Stupid steel question

G

Gendry

Joined
Jul 19, 2014
Messages
92
I know it's stupid, because I figure the answer is "no way to know/get it tested." I thought Id make a fool of myself and ask regardless.
What I have, is a, perhaps 36 inch diameter cement cutting blade. This thing goes on a machine you need a trailer to move, and they use it to cut up road at work. This one is missing a few teeth, so it's basically useless apparently. I am free to use it as I will.

I expect, at best what I have is a very large piece of thin steel to make "show" knives, or daggers with.

What can you tell me of this steel, which is used to cut cement? Is there a common type of steel for that application, or is it something I would have to have tested?
 
I've used those blades at work cutting concrete and asphalt, I have no idea what the composition of the steel is but the actual cutting is done by industrial diamonds at the edge. they cut forever but eventually do wear down. I had one warp on me to the point you couldn't run it.
 
With most saw blades now days, especially the larger circular blades, the cutting power / toughness is in the teeth. That's not to say that it isn't somewhat of a tough steel that the rest of the blade is made from, but chances are that it's no good for a knife.
Since all of the cutting is done at the very outside of the blade, so it really doesn't make much sense (anymore) to make the entire thing out of the same material. You actually want something a little softer so that the blade doesn't shatter or break when it gets over torqued or stressed.

Hence carbide tipped and/or diamond coated blades.

If you really want to know what the steel is, you might contact the manufacturer, but there's no guarantee they'll tell you.
 
first thing to do is to look at the teeth; see if they are brazed from different material.
Then cut a piece, do a spark test and try to quench it to see if it hardens. If not use it as a plate for making stuff, jigs and whatever :)
 
This subject comes up regularly, and the vast consensus is that they are not good for knife blades.

I had a concrete cutting company give me a half dozen of those 24" to 36" blades. I had one tested. It was a chromium bearing low carbon steel similar to 4140. The steel is designed to be tough, not hard.


What they are good for is tomahawks and Viking broad axes. The .35-.45% carbon will harden in an oil quench to some degree. Temper at 500F and it gets a hardness in the low to mid Rc50's. Cut out a big butterfly fold/wrap the wings around and forge weld together. You can slip in a piece of 1095 in the fold for a high carbon bit if you want a serious cutter.
Because they are lower carbon steel, you can cut the blanks out with a cutting torch or a plasma cutter. Allow a little grinding room to trim away the slag and HAZ.
 
I work masonry and have access to as many 14 to 20" diamond blades I could ever want. Like Stacy said they can be used for projects that don't require knife edge hardness. I have made a few throwing knives out of them and they do fairly well at that.

Chris
 
A lot of my peers use concrete blades to make throwing knives. Steel is 8670 or 1080 at best. Hardness is usually in the low 40s. It is reasonable to think that they are at the maximum hardness allowed by the steel.
 
Concrete blades, to my knowledge, are bad steel for knife making. Buzz saw blades, the old ones with the teeth that are part of the blade(not braised on) will make a great knife. It falls in the 1070-1084 range 90% of the time.
 
You must log in or register to reply here.
Back
Top