as I know, I believe you will find that all 01 has sufficient vanadium in it for fine grain, though sometimes not always listed in general descriptions. The percentages of ingredients will also vary, at least slightly, + or -, with each fresh pour.
 
I wasn't sure if Mike had found a custom alloy or one of the grades that just had a little higher content or if he just meant that since his brand of O1 has Vanadium he isn't worried about grain.
 
with or without vanadium, O1 has very fine grain. Short and sweet heat treat, preheat oven to 1475F, add blade, start timing when equalized. 8 to 10 minutes for 1/16", 20 min for 5/32". Quench in 120F oil. Temper for an hour at 300F. cold water quench, scrub. Temper for an hour at your favorite temperature, 375F gives me Rc 62-63. believe it or dont, O1 looses toughness below Rc61 and doesnt gain it back till Rc54 or less.
 
scott.livesey said:
with or without vanadium, O1 has very fine grain. Short and sweet heat treat, preheat oven to 1475F, add blade, start timing when equalized. 8 to 10 minutes for 1/16", 20 min for 5/32". Quench in 120F oil. Temper for an hour at 300F. cold water quench, scrub. Temper for an hour at your favorite temperature, 375F gives me Rc 62-63. believe it or dont, O1 looses toughness below Rc61 and doesnt gain it back till Rc54 or less.
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Thanks for the reply Scott. I appreciate you taking the time. I guess I have been making it a little too complex. I will be giving this method a try.

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i would get the 11 second oil. I have been using 12 second oil and have had very good results. i got my oil from our lube salesman, a 5 gallon sample. we get our graphite based forging coolant/lube from his company. 11 second should be fast enough for 1084 and 52100.
 
i would get the 11 second oil. I have been using 12 second oil and have had very good results. i got my oil from our lube salesman, a 5 gallon sample. we get our graphite based forging coolant/lube from his company. 11 second should be fast enough for 1084 and 52100.
 
On grain refinement- I would just caution not to get so hung up on grain refinement that you lose site of the much more important carbide refinement, many of the operations for each can be at odds with each other, and if I had to choose between finer grain and finer carbides I would take the later; fortunately we don't have to make that decision. Carbide refinement is achieved through proper normalizing (cycling at temps from 1600F-1700F, and not cooling any slower than an air cool). Grain refinement is done by cycling at temperatures that do not exceed the grain coarsening temperature which is not as static. There are even methods that can be utilized below even the Currie point, that will germinate new grain growth within the existing grains in a condition referred to as "duplexing" this can pile up new points of nucleation pretty quickly. We just need to be aware that low temperature cycling will tend to segregate carbide if we are not careful; that is, after all, how spheroidizing works.
 
If I'm buying flat ground annealed O1, should I normalize it? If so how many cycles and at what temps?

If low temp cycling segregates carbide should we not be doing multiple temperings on some steels?

Thanks,
Ted
 
Smallshop said:
If I'm buying flat ground annealed O1, should I normalize it? If so how many cycles and at what temps?

If low temp cycling segregates carbide should we not be doing multiple temperings on some steels?

Thanks,
Ted
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I would only bother with it of you feel there was some issues left from the mill, most tool steels like O-1 are pretty darned good as is, if it were a simple carbon like 1095 I would say a normalizing would be in order but not necessarily the case with O-1. When I say "low temperature", I mean temperatures at which more diffusion can occur, around 1275F to 1450F. Above that, rapid diffusion puts thing into solution and homogenizes, below that, diffusion to too slow to do much more than make tempering carbides or fine spheroidal structures.
 
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