1084 grain size?

Sando

Sando

Knife Maker
Joined
Jul 4, 2002
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[back to the saga of a tough kids knife...]

I picked up some 1084 (17hrc as delivered) from Pops. I wasn't happy with the grain size I was getting (no forging). So I compared it with a 1075 coupon (28 hrc as delivered).

Check this out:

IMG_7089.jpeg

Top is 1075 (heated to 1475, 10 minutes - 64hrc)
Middle is 1084 (1525 normalize, 1365 DET anneal, 1485 10 minutes , 66hrc)
Bottom is 1084 (1470, 10 minutes, 65hrc)

As you can see the 1084 grain size is just not good. The lower temp grain is a bit better. But both 1084 samples were pretty easy to snap. I had to score the 1075 sample to get it to snap.

I don't know if there's anything else I can do to help the 1084.
 
Not a problem, Steve, though it will take you a couple of extra heat cycles to do "grain reduction through thermal cycling".
There's an article on Larrin's knifesteelnerds titled "How to Thermal Cycle Knife Steel." A google will get you there. It'll tell you what to do. I'd link it, but it has a subscribe button on the page, so...
 
fitzo said:
Not a problem, Steve, though it will take you a couple of extra heat cycles to do "grain reduction through thermal cycling".
There's an article on Larrin's knifesteelnerds titled "How to Thermal Cycle Knife Steel." A google will get you there. It'll tell you what to do. I'd link it, but it has a subscribe button on the page, so...
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Thanks Mike.

Actually that is the process I used for the middle sample. I got it from the page you mentioned. It didn't help.

But because it's you, I'll rerun the test. ;)
 
So, you are saying you did a couple of critical-temp heats you didn't mention and let it air cool before the anneal? ;)
You can get grain size down to almost where it won't harden with 1084, Steve. There are old archived discussions of this with Cashen here on Bladeforums and at KnifeDogs. Maybe reading something in those will trigger an idea for you.
 
fitzo said:
So, you are saying you did a couple of critical-temp heats you didn't mention and let it air cool before the anneal? ;)
You can get grain size down to almost where it won't harden with 1084, Steve. There are old archived discussions of this with Cashen here on Bladeforums and at KnifeDogs. Maybe reading something in those will trigger an idea for you.
Click to expand...

Yeah, buddy I did mention it but in short hand. Sorry about that. Here's a longer version for the middle sample:

Step 1 - Normalize: Heat to 1525, hold for 15 minutes, air cool
Step 2 - DET Anneal: Heat to 1365 (sub-critical), hold for 25 minutes, then cool to 1100 at a rate of 600/hr
Step 3 - Harden: Heat to 1485, hold for 10 minutes, quench in Parks 50 at 110 degrees.

When we get steel that's already fully annealed, I'm not sure steps 1 and 2 are useful. That's why I did another sample with just Step 3, but it wasn't much different.
 
I guess I got the shorthand okay, Steve. The part I'm speaking of is a couple of grain-size reduction cycles in between the normalization and DET anneal wherein you heat the steel to about 1450F and allow to air cool, cycling down in grain size each cycle.
 
fitzo said:
I guess I got the shorthand okay, Steve. The part I'm speaking of is a couple of grain-size reduction cycles in between the normalization and DET anneal wherein you heat the steel to about 1450F and allow to air cool, cycling down in grain size each cycle.
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I did another one:

Step 1 - Normalize: Heat to 1525, hold for 15 minutes, air cool
Step 1.1 - Normalize: Heat to 1525, hold for 15 minutes, air cool (Second one)
Step 2 - DET Anneal: Heat to 1365 (sub-critical), hold for 25 minutes, then cool to 1100 at a rate of 600/hr
Step 3 - Harden: Heat to 1485, hold for 10 minutes, quench in Parks 50 at 110 degrees.

The results were the same - uninspiring grain size.

You know most of the stuff I read talks about recovering grain size after forging. The thermo cycling you mentioned is always in context of forging. But I'm starting with a super soft, annealed, 17hrc steel.

Both my test bars are fulled annealed (but from different suppliers). The 1075 vendor A, heat/quench is silky smooth. The 1084 vendor B, heat/quench is coarse.

Both vendors say no pre-steps are needed.

:rolleyes:
 
That super-soft, annealed 1084 steel doesn't mean it wasn't rolled way too hot at the factory, growing larger and larger grains, and the anneal simply softened huge grain. That is some really, really fugly-large grain. Forged stuff is that ugly when heated too much, too high, also. It may need more cycles a little lower temp than you've given it so far, coming from that large.

Or, maybe try Fowlers' old "triple-quench" style and re-harden several times. That apparently reduced grain size in his 52100. (Never thought I'd suggest this. :) )

Interesting issue. Given what I've seen during my time when I was bladesmithing, it's hard to imagine that steel can't be recovered if it actually is what it is named.

Maybe Devin or Larrin may have an idea or three. Good luck with it, Steve.
 
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While Devin and Larrin might chime in here hopefully, this is what I recommend personally...

I am pretty sure that is NJSB 1084 even tho you bought it from Pop's. Don't quote me, but I am pretty sure. That stuff comes sort of heavily spheroidized from Buderus, and a normalizing heat of 1525°F is too low.

Try 1650°F for 10 minute soak and air cool. This is pretty much an industry standard normalizing heat for 1084 (1600-1650) and now you know what condition the steel is in. Coarse carbides broken up, carbon ready to go into solution, even grain size.
Cycle at 1500°F twice, air cool for grain refinement after the higher normalizing heat
DET anneal
1475°F soak for 5 minutes, fast oil quench.

I hope that helps.
 
Stuart Davenport Knives said:
While Devin and Larrin might chime in here hopefully, this is what I recommend personally...

I am pretty sure that is NJSB 1084 even tho you bought it from Pop's. Don't quote me, but I am pretty sure. That stuff comes sort of heavily spheroidized from Buderus, and a normalizing heat of 1525°F is too low.

Try 1650°F for 10 minute soak and air cool. This is pretty much an industry standard normalizing heat for 1084 (1600-1650) and now you know what condition the steel is in. Coarse carbides broken up, carbon ready to go into solution, even grain size.
Cycle at 1500°F twice, air cool for grain refinement after the higher normalizing heat
DET anneal
1475°F soak for 5 minutes, fast oil quench.

I hope that helps.
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Thanks! I'm on it. Oven is busy right now, but I'll give it a try ASAP.

Man! it's so important to run tests when you get some new steel.
 
Steve, I am glad you are getting help from someone who knows the modern state of steels for knife making. I know I am out of date and try to stay out of HT threads, but no one answered for a while and old habits took over. :( Heck, it was someone I actually knew! :) Sorry I couldn't help.
Hope your trial with Stuart's recommendations works great for you.
 
Annealing doesn’t always refine the grain. It requires some cycling at 1450’ to refine the grain, after normalizing.

Kevin Cashen has an in-depth DVD on 1080/1084, well worth the money.

Hoss
 
Thanks for the idea fitzo fitzo !

Well Stuart Davenport Knives Stuart Davenport Knives . It helped for sure, but still not there. I used the recipe exactly as you described (my oven seems accurate).

Here's what I got:

IMG_7092.jpeg

Left is where I started with this 1084. Center I used this:

1. 1650 10 minutes, air cool
2. 1500 10 minutes, air cool
3. 1500 10 minutes, air cool
4. 1365 25 minutes, cool to 1100 at 600DPH
5. 1475 5 minutes, quench in Parks 50 110f
Tested at 66hrc

On the right is 1075 from AKS, that was just heated and quenched.

FWIW this is Pop's choice 1084 that came from Sheffield.
 
I agree with Stuart that it's probably in a spheroidized state. I have found that I have to use even higher temps ie 1750 initially. I went through a similar problem with W2 a few years ago and found that I almost had to heat it up to forge temps to break everything up.
 
Can you give the dimensions of the pieces in the picture?
 
Don't heat Parks 50 up. I think 110°F is just within the upper range if memory serves. Use it at room temp or a bit warmer.

As mentioned, you can try 1700°F for the initial normalizing heat, and that I think it probably good advice being that it is almost certain this came from the Buderus mill that is notorious for very soft (coarsely spheroidized) carbon steel.

Usually I do 3 thermal cycles after a high normalizing heat. If I bought 1084 my process would resemble something like
1700°F 20 minutes normalizing heat, air cool
1500°F 10 minutes thermal cycle, air cool
1475°F 7 minutes thermal cycle, air cool
1450°F 5 minutes thermal cycle, air cool
DET anneal
1475°F, 5 minute soak, P50 quench
 
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Hey guys, I was up at Pops this weekend and we looked into this and confirmed some of the grain issues and they have already reached out to the supplier who is reaching out to the mill to see what can be done and where things went wrong. It should have been in a good condition to go straight into hardening, Pops has pulled the steel from their site until a resolution has been reached and asked me to post here on their behalf to let everyone know they are doing what they can to make this right and are happy to work with people who picked up some of this steel. They also gave me a couple bars to take back to my shop and do some more testing to come up with a good schedule for the material already on the market. I’ll be sure to post back here with updates.
 
Joshua Fisher said:
Hey guys, I was up at Pops this weekend and we looked into this and confirmed some of the grain issues and they have already reached out to the supplier who is reaching out to the mill to see what can be done and where things went wrong. It should have been in a good condition to go straight into hardening, Pops has pulled the steel from their site until a resolution has been reached and asked me to post here on their behalf to let everyone know they are doing what they can to make this right and are happy to work with people who picked up some of this steel. They also gave me a couple bars to take back to my shop and do some more testing to come up with a good schedule for the material already on the market. I’ll be sure to post back here with updates.
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Thanks for checking in on that Joshua Fisher Joshua Fisher . I should have contacted them myself, but I assumed it was all on my side. Pops is a great place and love doing business with them.

FWIW I also tried Robert Erickson Robert Erickson 's idea and heated to forge temperature.

2000 30 minutes, oven cool to 1400, then air
1525 25 minutes, air cool
1365 15 minutes and slow cool.
1475 10 minutes, quench

It looked the same.
 
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