154cm HT question

panch0

panch0

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Jun 16, 2008
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I heat treated two blades at the same time, which I have done many times before. They were both 154cm from the same place but different bars. Both were labeled 154cm. After heat treating and tempering the blades the smaller one seems harder than the larger one. I have a 60rc file and it just scratches the smaller one, but cuts deeper on the larger one. I have a brass bar and the larger one rolls the edge and the smaller one is just fine. I am going to HT the larger blade again to see if it has to do with it coming out of the oven. I am pretty quick at taking them out and applying the aluminum plates. Anybody have any ideas on what could be happening? Thanks!

Edit: I used a file to gut in one of the holes in the handle area and it seems to cut less deep .
 
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My guess is that one of these steels is not like the other.

Did you let the oven come back to temp before removing the second blade? Which blade came out first? Did the file cut before or after tempering? What was your austentitizing temp? Tempering temp?

154CM will harden in air, so you probably don't have a problem transferring from the oven to the plate.
 
I ramp up to 1400 and hold for 10 minutes then proceed to 1925 for 30 minutes. I then pull out both packets and lay them on the plates then cover and apply light pressure so I get good contact and leave them there for two minutes minimum. After they get to ambient temp they go into Alchohol and dry ice overnight. When they come out of the freeze and back to room they get tempered for 2 hrs at 400 degrees twice. That has worked great for ats34 and would get me 59-60rc. I am worried that the two bars are different steels.
 
Nothing wrong with your recipe Frank - and I doubt it has to do with speed out of the oven. I do as many as six without problems. I'm guessing you would have mentioned it if there were some sort of catestrophic envelope failure. Two blades in the kiln at once largely eliminates oven error. There seems to be a concensus building to suspect that bar.

Rob!
 
The place I bought this steel at sells pg 440c and pg 154cm, I wonder if 440-c was sent to me instead. I haven't heat treated 440c yet, but seem to recal it takes a lower austentize temp. Does anybody know the effect of HTing 440c like 154 cm? Another think I failed to mention is I glanced over at the PID control during tempering and it spiked up to 416 degrees for a minute or two until it leveled out.
 
panch0 said:
The place I bought this steel at sells pg 440c and pg 154cm, I wonder if 440-c was sent to me instead. I haven't heat treated 440c yet, but seem to recal it takes a lower austentize temp. Does anybody know the effect of HTing 440c like 154 cm? Another think I failed to mention is I glanced over at the PID control during tempering and it spiked up to 416 degrees for a minute or two until it leveled out.
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Most people austenize 440C at 1875F. It does take lower tempers - in the range of 350F depending on what you're looking for. However, a number of sources show tempering range from 1850-1950. Austenized at 1950, it actually behaves much like 154CM, coming out of cryo in the 63+ range. Done at those temperatures, it would come out of a 400 degree temper around 60/61.

Rob!
 
The 416° shouldn't make a big difference. Maybe a point in hardness. I'd agree that it's different steel. If you have any scraps of the questionable metal, you could send it in and try to figure out what it is.
 
zaph1 said:
The 416° shouldn't make a big difference. Maybe a point in hardness. I'd agree that it's different steel. If you have any scraps of the questionable metal, you could send it in and try to figure out what it is.
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Where could I send it for testing?

I have been short on time lately and have been working on this knife for a while now. I just hate that I will probably have to start over, but I ain't got a choice now. I have another bar and a piece of the same bar left. I do a test on the other one before I make a whole new knife out of the second bar of steel. I looks like back to the drawing board. Thanks everyone.
 
If you have a good sized scrap yard near you, you might be able to get them to hit it with a handheld analyzer to at least confirm what you think it is.
 
It could be worse. In my last HT batch I got one blade back marked 46Rc - 416SS. The rest of the 440C, XHP and 3V blades came out just like they were supposed to. It seems the "bad" blade came from a small bar of supposedly 440C I bought a couple years ago just to try it out and finally got around to finishing. The vendor (from whom I no longer purchase anything for various reasons) marks their bars with a grease pencil or paint marker. Another different bar of 440C from them HT'ed fine and seems to hold an edge well, but it has so many tiny inclusions (not sure if that's the right term - they look like little swirls, like when you look up at the sky and see stuff in your eyeball) that the only way to make them look decent is to powder coat them or something. I'm less than thrilled.

I'm becoming really anal about only buying steel that's wrapped and labeled from the mill. I've never had any problems with steel wrapped and marked by Crucible or Starrett. I have about 12 feet of steel in various grades from that same online vendor and I'm more than a little leery about all of them now. For all I know a mimimum wage flunky who doesn't know O1 from his hat is sorting and marking the steel.

EDIT: I'm not naming the vendor here because this isn't the place for it. If you want to know email me. I will say it's not Aldo or USAknifemaker, I've never had a problem with either of them :thumbup:
 
I believe that Matt Doyle has a setup for analyzing steel. You could look him up on here, he just hit 1000 posts a few days ago.
 
Well I re did the heat treat and same results, I even put a piece of the other stock I got and it didn't harden past 60rc according to my 60 rc file that cut into the steel. now I need to get some more steel and start from scratch. This really sucks! Where can I get some 1/8" pg ats34 or 154cm? I wish I had a way to test my evenheat to see if that was the problem.
 
Thanks bro, I haven't even tempered the blade yet and it is still softer than my 60 rc file.:mad:
 
It may be that you've got a higher heat alloy and you're never reaching austenitizing temp. If you can find out what it is without spending a ton of cash, it might not have been a waste. Or it could be that you got something unhardenable.

Does a magnet stick to it? Do you have a spot on the tang you can try to drill it and see if a HSS bit will cut?
 
Ok the magnet does stick to it and a regular bit won't drill into it at all. I drilled a hole in some annealed steel just fine with it.I ground away some of the edge and resharpened and the 60rc file will kill the edge but when I cut a sliver off some deer bone the edge doesn't roll, the brass bar will roll it though. I think I just entered the twilight zone, or am I expecting to much out of this steel?

BTW how many times could I heat treat 154cm before its no good?
 
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panch0 said:
I wish I had a way to test my evenheat to see if that was the problem.
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If one blade turned out fine - and the other didn't, I think that takes your oven out of the mix.

FWIW, I recently ordered several bars of ATS34, and got S30V instead. (It was actually printed on one of the bars)

What's confounding me is - what stainless won't harden nicely from 1925 with cryo and a plate quench.

Weird! :confused:

Rob!
 
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