Need Help Identifying Steels

O

Oliver Sommer

Basic Member
Joined
Nov 21, 2024
Messages
10
For a While now I have been trying to find a "cheap" way to make Damascus. at one point I had been given a bunch of old bandsaw blades from a portable wood bandsaw mill. I then got some worn out ones from the local steel suppliers metal bandsaw. I hand forging the billets, but I always had delamination problems. Once I got my press working, I decided to give it another try, I got a solid weld and was able to forge a blade. When I tried to anneal it I realized that it was some form of air harden. I got the knife ground down and hardened it in the air and clamped in my vise. I Rockwell tested it and got 63rc in one place and 60rc in two other places. There is surprisingly good contrast for being mystery steel. I'm hoping that someone would have an idea of what steel it could be. I'm thinking that the bright steel could be L6 and the dark D2. If anyone has any experience with bandsaw Damascus or air harden steels, that would be great.image0 (2).jpegimage0 (3).jpeg
 
DevinT said:
The metal cutting bandsaw blade is most likely high speed steel.

The wood cutting blade is probably 15n20.

Hoss
Click to expand...
Do you know what a spark test would look like for high speed? I've got some 15n20 to spark, but are there any special properties to high speed?
 
High speed steel is usually darker orange and straighter sparks than carbon steel.

However, I don’t think these two steels should be used together, the heat treating is too different.

Hoss
 
I did a spark test against a piece of high-speed milling bit, and the sparks were entirely different. The other one matched perfectly with a piece of known 15n20.
 
High speed steel heat treats at >2100’f, 15N20 heat treats at ~1450’f, there is a steep drop in toughness for 15n20 if heat treated over 1500’f.

There is a chance that only the teeth are high speed steel on the metal cutting blade. Polish and etch a small piece and see what it looks like.

Hoss
 
Devin is getting at what I was saying.
A metal cutting bandsaw blade may be many types of steel. Some are just alloy steel with hardened teeth, others bi-metal with a soft backing and HSS teeth, some are all HSS, etc.
And then, what type of HSS? HSS is a term, not a specific alloy. Is it M1, M2, M7, M42, M50, T1, T4, T6, ....etc?
If considering making damascus, HT for HSS is not the same as carbon steel. The two won't play well together in the HT oven.
Point is ... you don't know what it is. It is folly to make a knife when you have no idea if the metal will work or how to HT it. For making damascus, it is even follier ( is tat a word?)
 
I am curious. How did you come about thinking the darker steel is D2? D2 is a semi stainless tool steel? Other carbon steels can air harden as well.
 
I did some spark tests, and an acid etch, which revealed high-speed teeth and a mid-carbon backing. That led me down a rabbit hole of carbon migration. From what I've been able to gather carbon will homogenize through ought the layers. So with 15n20 (about .75% carbon) and the mid carbon (approx. .3-.4% carbon) the carbon should even out around .5-.6% carbon, with the nickel staying where it is. This may not be exactly how it works, but am I on the right path? When I deal with mystery steel I do take extra pieces the test the heat treat process before committing to a larger project. I should also note that I do grind off the HSS after the forge welding. I also tested the Rockwell after air quenching, and it did come back hard.
 
I know your description sounds like that is a reasonable explanation of the process, but you aren't melting two steels in a vat. It isn't like taking 50% FC and adding water to make 25% FC.

Carbon migration is a very misunderstood thing to most knifemakers. It is a process of time and temperature. The time and temperature for making damascus is far too low and short for complete migration. Carbon migration for knifemakers is in microns. Where is shows up is at layer boundaries on stainless cladding. It usually shows as a carbon depleted zone more than a carbon enrichment zone.

Just because it etches bright does not mean it is high-speed steel ... and just because it etches dark, does not mean low/mid carbon steel.
I consider spark tests and etch tests elimination tests , not qualitative tests.
 
You must log in or register to reply here.
Back
Top