W2 Tempering Options

Carterwhopkins

Carterwhopkins

Joined
Dec 12, 2012
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238
I am continuing to fine tune my W2 treatment, I make chef knives. The results from my current routine are good (66/67 after quench, 62/63 temper), but always looking to evolve. I am in a bit of a test mode, since I switched clays from Rutland to satanite.

What is the preferred cooling after temper....air cool or a water quench? I have been doing a water quench, same as my 52100 blades. EDIT - I just found Stacy's post from 2012 - so water quench.

I wait approx 24 hours to do 2nd temper....I put the blades in the freezer, again a routine from my 52100...Ed Fowler said it didn't hurt and could help. Is the 24hrs necessary and what about the freezer.

Any benefit to a 3rd temper session?

Thanks
 
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Rather than randomly trying tweaks to your heat treatment, you need to decide what it is you are trying to improve. Are the edges rolling? Cutting ability or edge retention aren't good enough? You want your knives to have stain resistance? Rather than having a nebulous goal of making it better, decide what it is you want improved and how you will determine if that improvement has succeeded.
 
Ive never used a freezer for w2. I don't think it would be cold enough to do anything? I also water quench after temper, then go right back in the warm oven.
 
Larrin said:
Rather than randomly trying tweaks to your heat treatment, you need to decide what it is you are trying to improve. Are the edges rolling? Cutting ability or edge retention aren't good enough? You want your knives to have stain resistance? Rather than having a nebulous goal of making it better, decide what it is you want improved and how you will determine if that improvement has succeeded.
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Thanks Larrin.

I really don't have any issues with my current routine. My customers are evenly split between professional chefs and home cooks, all comments are that my W2 blades have edge retention similar to the Hitachi White #2 steel (that is good, and I don't know if I could get it to be more like Hitachi Blue #2, if so, that would be better) and that they get screaming sharp without too much effort. My hardness goal is 62-64 and I fall within that range. As mentioned, I changed the type of clay and that has led me to running some test coupons and now blades. I am quite pleased with the early results from the HT and will have a temper # tomorrow.
 
The second temper should follow the first reasonably soon. It won't cause amy real harm to delay the temper with W2, as there is little or no RA. On some steels, the time lapse could stabilize RA. As always, The first temper shold follow cooling to MF as soon as possible.

As far as putting the steel in the refrigerator ... it MAY do SOME SMALL AMOUNT good on higer alloy steels, buy would not make any difference on a simple steel like W2 or on the 10XX steels. The Mf on these is in the room temperature range, or higher. Even on the steels with higher alloying where the Mf is around 0 degrees, the difference between room temp and 0 wll make almost no difference.

Ed and I both agree that putting the blades in the refrigerator won't hurt. We disagree somewhat on wheter it will help any. It ertainly isn't a big enpough issue for either of us to get uptight about.
 
Thank you Stacy, so no real difference in running 2x temper back to back vs waiting a day...guess the idea of the freezer is only good as a place to remember where the most recently tempered blades are.....getting to be a more important factor every year....lol.
 
About water quenching during tempering. I used to do that. Just as a quick way to start the next cycle. I never claimed or expected a performance gain (or God forbid loss) by doing such. But someone recently mentioned (Larrin or Hoss or someone) that some testing showed a slight decrease in toughness at the edge when doing a water quench after temper. Maybe this slight loss of toughness is more prominent if you water quench the very last cycle. So I eliminated water quenches while tempering, just for the peace of mind. I then began wondering if there would be an ever so slight toughness advantage if you just leave the blade in the oven on the last cycle as it cools down after turning it off. Probably would need some super accurate way of testing these different ways of temper quenching.
 
Is the water quench from temper designed to get higher ally steels from the high temper though the embrittlement range quickly? I seem to recall reading something to that effect.
samuraistuart said:
About water quenching during tempering. I used to do that. Just as a quick way to start the next cycle. I never claimed or expected a performance gain (or God forbid loss) by doing such. But someone recently mentioned (Larrin or Hoss or someone) that some testing showed a slight decrease in toughness at the edge when doing a water quench after temper. Maybe this slight loss of toughness is more prominent if you water quench the very last cycle. So I eliminated water quenches while tempering, just for the peace of mind. I then began wondering if there would be an ever so slight toughness advantage if you just leave the blade in the oven on the last cycle as it cools down after turning it off. Probably would need some super accurate way of testing these different ways of temper quenching.
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I would think the drop in temp into that embrittlement range would be negligible. As in, if it’s already tempered at 1000f, the embrittlement range wouldn’t matter. What’s done is done, so to speak. It has already hit 1000f and spent time there, so a drop from 800f down thru 600f wouldn’t matter. But I’ve been educated more than once here!
 
There is some agreement and some disagreement about cooling rate between and after temper. What most agree on is that the difference takes a lab and some really sophisticated testing to detect. The average knifemaker will never know the difference. I would guess the difference is less than 1%.
 
When cooling rate from tempering temperature is a factor it is a big effect. An unmeasurable or statistically insignificant effect is no effect at all.
 
Interesting, what degree of effect do you think it will it make on edge toughness.

I discussed this with Roman, and he felt it was inconsequential. Then again, he is dealing with razor blades made by the millions in factories.
 
I haven’t commented here because the W2 I have been using is different from what is currently available. I did a lot of testing, and am willing to share, but my process is not necessarily going to help your steel.
 
Stacy E. Apelt - Bladesmith said:
Interesting, what degree of effect do you think it will it make on edge toughness.

I discussed this with Roman, and he felt it was inconsequential. Then again, he is dealing with razor blades made by the millions in factories.
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The only effect understood by metallurgists is when tempering from high temperatures, so I would say no effect.
 
Warren, your info is always appreciated here, so if you have the time, for sure we would love to hear your process!
 
What W2 are you using Carterwhopkins Carterwhopkins ? If you don't mind me asking. If you're using Aldo's is it the recent batch? I'm working on my HT protocol for Aldo's recent batch, trying to work out some kinks.
 
I just finished the second temper session on a 10" chef knife, this was the first blade using satanite instead of Rutland cement. This blade came through the process in perfect condition, no warp/twist. I am also getting consistent readings across the entire blade, post quench 66-67 and after temper 63-64. I made 7-8 measurements both times and on both sides of the blade.

As with the Rutland cement, I did a skim coat on the entire blade and then applied approx 1/16" to the areas I didn't want to harden. The satanite does stay on the blade better during the quench. I have not ground or polished this blade, so I can't comment on the visual difference of the satanite.

After reading discussion on ovens in another thread recently, I made a couple of changes to the way I heat my blades. I have an Evenheat 18" with Rampmaster and I do have the rear heating elements. I have now placed a 1.5" thick fire brick at the back of the oven about 1" off the coils, and I also put 52100 bars on either side of the blade holder. This was done in attempt to shield the blades from the coils. I am pleased with the result and think the oven temps may be more uniform around the blades now....pic below.

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I have 8 more blades that I will be heat treating over the weekend and will report and different findings...so far, I am optimistic about the satanite and the new oven setup.
 
I see you did full thickness unprofiled bars. That will make for a lot of post-HT grinding for Rc 63-64 blades. Hope you have a big dunk bucket and lots of belts ... as well as time.

Clean this batch up, grind the knives, and check the hamon before doing the next ones. No use in repeating the same thing unless you know it got the results you wanted. I would suggest doing the blades two at a time to learn how to place the clay and control the hamon.

BTW, are you saying the hardness was Rc 66-67 in the clayed upper spine area, as well as the lower unclayed area? That doesn't sound like you will have any hamon.
 
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