Waited too long to temper?

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smorgan345

Joined
Mar 8, 2007
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Im using 1080, stock removal. I hardened last nite, got them up to 1500 and quenched in oil. I ran out of time and wasnt able to temper until today. 405 twice for 2 hours. I know you are supposed to temper as soon as possible after the blade reaches room temp after hardening. What effects does waiting this long have on the steel? Retained austenite is a problem created during hardening if i understand correctly so Im guessing its not that. Would allowing it to sit too long enable a further transformation of the martensite into something less desirable? Thanks for any input.
 
With 1080 I think the biggest risk is really just breaking it due to how brittle it will be. On the other hand, I'm no expert and kind of curious what the resident experts have to say on this. So far I've always managed to get the temper done in a timely fashion but I can definitely see running into the same situation you did.
 
I am definitely no expert, but have done a little research on this issue. It seems that some steels are more susceptible to stress fractures or cracking between the time of HT and Temper. As understand it, laminates and steels that require rapid heat extraction have a higher probability of cracking due to rapid heat exchange. I also read that if you live in a cold area the risk increases as the blade temp drops with the ambient temp. So where I live we got snow yesterday, I wouldn't want the blade to drop down to 32 Degrees F before I temper it.

Blades can shatter, but I think the bigger concern is internal stress fractures (Not visible to the naked eye) But will definitely affect the integrity of the steel.

now hopefully the experts will come in and tell me where I am incorrect!:o
 
I have seen water quenched 1095 and 1.2% file steel crack about 30 minutes or so after the quench before. Just from laying on the bench before tempering. It was arrow straight and perfect out of the quench.That was back when I had to learn everything the hard way. Now when I quench hyperE steels I practically jog to the(pre-heated) oven, just to be on the safe side ;)
 
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Wow, so the fact that i washed the quench oil off with water before the temper was really bad!!! Believe it or not, i have done my research, i guess i just didnt recall the importance of not letting it cool down to much after the quench. I wanted to temper 4 at the same time so i suppose the first would have hit room temp by the time the other 3 were quenched and ready.
 
Now, I dont personally think just stopping to wash off the oil on oil quenched 1080 would be that bad.I cant comment on leaving overnight though.Remember, I was talking about water quenched 1095 and 1.2% carbon steel breaking after the quench..Some noticable difference there in stresses there..
 
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smorgan345 said:
Wow, so the fact that i washed the quench oil off with water before the temper was really bad!!! Believe it or not, i have done my research, i guess i just didnt recall the importance of not letting it cool down to much after the quench. I wanted to temper 4 at the same time so i suppose the first would have hit room temp by the time the other 3 were quenched and ready.
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I would guess that may cause problems, but when I think about it. the shock the steel went through washing off the oil is microscopic compared to the shock during HT. It may relate to the structural make up of the steel at the time of "Shock" I want to relate it to Glass, very brittle and when warm glass is put in cold water it shatters! I could be way off on this analogy.
 
Huh, so I guess I've been smart by accident by just wiping them off gently and getting them into the temper oven within a few minutes. I'm using 1080 with canola oil as a quench. Wipe and let it sit for maybe ten minutes at most if I've got a couple more to do first. I normalize everything I'm heat treating first, then do the actual HT, so with the fairly thin 1080 it's fairly quick for each blade at that point. I'll have to keep this in mind for when I start using other steels with a soak time. It's not like I can't put one in the temper oven and go back to HT the next.

And this is why I love this place. :)
 
So i guess the big question is, should i bother putting handles on them? I was supposed to send them off to friends but i dont want to send something that is going to be defective and break due to invisible internal stress fractures. As my father used to say...'if you aint got it here (pointing to his head), you better have it here ( pointing to his back)'
 
They are not hurt at all. I many times quench at night just before leaving the shop and then temper the next day. I have never had a blade break from this. I have had blades break when experimenting with different quench mediums when not tempered right away though. So if they didn't crack setting over night then just temper them as normal and proceed.
 
Relax, your blades are fine.

In hyper-eutectoid steels, the problem is one to concern yourself with. If the steel is low alloy, it gets even worse. Add a water quench and the situation dictates very prompt tempering.

Now for eutectoid steels, like 1084, and with most 1084 alloys having enough Mn and other things to deepen the hardening, there really isn't a big worry. Wash them off, and temper when you can. If you have to go to bed, do it tomorrow. If you don't think it will get done for several days, do a snap temper by putting in the oven at 300F for 15-30 minutes. That will stabilize things for the short term.

With all carbon steels, dropping them or trying to straighten a warp/twist before tempering often ends badly.
 
Sorry if I caused some stress! The Experts showed up!
I should have just said some steels are more critical than others, 1084 should be fine. But I would temper as soon as possible just to be on the safe side! Smorgan are you going to show us a photo of your finished blade?
 
Been away for a while, new addition to the fam! I do intend to post pics. believe it or not, I have not finished them. I just have to sharpen and polish and Ill post some pics.

RyanW said:
Sorry if I caused some stress! The Experts showed up!
I should have just said some steels are more critical than others, 1084 should be fine. But I would temper as soon as possible just to be on the safe side! Smorgan are you going to show us a photo of your finished blade?
Click to expand...
 
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