Carbon Content of 15N20 ?

R

rlinger

Joined
Mar 29, 2002
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I can't find a thing in my stuff or the net about 15N20. Could it have only about 0.2% carbon as its name hints??

Thanks.

RL
 
Isn't that L-6? I think I have some bandsaw blades (8" wide by .075") marked 15n20.
 
My sheet from Uddeholm lists their stock as:
.75 carbon
2.0 nickle
.40 mang.
.30 si
.02 phos max.
.015 sulf. max
 
Thanks all. All your data seems to pretty much agree.

Terry, I am having difficulty Rockwelling a damascus of 1084 / 15N20. Its all over the place and I know the HT is solid. Could that 1.5 to 2% nickel be causing the trouble?

RL
 
rlinger said:
Thanks all. All your data seems to pretty much agree.

Terry, I am having difficulty Rockwelling a damascus of 1084 / 15N20. Its all over the place and I know the HT is solid. Could that 1.5 to 2% nickel be causing the trouble?

RL
Click to expand...

Sounds like something is off there. I have done some work with the same mix and got a very consistant high hardness as quenched (65hrc), with less than 1 point of deviation. You have a very good mix there. In my book, there is only one that will beat it.
 
In that case it can only be one of two things, I think. The quenching oil is not good for shallow hardening steel (it is Tough-Quench at 122 F) or the tang taper is preventing me from getting a good test.

Any thoughts on the Tough-Quench? As a note of interest; I recently quenched another 1084 / 15N20 in vegie oil with no problems at all testing and as you say my readings were very consistant. I got the Tough-Quench specifically for this particular blade. It is really going to suck if I have to go back to $1 a qt. vegie oil. Please advise.

Thanks again.

RL
 
Hi RL, I quess I'll jump in here. 15N20 should rockwell very close to 1084. I use to make a lot of knives out of straight 15N20 and it is a great performer.
The 1.5 to 2 % nickle dose not make it any softer but makes it tougher, and it gets harder than a file before tempering.

Don Hanson :D
 
If the vegi oil works, why change?
The oil I use was given to me about 8 years ago, (5 gallons).
It works so I keep using it. :D

Don
 
Roger,
I got back a little late here. Something is amiss. The 1084 and 15N20 mix is what I use, and I consistently get good results. The two are a perfect marriage.
 
Don, thanks. I can see that now that I have seen the analysis. There is plenty of carbon there.

Terry, have you used Brownell's Tough-Quench for the 10XX series steels with good results? I am really wondering now about it for shallow hardening steels.

I just can't figure it. I got into quench quick enough and the oil was 122 F. I snap tempered (335 F / 55 min.) at hand warm. The tester is all over the place, from 61 to 51. I know I did the temps and times right. Can it be the quenchant?

Thanks.

Roger
 
primos said:
Roger,
I got back a little late here. Something is amiss. The 1084 and 15N20 mix is what I use, and I consistently get good results. The two are a perfect marriage.
Click to expand...

I agree entirely. L6 works better with oil hardening steels, but 15n20 is an almost perfect mate for 1084. I have also found it to be a very clean and easy to use steel. I would do this mix more myself, if they would just make the stuff in thicker cross sections. I am a big steel sqeezing type of guy and stacking up all those little layers is not my cup of tea. I would have many speicalized uses for 15n20 mixes if it came in 1/2"+ thickness.
 
rlinger said:
In that case it can only be one of two things, I think. The quenching oil is not good for shallow hardening steel (it is Tough-Quench at 122 F) or the tang taper is preventing me from getting a good test.

Any thoughts on the Tough-Quench? As a note of interest; I recently quenched another 1084 / 15N20 in vegie oil with no problems at all testing and as you say my readings were very consistant. I got the Tough-Quench specifically for this particular blade. It is really going to suck if I have to go back to $1 a qt. vegie oil. Please advise.

Thanks again.

RL
Click to expand...

Both of the issues that you mention would be very likely candidates. Tought quench may not wokr so well with such shallow hardening steel. I used Park #50 to the the full hardness results that I mentioned before.

Very slight angles on the test surface will almost void a rockwell reading. For this reason I try to take my readings on the ricasso where the guard will go. I just had a blade, that I was testing for somebody else, refuse to take a reading. The sides of the ricasso were not exactly parallel and that slight angle had my readings all over the map, just as you describe.
 
I am a bit apprehensive to even voice an opinion here, but do you think that it could also be in part, the preparation of the steel prior to quenching? That was the first thing that came to mind for me. How well the hardening phase works depends to a large degree on the condition of the steel prior to that final heat where you hit solid solution. That's a lot more important than whether the quench was 120 degrees, 150 degrees, etc. in my opinion.

In fact, that's true from start to finish. Each step depends on how the internal structure was set up on the preceeding step. Technically, heat treating starts on the first forging heat. Folks always talk about getting a fine grain size, but you seldom hear about first getting an even grain size, an even distribution of carbides in the ferrite matrix, then finally a fine grain size.

I'm just thinking out loud here. I see where the angles would give you fits on the Rockwell testing.

By the way, I know that in the thread on quenches there was some question about Chevron 70 with 10xx steels. I've been using it with 1084 and my 1084/15N20 Damascus and I'm happy with it.

My first experience with the stuff was on a scale-free heat treating demo Mike Williams and I did at one of Uncle Al's meetings. We were comparing two different anti-scale compounds. In all the yacking back and forth we forgot to heat up the quench.

Since it was just a demo we went ahead and quenched at room temperature. I couldn't scratch that blade with a file. I ran up front and asked Al what was in that barrel we'd quenched in. I brought home a few gallons of Chevron 70 that night.
 
Absolutely yes. It is very difficult to find a good spot on a knife blade for reliable testing. This particular blade is tapered through the bolsters and this one was supposed to be. I have found, or noticed, that there has to be some judjment based on experience to compensate a reading. For instance, a slight flat bevel may cause a point high in reading. Anyway, this thing is too far off for even that.

This steel I slowly brought to 1400 F and held for 2 minutes and let still air cool and repeated for a total of 3 times. I then ramped slowly to 1200 F pre-heat and held for 7 minutes then ramped balls to the wall to 1495 F and soaked for 5 minutes then full quenched by or before 1 1/2 second and cut in quench to oil temp. and allowed to cool to hand warm after pulling from oil and placed in pre-heated 335 F snap temper for 55 min..

What blows my mind is that I had tested samples of the bar stock before the blade was grinded and had no problems at all. The only real difference is the quenchant oil is Tough-Quench instead of the original vegie oil and the tang taper.

Thanks fellows.

RL
 
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