Problem HT CPM 154

L

LCoop

Joined
May 5, 2007
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Ok I just heat treated my first ever CPM 154. I thought I'd try a new to me steel. I've only used 440C and had great results don't know why I wanted to try something new.

In fact I heat treated my last of the 440C blade today and it came out of the oven, then plate quenched and tested RH 62. Even before DI.

So after reading lots of recipes for CPM 154 I soaked at 1475 for fifteen minutes, then ramped up to 1935 for 35 minutes. Plate quenched on aluminum plates and checked RH and both blades read RH 40

Here's the equip. Homemade electric kiln that works great and tested with the temp pins to be accurate within 5 degrees at many temps. I recently purchased a new Rockwell hardness tester and it's adjusted and it's dead nuts on with my test blocks at 62.5. I've made several knifes this winter with the same equip and all have turned out great.

Any ideas what's happening here. Maybe got shipped the wrong steel. I ordered it from Jantz
On a side note I was using the lower grade foil wrap and had the problem of foil sticking on the bevels of my knife and I have never had that happen before but kinda expected it after reading several threads that it could happen at the higher temps.
 
Your temps should be ok. I have been using 1970 for my cpm154 in my kiln. It could be the wrong steel, but that’s less common than it would seem. Something is way out of whack if the blades are hitting 40 though. I would try a bit more heat, something in the 1950-1975 range, but i believ it still should have hardened from your soak at 1935. Are you testing on the flat of the ricasso or tang? If you are trying to test on the bevels the readings will read way low. Did you grind off the mill scale and such before heat treating or hardness testing? The last batch of 154 I got had some horrible mutant mill scale that was a real bitch to grind off. Way worse and more course than what I have had on my S35vn bars or any other steel I can recall.
 
Thanks for the reply. To answer your questions. Yes I'm testing on the flats and tangs multiple times since I was shocked to see the low RH numbers. I did grind off the areas tested, even buffed to a 500 grit finish. Just like I did on the 440C just minutes earlier that hardened perfectly at 1875. I let the oven cool down to 1400 range, then proceeded to HT the CPM 154 as stated above.

I don't think the steel was even remotely SS. I thought I'd go ahead and try it again at a higher temperature. So I resoaked at 1475 for 15 minutes then ramped up to 1950 and soaked for 30 minutes. When I opened the door and started bringing them out of the oven they warped like horseshoes in the air while I was going to the plates. This was 1/8" stock. The foil this time became part of the blade. There was no way to separate the two. My only guess this couldn't have even been a SS. I don't even have High Carbon steel in my shop presently and actually only had this stock left so I'm 100% sure I was working the exact steel I ordered from Jantz and marked CPM 154 by their sticker. Since it was new to me steel to work with, I waited to do it last. Like I said I actually recently made several knives finishing up my stock of 440C all of which hardened perfectly and tested with my 150A hardness tester.
 
If you tested at room temp after the plates, you were reading steel that was largely austenite. After dropping to -100F, it will be martensite, and considderably harder.
 
Like Stacy said, you need to do a subzero quench before testing. It's extremely soft until the subzero quech as it's not finished the transformation. What hardness are you looking for? I do 1400 for 10 mins, 1950 for 30, plate quench with compressed air and dry ice/denatured alcohol. I've never checked my as quenched hardness but get 61-61.5 with a 550 temper.
 
Thanks for the replies. Wow of all the researching I did on CPM 154 I never saw anything that would suggest a RH of 40 after austenizing at 1935 F and plate quenching only. There's even a graph on Alpha's web site under HT info for CPM 154 that HIGHLY recommends cyro but at all normal austenizing temps I shouldn't be reading RH 40 after plate quench. I even tested my Hardness tester thinking I had damaged the tip or something but it's dead nuts on with test blocks and the 440c knife I heat treated earlier.

Oh well now I know. Thanks for the replies.
 
If you look at the CCC for stainless steels like CPM154, you will see that the Mf is around -95F.

As the alloying goes up, the Mf goes down.
Basic carbon steels have a Mf between 80F and 200F.
Steels with more alloying, like 52100, may need to drop to near 0F to reach full martensite transformation. Some folks put them in the freezer overnight, but all you need to do is get them to that temp for a minute or two. Then you can warm them back up to room temp and stick them in the tempering oven.
Stainless steels need around -100F.
Cryo at -400F will create the conditions for eta carbides to form during the temper. This adds 1-2 hardness points.
 
Thanks for the informative replies.

I did make some extra file guides using the left over supposedly CPM154. I never RH tested them after plate quenching. I just dropped them in the DI bath. They tested RH 40 also after the DI bath. So I'm still wondering what the heck happened here. I'm at a loss.

I still say the steel I bought was not CPM 154. I know I've read similar threads in the past and ALWAYS doubted it was the wrong steel. But I 100% know the steel I made blanks and heat treated was labeled CPM 154 from a reputable supplier and it acts nothing like it according to any sources I check on.

In retrospect I can't imagine not having a Rock Well hardness tester to VERIFY what you are producing as a knife maker. Years past I would have just assumed according to "theory" and "recipes" I was producing a knife heat treated to perfection.
 
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You're using the wrong foil. It's useless at those temps so you probably have a thick layer of decarb. Grind it off and retest.
The dry ice/cryo isn't necessary to get a hard blade. You should still be around 59 rc after temper without it or about 61rc with it.
 
1950 @ 30 minutes, temper 2 hours at 400 3x, Rc = 60.0. Been my recipe for 15+ years and it's worked every time for me. Never used dry ice nor cryo. I make sure to use the high temp foil as others have suggested. Have no way of knowing if you do or not.
Best of luck.
 
While the Mf90 point (over 90% of austenite are transformed to martensite) of CPM154 might be around sub zero temperature. It is pretty much not the case with these 40RC as queched problem... All stainless steel has Mf90 below 0F included 440c. This might be due to the wrong steel or decarb.
 
As I stated in my OP I did use lower temp foil wrap. Admittedly the low temp foil. yes it stuck to small parts on my bevels but otherwise OK. I'm talking several pimple size marks on bevels. I cleaned just like I always do when heat treating 440C then I tested. No decarb only heat temp shadows exactly like 440C that I've successfully heat treated. So no decarb. I actually made some file guards with left over CPM 154 material and instead of testing put immediately after heat treat put in DI bath. Didn't matter they two tested RH 40 Just to

I've threads in past people received wrong steel. I thought they was off on a tangent. But now I'm a believer.
 
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Low temp foil shouldn't have been an issue, unless it was particularly low quality foil. I've been using the low temp "precision brand" toolwrap foil at 1975 for my stainless for the last 30 or so knives with great results.
 
I only buy Steels from three different Suppliers, Aldo at NJSB, Crucible, and once in a while, Trugrit. I mostly buy belts from the last.. I don’t own a RC tester and have my full sheet or two purchases go from Aldo to Jay my water jet man at, Waterjet Tech, which are cut to my patterns, then to PAUL Bos wherevmy blades are HTed and RC tested to my specs and then to me...—-///—///——————————————— I’ve seen a few struggle with Steels they bought on eBay etc and I use to get some stuff from Jantz, it only takes one gal or guy absent Mindedly grabbing the steel from the next bin over to make things a mess! .. The wrong steel can cost a heck of a lot more than the cost of the billet/Bar. I hope you get to the cause of this problem because CM-154 is an excellent steel!
 
If it clearly appears to be the wrong steel, contact the seller and ask if he would have the smaller pieces, or the blade, tested to see what alloy it is.
 
I just today called the supplier just to see if they had received any other complaints or problems similar to mine. Of course they said they hadn't and truthfully I believe them.

Because I was using the lower grade foil when I tried at a higher temp of 1950F it was a epic failure and the foil stuck to the entire blades on both sides. I just tossed them. The only thing I have left of this steel is some file guides that didn't harden either. I don't believe it would be cost effective to spend anymore time or money on finding out exactly what metal I was sent. I guess it's just another one of those lessons learned in life.

On another note can any one recommend a place to purchase the higher grade foil at a reasonable price? Thanks for all the replies
 
I used to buy high temp foil from tru grit before switching to low temp from my machine shop supplier here in Canada. Tru grit was quite cheap from what I remember.
 
I would ship the hardened file guides to the seller and have them test the steel. All the problems you had in HT aren't the cause of a Rc40 hardness.
Before you do that, I would grind the heck out of them and re-test the steel after removing 1/16" of the surface. Maybe there is hard steel under the decarb.
 
Quote " Before you do that, I would grind the heck out of them and re test the steel" LOL Great minds think alike but I don't have a great mind. I DID THAT just this evening. Picked up a couple points on my recently double checked RH tester. Reading says 47. This is from oven to aluminum plate straights to DI slurry! NO TEMPER! I have no idea what happened. I'm pretty dang confident my equip is dead nuts on from oven to RH tester. I just can't find any steel data formula's that would give me the results I ended up with.

I'll be the first to admit when I make a mistake. Believe me I know I make mistakes. But I'm 99.99% confident in my HT equip and testing results. I don't think I failed in my results with the exception of using lower temp SS foil wrap but it still did give me acceptable performance at 1935F temps!
 
Do you have any ferric chloride or even warm or hot vinegar? I would try a quick etch test and see what happens. That should help tell you at least if it’s a stainless or not.
 
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