Help with Heat treat problem, alloy banding in stainless?????**PIC ADDED

[Wolf Creek Forge]

Well I did some testing and everything came out good except that I heat treated a batch of blades and almost all of them seem to have "alloy banding" but they are A2,D2 and 154cm All wrapped in foil, followed the heat treat precisly, followed by a sub zero quench and tempers..Looked great out of treatment..Most grey/white with only small ammounts of color but after grinding back to about 320 grit they all still have a mottled pattern..Ive took off more than enough to remove any decard..It looks just like the alloy banding Ive seen in some 1095 but I wasnt aware it could be a problem in high alloy steels..Would a stress relieving cycle and re-heat treat fix it? What do I need to do to avoid it? Just what did I do wrong? One normalization not enough?
Just for instance my A2 heat treat was 10 minute soak @1475, ramp to 1800 soak for 30 minutes, plate quench and then into the aub zero quench..Was the soak not long enough? The 154cm had a 45 minute soak and the "banding" was less pronounced with it...
Ok, Ive added a pic here..if you look close you can see a grainy appearance on this A2 blade..This is machine finished to about 240 grit(appx) Its less noticable on one of the 154cm blades but downright awful on the D2 blade..

 

[james terrio]

Ahh, the dreaded orange peel look. There's a reason nobody bothers with a fine finish on D2 - it looks worse and worse the more you polish it.

It sounds to me more like alloy "clumping" than banding. I've seem this in poor-quality 440C and 154CM, and D2 is famous for it. I can't say about A2, haven't used any yet.

If you like 154CM and D2, pay a few extra bucks and get you some CPM-154 or CPM-D2. They have the same basic chemistry, but the "powder" type process by which they're made means they have finer grain and smaller, more evenly-distributed carbides. This means they sharpen and polish up much nicer and are also a little tougher.

 

[Wolf Creek Forge]

Thanks, we really took our time and followed these heat treats to the letter..Im puzzled? At first I was wondering if i got a good seal on the foil packs but I hammered them shut..Its pretty frustrating..

 

[mete]

You're still dependant on the steel maker and if it's someone like China lots of luck ! James has the answer , spend a little more on the steel and save yourself problems.

 

[Wolf Creek Forge]

You're still dependant on the steel maker and if it's someone like China lots of luck ! James has the answer , spend a little more on the steel and save yourself problems.

How will this effect the blades? will it be of any use to reheat treat? and thanks for the time..

 

[Stacy E. Apelt - Bladesmith]

When the carbides don't get fully into solution, this can occur. The answer is one of two choices:
1) Make sure the austenite soaks long enough and hot enough to fully dissolve and distribute the carbide formers. Depending on the condition of the steel pre-HTR, this may or may not eliminate orange peel.
2) Buy CPM steel and don't worry about it. The CPM steel has the alloying locked into microscopic balls of evenly alloyed steel. These are fused together, but the boundary of each sphere is pretty much impermeable to the carbides wandering around. This means the end product is pretty much the same distribution of alloying as the starter bar was.

 

[Wolf Creek Forge]

Well, Ive decided to reheat treat and try a longer soak time..I dont think it can hurt, I have them on a two hour stress relief cycle right now..So we shall see..

 

[Justin King]

I have run into this problem repeatedly with both A-2 and CPM154. I didn't think it would be a problem in CPM material but I have seen it in 2 or 3 seperate bars of the 154. I have more or less quit using both, for that reason as well as others.

 

[Wolf Creek Forge]

Justin, I re-heat treated these blanks and they came out the same as before..The only think I did different was to soak them at aust temp a bit longer just to make sure..The steel itself seems just fine with testing, grain and edge look fine but that orange peel grainy texture looks like crap..
I want you guys to know that I went back to the original bars and cleaned up about a 2" section. The bars themselves, before heat treat have the same orange peel grainy texture pre-heat treat as they did post-heat treat,,This leads me to believe my heat treat was fine and it was in the steel all along..What do you all think?

 

[Justin King]

Justin, I re-heat treated these blanks and they came out the same as before..The only think I did different was to soak them at aust temp a bit longer just to make sure..The steel itself seems just fine with testing, grain and edge look fine but that orange peel grainy texture looks like crap..
I want you guys to know that I went back to the original bars and cleaned up about a 2" section. The bars themselves, before heat treat have the same orange peel grainy texture pre-heat treat as they did post-heat treat,,This leads me to believe my heat treat was fine and it was in the steel all along..What do you all think?

I found that the banding pattern is evident in the bar from the supplier also, your conclusions pretty much mirror my own. I did not find any performance deficiencies related to this issue but the finishing problem itself is enough. A stonewashed finish will hide it but any other finish just looks terrible. I bead blasted one of my CPM154 blades that had this issue and the banding was unaffected by the media, showing as shiny spots in the matte finish when I was done.

 

[james terrio]

...will it be of any use to reheat treat? ...

No. The problem is literally embedded in the steel. Nothing you can do will "fix" it.

I have run into this problem repeatedly with both A-2 and CPM154.

I'm shocked to hear this. Are you certain that you're dealing with CPM-154 and not 154CM? That should absolutely not happen with any genuine Crucible CPM steel. If I were you, I would have a very loud discussion with my steel vendor. :grumpy:

 

[Justin King]

I'm shocked to hear this. Are you certain that you're dealing with CPM-154 and not 154CM? That should absolutely not happen with any genuine Crucible CPM steel. If I were you, I would have a very loud discussion with my steel vendor. :grumpy:

In the case of the CPM154 I did speak to the vendor, it is certainly possible that the steel was mislabeled but the banding was present in 2 bars ordered seperately, over a year apart. I have never bought or used the 154CM (the non-cpm variety) so there is no chance of getting the 2 mixed up in my shop.

 

[james terrio]

In the case of the CPM154 I did speak to the vendor, it is certainly possible that the steel was mislabeled but the banding was present in 2 bars ordered seperately, over a year apart. I have never bought or used the 154CM (the non-cpm variety) so there is no chance of getting the 2 mixed up in my shop.

Get on the phone right now and kick some... y'know. There is something seriously wrong with that situation.

 

[Wolf Creek Forge]

One last update..We tested two of the blades to destruction, including the one in the pic..Both had very nice fine grain, both very tough..So I was actually happy with the heat treat but like everyone suspected it is just a flaw in the finish..The D2 blade looks like a 3-day in the sun orange:grumpy: The 154cm isnt so bad and is hard to notice unless you really look for it by turning in the right light..I think with the right finish it will be just fine..
Thanks for all the help..

 

[james terrio]

...I think with the right finish it will be just fine...

The "right" finish for those blades is a coarse machine/belt finish, tumbling/blasting, or powder-coat. Basically, whatever hides the fact that the steel just isn't very good... certainly not as good as it could be.

 

[Justin King]

Get on the phone right now and kick some... y'know. There is something seriously wrong with that situation.

I agree completely, but my supplier didn't make the steel himself, so any posterior kicking should rightly be reserved for NSM.

This happened a while back and just confirmed the way I have felt about stainless most of my life- that it dosen't really have a place in my shop, CPM or not. I wasn't hugely fond of A-2 as an end product either, I mostly used it for prototypes.

 

[james terrio]

WARNING: completely off-topic post.

This happened a while back and just confirmed the way I have felt about stainless most of my life- that it dosen't really have a place in my shop, CPM or not. I wasn't hugely fond of A-2 as an end product either, I mostly used it for prototypes.

Whether or not you choose to utilize various alloys is of course, entirely up to you.

However... It is wrong-headed, ignorant, unfair and just plain dumb to write off/ignore an entire class of excellent alloys, just because some unprofessional vendor (or his minimum-wage warehouse/shipping flunky) mislabeled a couple bars (and I'll bet my lunch, that's what happened to Justin). I've gotten mislabeled steel before, too... I no longer do business with those firms. I certainly do not disparage an alloy because of their foul-up.

I'm not attacking JK by any means; I'm only posting this because for years down the road, people who are researching good steel will find this thread.

 

[Wolf Creek Forge]

The "right" finish for those blades is a coarse machine/belt finish, tumbling/blasting, or powder-coat. Basically, whatever hides the fact that the steel just isn't very good... certainly not as good as it could be.

Do you mean "good" as in cosmetically, or "good" as in performace?

 

[Stacy E. Apelt - Bladesmith]

Good as in cosmetically. I don't think it will really affect the cutting ability or strength of the knife.

 

[james terrio]

Do you mean "good" as in cosmetically, or "good" as in performace?

Cosmetically, mostly.

An alloy with the same chemistry but better manufacturing will have a finer structure, and that means sharper edges and probably higher toughness. Ignoring appearances, would the average knife-user be able to tell the difference between CPM-154 and 154CM in use? Probably not.