Big Problem HT'ing Damascus -

R

rlinger

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Mar 29, 2002
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Am making a knife using Thunderforged damascus. It is 1095 and O1 with 8 percent nickel.

Before heat treating the blade I thought it wise to experiment with some sample pieces. I have gone round and round trying to get it where I want and can not get above about 53 HRc!! I have heated at 1450 F., 1465 F., 1475 F., 1490 F., and 1520 F.. I have soaked from 2 minutes to 40 minutes. I have quenched in oil and I have quenched in brine. I have double quenched and I have single quenched. I have tryed five different sample pieces from the same stock and in varying sizes. I have ground off decarb to both course and smooth finish. No matter what I try they always test at a low of about 50 and a high of about 53 HRc. I have tested them on two different Rockwell testers. Both testers tell the same and track each other to within 0.5 HRc, and I have tested them against my standards to be sure they are not off.

I am beginning to wonder if it is the nature of damascus that may be causing me to get false readings.

EDIT: I forgot: I even broke out the propane torch and heated one piece to non-magnetic. It read the same.

All my tempering has been at 350 F. and for 1 hour. All testing is done after tempering and all samples were tempered only once before testing.

PLEASE ADVISE.

Roger
 
Very tough to get decent rockwells on damascus, Roger. The steel is too non-homogeneous. Doing the brass rod and some cutting tests on the blade is about best you can do. However, if you can't hit any high hardness spots at all I'd be a bit worried about the steel itself. Do they inform you of the composition? I'd personally not temper and check your hardness right out of quench. then start at about 250 and work my way up on sequential tempers, depending on where it stood.
 
possibly cool your quench medium down some (not the oil) i have read on another forum that a brine quench or straight water quench might be better for that particular damascus, i have no practical expierence with that steel however. i have also heard that that brand of damascus isn't quite up to par with some others.
 
Thanks Fitz,

I tested various areas of the samples. Some areas would measure alittle lower or higher but none higher than about 53 HRc (I may have got a 55 at one time). Thanks for the input.

I prefer not to try a Rockwell test on 'as quenched' steels. That could be dangerous.

Roger
 
You should be able to rockwell "as quenched" if you choose a wide spot for the diamond. It should read about 63. There is no sense tempering the blade if you arent sure of full hardness.

Ive had trouble with their damascus warping due to improper normalizing. Try a couple more pieces and normalize first just for another hardness test. The nickel content may be the culprit too.

As already mentioned the brass rod test is better than a rockwell test on nickel damascus.
 
Do some performance testing on a heat treated and tempered blade. Or do like some of us hardheads and forge up your own damascus. Bill Moran uses 01 and 1018 for his damascus and he says there's no need to draw a temper on it. Just use it 'as quenched'. And you can't argue with his success either. Maybe I'm just a knothead, but I've never used any Rockwell testers on any of my blades. The file test and my experience with steel is all I use to judge hardness and toughness. Of course, there's nothing like duct taping on a handle and flailing some 2X4's or local underbrush to test an edge when you're not sure about the heat treat. There's lots of knot holes in my woodpile most of the time and a knot hole will really put the acid test to your blades. Have fun and if it don't test too good on the Rockwell scale, just head for the woodpile for a real test. :D
 
I have forged a few blades out of Thunderforge and brought them up to nonmagnetic and quenched them in 140F oil. I tempered at 400F three times and each knife has done well...all passing the the brass rod flex test.

Could be that the nickel in the mix is not giving a homogenous reading on the tester?
 
Okay, I'll go ahead and cut another 'fresh' sample piece and, as suggested by Bruce Bump, normalize first. This stuff is real tight and is difficult to find a blank spot to test.

I really prefer to get a feel for the HRc on this stuff before actually treating the blade. The only thing is until I figure it out I'm stuck just spinning my wheels because the HT is the next step in making this knife.

I'll let you know, here, how my next test goes.

Thanks.

Roger
 
Hey, Roger,

I've been testing as-quenched steels with a tester for years and never had any problems. I am a science geek and always wanted to know what hardness I was getting at every step of the HT process. It isn't uncommon for me to do 15-20 indentations at different steps. I also used to test alot of tungsten carbides and ceramic cutting tools with hardnesses in excess of 90 and never had a piece or the tester break.

I guess I'm saying I don't think you'll have a problem seeing what the Rockwell is at full hard, though getting an accurate reading on damascus is almost impossible. There should oughtta be some one area, though, when yer doing multiple indents, that should give a rockwell in excess of 60. I've done it often enough on my own damascus here. Expect a HUGE spread of values, though, especially if there's nickel in the mix.

I wouldn't bother with too many more tests without contacting the vendor. I'm sure they make decent steel for the most part, but production operations do have a certain "failure rate" that makes it to the public, sometimes inadvertantly, sometimes not.

If you've done the tests several times, I'd start suspecting the steel.
 
Fitzo,

I just tested a piece that I equalized first. It tested HRc 52. I tested it in three different areas. I got two at 52 and one at 50. I am now normalizing a piece. I'll HT and Rockwell it too. If nothing dramatic changes in testing, that will be my last Rockwell test on this damascus.

I am rapidly becoming aware that because of the nickel mix I am not going to get a good static test. I am just about convinced that the only way to tell is to make the knife and test it dynamically. My temp's and times are solid for 1095/O1 and I have covered the window on heat treating it.

I'll check this last sample and after that I'll just heat treat the blade the way I otherwise think it should be done; the way I'd do it without preliminary Rockwell testing. Then I'll put it to the seasoned oak. There will be little doubt after that. DAMN - still won't know the number though. I hate that.

Roger
 
A couple things come to my mind and one is it could have been trashed before you got it. Made with to hot of a temperture. Something else I just heard or read is 1095 needs to go from the fire to the quench in one second or it doesn't reach it maximum hardenss.

I know this is pretty frustrating, I've had a few simular problems myself.....
 
Ray, No problem on the one second thing. I continuously practice at that. Well, (big sigh) I've normalized, I've equalized. I've austinitized and temperized. The only-est thing I've not done is deep cryo. What's the use. I have also, on the last sample, tested 'as quenched'. It has become my humble determination the nickel content will not permit a determinative static test. Therefore, I shall heat treat and cryo the blade as I otherwise would without prior testing, edge it and test it on cardboard and seasoned oak. Thanks to all for your help.

I will report back on my results.

Roger
 
I would think seriously about the possibilty that the steel suffered decarb during its making in India. Sounds like either that or quench time. Either way I would try a very fast water quench.

Daniel
 
Daniel,

May well be. The steel is paid for, the blade is profiled and I'm grinding and HT'ing tomorrow. I won't waste the ivory on it unless it passes. What the hell - I've never beveled damascus before. This might turn out well. If it does not I'll ask someone here to sell me a good piece for this Euopean Cave Bear fang handle.

Here is how I plan to HT:

Equalize at 1200 F./7 minutes, 1490 F./5 minutes, 140 F. oil quench/approx. 7 seconds, snap temper at 325 F./1 hour 10 minutes, deep cryo 12 to 18 hours, temper at 375 F., double temper at 350 F.. I may decide to change the hardening temperature from 1490 to 1500 because of the 1095 and normally I would austinitize O1 at 1465 to 1480, so I'll up it a bit because of the 1095. I may also decide to move my draw temperatures up 25 degrees. Whatever, if my testing turns out worthy I will post the true HT specs here.
 
Rodger
I'm thinking, that the layers are thin and you have nickel
beneath, you'll have a flex that will give you a faults reading
on the rock test.
like trying to test thin steel laying on
rubber :confused:
1095 in oil works for me 1085 is not so good.
I think the layered nickel is your culprit for a faults test
if you can heat treat o1 and 1095 other-wise with no problem..
cutting test are in order...and the flex:D
 
Dan (Gray), I think I have finally given in to what you suggest. I, at least, hope that is the problem. This steel is SOOOOO pretty I hate it not to work well. Your assumption, no doubt based on experience, is what I am banking on now. I have no other direction to hope for.

I will share my results here. It will take a couple/three days.
 
Roger. harden it (make sure its non-magnetic and quench if fast and hard.) Temper it (to a temperature on the low side in a reliable oven that you know works). then test it dynamically. (great choice of words!)You can always come back and temper to a higher temp if its too hard. MAX is right. I am a firm believer at flailing the underbrush, chopping oak pallet lmber, cutting carboard, to test. the edge geometry has soooo much to do with the practical usability of a blade that its hard to rely on a RC number alone. A blade that has been tested, and perhaps is cosmetically lacking, is of greater value than a blade that is perfect but untested. I can tell right off if a blade is ablout right for its individual geometry by the way the oil stone cuts it.
 
Fox,

Your post is well timed as I was about to update (change) my intentions for heat treating this blade, here. I have decided there will be no computer controlled oven used for this blade, except for tempering. Instead of doing it as I outlined above I will do as Tim Zowada taught me to heat treat tool steels. I will brake out the propane forge, turn all lights off, draw the blinds and look for the shadows to dissapear. It is only proper that I do it that way for my very first damascus knife. In view of your tempering advise I shall drop my draw by 25 degrees from that I above specified. If she chips I'll re-temper at an adjusted level.

Thank you.

Roger
 
Hey, Roger!

I didn't know Tim Z. taught you! Cool. He taught me back in about 1987. Nice guy, Nanc and I spent several long weekends with Tim and Bonnie.

Good luck with that blade!!
 
Hey Fitzo, he taught me that over the phone. I haven't been able to meet him yet. He's The Man, ya know. In fact if we decide on damascus for the collaboration hunter I'll be calling him again.

Roger
 
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