Tempering and hardness

E

Evan.S.Merritt15

Joined
May 11, 2018
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I have an old industrial saw blade meant for cutting aluminum that's from an extrusion plant. I plan on cutting out a design for a knife from it and all I have to do after in the way of heat treating is temper it because it's already hardened. Problem is I don't know what type of steel it is so I don't know how long I would need to temper it for or what temp I would need to temper it. I looking for around a 56-58 hrc. How long and what temp should I temper it for?
 
Evan.S.Merritt15 said:
I have an old industrial saw blade meant for cutting aluminum that's from an extrusion plant. I plan on cutting out a design for a knife from it and all I have to do after in the way of heat treating is temper it because it's already hardened. Problem is I don't know what type of steel it is so I don't know how long I would need to temper it for or what temp I would need to temper it. I looking for around a 56-58 hrc. How long and what temp should I temper it for?
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Impossible question to answer.

Hoss
 
If this metal is already hardened, how you plan to cut it out without ruining the existing HT? You say you want 56-58 Rc, any idea what it is now? As Hoss says, "impossible to answer".
 
Evan.S.Merritt15 said:
I have an old industrial saw blade meant for cutting aluminum that's from an extrusion plant. I plan on cutting out a design for a knife from it and all I have to do after in the way of heat treating is temper it because it's already hardened. Problem is I don't know what type of steel it is so I don't know how long I would need to temper it for or what temp I would need to temper it. I looking for around a 56-58 hrc. How long and what temp should I temper it for?
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You would cut into coupons and temper with different temps and use a rockwell tester to build a range of hardnesses.

Sounds like a lot of work for something that is being done to be low cost and it's not going to have any crazy performance.

It's honestly just cheaper to buy legit steel for knives, especially if your looking for something specific.

$5-10 for a piece of steel, no big deal.

It's the work that's expensive.
 
I don’t know of any 15 year olds that own a Rockwell tester.

It’d be best for you to find a knife maker in your area to help you, one with a rockwell tester.

Hoss
 
Yes, no equipment, no experience, no idea what he has or how he is going to make a knife from it.
 
He's only 15
Great age to be taking an interest in this
Start by reading the stickys here and get yourself some basic tools and start to make
If you love it like we do keep at it
 
Good advice up there. Without a tester you won't know the exact hardness. There are files you can get which can give you and an idea within 5 hrc but you're obviously trying to do this cheap. Hardness test or are expensive. You may have a local machine shop that could help you test it. As you're likely starting out (I'm assuming this is you first knife) dead box made a good suggestion. It'll be a good learning experience. Cut out 5 pieces say cm wide by 5 cm long. Temper them at say 0 300 350 400 and 450. Them clamp then in a vice and break them. Be careful and use glasses. This will give you an idea about the steel. If it bends and sets before breaking it's too soft for a usable edge.

Some saw blades are only hardened at the edge so be aware of that. The concern others have is that if it is a hard blade you won't be able to use a hacksaw or band saw to cut it out. You will need an angle grinder, plasma cutter, water jet or laser. You probaby intend to use an angle grinder and these generate heat which will destroy any temper.

Also if it is hard you'll need a belt grinder or angle grinder for shaping the bevels and have the heat concern again. Files won't work. You'll also have a hard time drilling pin holes.

Unless your able to reharden the blade (you always could try an edge quench with a propane torch) you won't get a usable knife and it will be a lot of diffecult work. If you're able to get proper steel you'd be much better off. Heck, even a piece of mild steel from HD is a good place to start. You won't be able to harden it but at least you can learn on it.

Good luck.
 
Evan,
I hope you didn't take my comments the wrong way. We see a lot of young folks come here with ideas on how to re-invent knifemaking. Most want to start with some unknown steel object. The stickys has a lot of good information.

As a general rule, saw blades don't make good knives. Most are made out of metal types that are tough, not hard. This is great for a saw blade, but not so good for a knife. Many have the outer edge hardened by some industrial technique, or the teeth are carbide that is welded on the blade disc.

Filling out your profile info would tell us where you live. That could allow a nearby maker to offer you some good steel or help testing your saw blade. Lots of us here send a bar of steel to a new maker. Sometimes I profile it to their desired shape because they don't have the equipment to cut it.
 
Well I have most the equipment to do it. I have welding class and machine tool class and in machine tool class we're getting a new heat treater machine. I think machine class may have a hardness tester? I'll check but if not I'll find a way to work.
 
Evan.S.Merritt15 said:
I have an old industrial saw blade meant for cutting aluminum that's from an extrusion plant. I plan on cutting out a design for a knife from it and all I have to do after in the way of heat treating is temper it because it's already hardened. Problem is I don't know what type of steel it is so I don't know how long I would need to temper it for or what temp I would need to temper it. I looking for around a 56-58 hrc. How long and what temp should I temper it for?
Click to expand...
Can you take picture of that industrial saw ? That would help . . ..
 
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