Mystery Steel

bladsmth said:
Mike,
The carbon content is .066%, equivalent to 1006 steel ( ignoring all the alloy ingredients). That is very low carbon content. Not enough carbon to form any iron carbides, and thus not enough carbon to harden the steel. Steels below 0.40% ( 40 points) carbon aren't hardenable for knife blades. Most folks draw the line at 50-60 points carbon (.50-.60%). This steel has 1/10 that amount.
Stacy
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Funny what the eyes see sometimes... even with the "not a misprint" I saw 0.66% C. Sorry to have troubled you, Stacy.

Mike
 
You could have weeded that steel out with a quick little spark test. Low carbon throws sparks further from the wheel before they die out. The higher the carbon, the closer to the wheel the sparks burn out. All you need are a few samples of known steel with various carbon contents to compare the sparks to.
 
Tai Goo said:
You could have weeded that steel out with a quick little spark test. Low carbon throws sparks further from the wheel before they die out. The higher the carbon, the closer to the wheel the sparks burn out. All you need are a few samples of known steel with various carbon contents to compare the sparks to.
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What known steels would be good, Tai?

Mike
 
Shop testing of steel is a topic for a different thread, but,in regards to comparing several known steels to an unknown sample -
Just because a steel has a similar spark to another steel does not mean it has a similar alloy content. That would be somewhat like buying a rifle on ebay,and comparing a bullet from that rifle to the bullets from guns in your rack and deciding that the gun the new rifle is a good hunting rifle....because the bullet looks like one of yours.

There are several thousand steel alloys, and maybe only a hundred that will make knives..... and maybe a couple dozen that will make good knives. The only way to know which you have is to get it tested. Just seeing if it will get hard, or make sparks, will not tell you what it is, although it may tell you what it isn't. If this steel had .66% carbon ( instead of .066%), it would have sparked like several steels ( 5160, 1070, O-1, who knows what else?), but with the other alloy ingredients, it would probably make a poor blade steel.

The learning point to be taken from this thread is to show that just because someone says it is good steel, and it looks like good steel, doesn't mean it is good steel.


Stacy
 
Mike, I think 1095 or O1 for a high carbon, 1065 or 5160 for a medium carbon, and some really low carbon mild steel are good for starters.

Stacy, we're talking "mystery steel" here right? Actually the alloy content (other than carbon) does effect how the steel sparks, which is where it gets tricky and "similar alloys" do spark similar, but not the same. However, they same steel will spark the same. You should be able to Google that information up.

It's a common misconception that the amount of branching is best indication of carbon content, although the branching or lack of it can play a role in identifying certain types of alloys. There are some high carbon alloys they use for dill bits etc., that have dull orange sparks with no branching at all, but the sparks still burn out close to the wheel like other high carbon alloys.

Low/medium carbon steels also throw sparks fairly far from the wheel, but tend to show more branching than the low.

The point is that with a series of in shop tests you can narrow things down and get a good general idea of what you have before you waste any time trying to work with them or having them analyzed. The first thing is to weed out the steels that aren't what you are looking for…

I think there is another misconception that working with mystery steel means picking up any old piece of steel and trying to make a knife from it. No! It means knowing what types of steels you ARE looking for, what they are commonly used for, and being able to identify them with some shop testing.

Since the alloy composition determines the properties of the steel, then by studying the properties of the steel, you should be able to determine the alloy composition,… or at least narrow it way down, through a process of simple deduction. However, a true chemical analysis should be considered a more accurate and detailed method when practical or warranted to apply.
 
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bladsmth said:
A test quench still wouldn't tell me what it was...just what it wasn't.
Stacy
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I really hesitated to reply to this thread, but... I think it would serve all knifemakers to be able to determine whether a piece of unknown steel is suitable for a knife blade. That means being able to tell "it wasn't" a hardenable steel. Beyond that curiosity may push you to further tests, but you'll know it won't make a knife without extraordinary efforts. If it had hardened then you'll know it may be worthwhile to do further testing, either in your shop or in a lab.
In all enterprises it pays to often return to the basics, before moving up to more technical means.

Alden
 
That's exactly right Alden! :)

If all the analysis really did was tell you that it "wasn't" (or isn't) suitable for a knife blade, (or wasn't/isn't what you were looking for)... that could have been determined in shop "first" by other means, without the analysis.
 
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Working with mystery steels, learning what works and what doesn't is a very valuable experience for the dedicated knife maker.

BTW, 01 and 10XX steels spark completely different :)
 
69_knives said:
I see 77% Iron and the remainder only adds up to about 15% or so. What is the other 8%?
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The numbers listed total 91.81%.

(So the missing 8.19% must be the block itself, which was destroyed by the testing, right? :p)


Mike
 
Tai Goo said:
Mike, I think 1095 or O1 for a high carbon, 1065 or 5160 for a medium carbon, and some really low carbon mild steel are good for starters.

Stacy, we're talking "mystery steel" here right? Actually the alloy content (other than carbon) does effect how the steel sparks, which is where it gets tricky and "similar alloys" do spark similar, but not the same. However, they same steel will spark the same. You should be able to Google that information up.

It's a common misconception that the amount of branching is best indication of carbon content, although the branching or lack of it can play a role in identifying certain types of alloys. There are some high carbon alloys they use for dill bits etc., that have dull orange sparks with no branching at all, but the sparks still burn out close to the wheel like other high carbon alloys.

Low/medium carbon steels also throw sparks fairly far from the wheel, but tend to show more branching than the low.

The point is that with a series of in shop tests you can narrow things down and get a good general idea of what you have before you waste any time trying to work with them or having them analyzed. The first thing is to weed out the steels that aren't what you are looking for…

I think there is another misconception that working with mystery steel means picking up any old piece of steel and trying to make a knife from it. No! It means knowing what types of steels you ARE looking for, what they are commonly used for, and being able to identify them with some shop testing.

Since the alloy composition determines the properties of the steel, then by studying the properties of the steel, you should be able to determine the alloy composition,… or at least narrow it way down, through a process of simple deduction. However, a true chemical analysis should be considered a more accurate and detailed method when practical or warranted to apply.
Click to expand...

I have been enlightened. Thanks, Tai.

Chromium also effects spark, makes for very energetic little bursts.
 
I'll tell you what that steel is good for,... It would make a good example of what type of steel you don't want for a knife blade and how that really low carbon stuff sparks. Can you send me a piece? I don't think I even have anything with that little carbon. :)

As a side note, I vaguely remember reading somewhere that high silica content is one thing that will inhibit the branching of sparks or starbursts in medium and high carbon steels.
 
The 8% could be many things. I know there are several elements that combine with metals, such as oxygen and chlorine that could be part of it. I asked Matt, and he didn't know either.
Stacy
 
Satcy i did (yesterday) find out what the missing element was in the test. Unfortunately the explanation is quite lengthy and frankly, not warranted here, since the steel is of no use to you or anyone else as intended. If you wish to discuss it feel free to give me a call.
Matt
 
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