Problem heat treating

[SVanderkolff]

I am attempting to heat treat a blade of damascus, composition is 1095 and 15n20. I took the blade to 1450 and oil quenched but when I tested the blade it was only coming in at 42 rockwell. So I figured maybe I didn't soak it long enough, so I stuck the blade back in the kiln and again brought it to 1450 , then let it soak at between 1440 and 1460 for about 20 minutes, again immidiately quenched in oil. I tested it again and it was still registering 42 Rockwell. I then tested the tester with my calibaration black and it was fine.
So a couple of questions.
Any suggestions as to what is happeninghere?
Do I need to anneal the blade before I heat treat again?
Should I try taking the blade to 1500, just in case my thermometer in the kiln is off?

Your help is greatly appreciated.
Steve

[Ray Rogers]

I usually use 1475 for 1095 but I don't think that's your problem. Maybe you just skipped telling us the details but you didn't mention cleaning and surface grinding that chunk of damascus after the heat treat.

Doing a Rockwell test on damascus is a notoriously fruitless persuit. Due to the nature of damascus you can never get truly reliable results. If if fact you haven't cleaned the bar to the point where the sides are clean, smooth, and parallel that alone would virtually guarantee inaccurate results.

Try breaking a piece of the steel to see if it is properly brittle if you can spare some, or use a fresh file on it. With 1095 and 15N20 a fresh file will probably skate off the damascus fairly well although a file will often cut hard damascus more easily than it might cut a homogeneous hardened steel.

In short, make a blade and test it to see if it performs as it should. Mechanical hardness testers aren't reliable on most pattern welded steel....

[Ed Caffrey]

I suspect that the 1095 is the problem. Over the past couple of years I have recieved far too many emails and phone calls with similar probelms to yours. My advice? Get rid of the 1095! It has no place in my shop anymore. Every since the specs have widened on 1095, it is at best a hit and miss proposition. Some batches harden easily, and other batches are impossilbe to harden. Without getting too long winded, suffice to say that because of the widened tolerances, some batches give you less than one second on the Time/Temp curve.....making it impossilbe to harden. It has become one of those steels that require you to "reinvent the wheel" each time you get a new batch, and it just ain't worth the heartache.

[Robert Washburn]

You mite want to try water quinceing it. Robert

[Matt Walker]

Steve .. I don't claim to know much about heat treating, but I have friends that do. I consulted one of them today about your problem. What he said was almost exactly what Ed said above about the nose on the time/temp curve and the spec. range on 1095. In his case he was making flint strikers from some 1095 and had to use a fast water quench to get them hard enough to make good sparks. Good luck and let us know if/how you work it out.
Matt...

[SVanderkolff]

Thanks all.
I used all of the above suggestions. I first annealled the piece, then I reheated it to 1475 then I water quenched it. I don't which one worked but I end up with a consistent 66 rockwell before tempering.
Once again the collective wisdom of the group triumphs over the vagracies of the steel.
Thansk
Steve