HELP.....What did I do wrong??? Update: I got it right!!!

W

Wrenchbender_E

Joined
Jul 23, 2010
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25
I am currently deployed and decided to give knifemaking a shot using the primitive tools we have in the shop (vehicle repair shop).

I thought I did enough research prior to quenching it, but it doesnt appear to be much harder than it was before. I ran a file across it lightly and it is making a pretty good mark. To test the difference, I ran the same file over my commercial blade. No marks made.....

I'm using O-1 tool steel that my FIL sent over to me and I used old motor oil to quench it. I used the oxy/acetalyne torch and a rosebud to heat the blade up to "bright/glowing red" and dipped the blade into the used motor oil. It smoked quite a bit, but didnt bubble and catch fire like i had anticipated. Did I let the blade cool too much between the time I took the fire off of it and when I quenched it? Is it possible to quench it again or will that ruin it? Where do I go from here?

Any suggestions are appreciated.....thanks guys (and gals) :D
 
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have you tried grinding down a small amount?

when you heat treat a carbon steel blade, you can have a varrying amount of decarb on the surface, which you must then grind/file away. it is pretty thin, but it will have a lower carbon content and consequently be softer, even if the steel just beneath it is properly hardened.

it may be that the heat was not adequate, or that it cooled too much before quenching, or even that your steel was mixed up with another stock.
 
Color isn't always a good indicator of temperature given that it is greatly dependent on what the ambient lighting is like and such. A slightly more reliable indicator would be a magnet since when steel gets up around 1400F it goes nonmagnetic. Bear in mind that this isn't always hot enough to get a good heat treatment, but at least you know you have the steel hotter than 1400F.

Also, was the oil at room temperature or did you warm it up? Motor oil isn't the best of quenchants, but I understand you're probably limited in what you have access to.

You can re-heat treat it, but most would recommend you anneal it before quenching again. There will be a bigger decarburization zone as a result of bringing it up to higher temperatures more, so keep that in mind as well.
 
canid said:
have you tried grinding down a small amount?

when you heat treat a carbon steel blade, you can have a varrying amount of decarb on the surface, which you must then grind/file away. it is pretty thin, but it will have a lower carbon content and consequently be softer, even if the steel just beneath it is properly hardened.

it may be that the heat was not adequate, or that it cooled too much before quenching, or even that your steel was mixed up with another stock.
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I have not ground any of it down, but did take it to the wire wheel and try to get all of the decarb off of it. Does it take more than a wire wheel?
 
decarb and scale are sort of two different things. what the wire brush will remove is the scale. decarb is the area in the steel itself at the surface where the carbon content has been lowered.
 
01 is a very poor candidate for your limited equipment. It is not primitive friendly. Your torch and motor oil will get it hard, but it will not be a quality hard. All steel loses magnetism at 1414°, but you need about two shades of red heat above that, and even then 01 requires a soak at temp for around 20 minutes before quench. That would be from impossible to very difficult using a torch. You would find things much easier using 1075/1080 steel. It will respond very well to primitive and simple HT methods, and it is very cheap to buy. Being redundant, two shades of red above non-magnetic will do for most all simple steels, and some others. Warm your oil to around 125° to 135°, this acually cools the steel faster, and more evenly. Heat your blade in very dim light. This allows for you to see color change better. If you want to pursue the 01 blade you have, then just repeat with the above suggestions, although don't even try to soak it. I just don't think it would help enough to bother with, and if this is a knife to be used mostly in just cutting things, and not for stressful use, you will probably be satisfied, but do think the 1075/1080 steel for your next one.
 
OK, I was doing this more for fun than anything else. My FIL works at a steel mill and was able to grab me a piece at no cost, so I wasnt too worried about messing it up. I'm not going to be using this for much more than camping/hunting/cutting. I was unaware of the soak time required for O1, thanks for the info. I might try quenching once more to see if I can get a better result. I'll have to keep the heat there longer obviously to try and get those couple shades brighter, then move the oil closer so there is less time between fire and oil...
 
The steel has to go into the oil while it's still at color. Buy yourself a gallon of canola oil, and use that.
 
Yes. You do not want to lose any more time than to just turn and quench. Get everything positioned to this, including being able to lay down your torch, hand it to someone, or hold on while you quench. I would suggest ATF oil for the quench, but you need ventilation. That, and motor oil fumes are not good to breathe. Canola oil may be a tad fast, but would probably do. 01 does not require a really fast cooling. 10/12 seconds to go down to maybe 400°/450° will do.
 
I will second Canid has said. What everyone else has said is also true, but if I may tell a dirty little secret, the blade in my Benchmade edc is O-1 steel done by eyeball in my forge, and it works fine. It could hold an edge better and be a little tougher if treated in an oven, I have no doubt, but it performs easily as well as the original 154cm blade and unlike the original, has survived prying open cans of wood stain and paint without any tip breakage.
If you need any supplies or more steel, PM or email me. I can shoot a care package with some knifemaking goodies.
 
Brian Goode
uses O-1 primarily and HTs with a torch if he doesn't jump in soon contact him He is good (ha ha) people and I am sure would be willing to help you or advise you!
! Nothing wrong with trying !
We here stateside thank you for your service
 
Justin King said:
I will second Canid has said. What everyone else has said is also true, but if I may tell a dirty little secret, the blade in my Benchmade edc is O-1 steel done by eyeball in my forge, and it works fine. It could hold an edge better and be a little tougher if treated in an oven, I have no doubt, but it performs easily as well as the original 154cm blade and unlike the original, has survived prying open cans of wood stain and paint without any tip breakage.
If you need any supplies or more steel, PM or email me. I can shoot a care package with some knifemaking goodies.
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Thanks, I appreciate the offer, but I'm coming up on the end of my tour in a few months, so i prob wont have time to make another while I'm here.

UPDATE: So, I put it in the vice and started reshaping some of the belt sander marks, and low and behold, my file starts to skid after a few swipes :D
Guess there is some hard steel under the decarb! It's not great, or even, but I'm not overly concerned with that right now. I decided to test the hardness by putting an edge on it, and it's being a pain in the ass, so I guess thats good hardness. I wish you guys could see it right now. It's uglier than homemade sin, but its kinda cool that way. I will try and get pics eventually. Thanks again everyone for your inputs. I'll try to keep this updated and I'm sure I will have more questions in the future. You guys have been great! :D I'll be talking to you ........

WB
 
When heat treating without a controlled atmosphere you have to assume a bit of decarb. It is usually pretty thin if your heating time and # of cycles are minimal but thick decarb has fooled more than one maker, myself included.
Glad to hear your time was not wasted. Further filing will eventually just ruin your file. Welcome to the slow part of blade-making;)
Wish you a happy homecoming soon, my family and I are grateful for your your service.
V/R,
Justin
 
You can't leave it that hard. It needs to be tempered, now. Otherwise, it will be too brittle. The edge will chip, and the blade will break very easily.
 
Bill DeShivs said:
You can't leave it that hard. It needs to be tempered, now. Otherwise, it will be too brittle. The edge will chip, and the blade will break very easily.
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Bill is quite right, I suppose I assumed you had done this already, but if you havent yet you should put it in an oven and temper it twice for 2 hours each at 375-450 degrees or so, depending on how tough you want it to be.
 
a half assed option is to use a fire, torch or heat gun, but it takes a bit of coordination, timing and doesn't offer the most consistent results.

if you have to do it using one of these methods, remember that you are applying heat at temps much greater than you want the steel to get and that the surface and thin spots will tend to heat faster than the inner, thick parts, so you can hopefully see where the danger lies. such a treatment should be done, if at all, with the heat applied to the spine.
 
canid said:
a half assed option is to use a fire, torch or heat gun, but it takes a bit of coordination, timing and doesn't offer the most consistent results.

if you have to do it using one of these methods, remember that you are applying heat at temps much greater than you want the steel to get and that the surface and thin spots will tend to heat faster than the inner, thick parts, so you can hopefully see where the danger lies. such a treatment should be done, if at all, with the heat applied to the spine.
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I wish I had a propane torch....

So apply lightest heat i can manage from the torch to the spine and allow the heat to transfer itself down the blade until I get close to 400 degrees evenly? (I might have a digital thermostat somewhere around here.....) Then sink it in some "dry-sweep" and allow it to cool naturally? Do this twice?
 
basically, yes, remembering that it spends very little time at that temperature, so the transformation - if i have my theory straight - will occurr much less evenly as in a properly heat treated blade. this translates to suitably reduced hardness, but i think less substantially/reliably improved toughness.

i think historic methods have even included heating a heavier metal plate and applying it to the spine to accomplish the same thing.

remember that i'm not recommending these practices so much as introducing the option.

[edit to add: by whatever method, the temper has historically been determined by the color of the oxides that develop on the surface of the steel as the temperatures increase. this is also not as reliable as modern methods, and can vary from one steel to another.]
 
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I would clean the blade to shiny steel, then heat a larger/thicker piece of steel and draw the spine of the blade along it until the colors start to creep towards the edge, and quench in water or oil when the brown starts to reach the edge, or when the purple is 1/2" to 1/4" away from it. Do this as evenly as possible and leave the very tip until the end or you will over-heat it. I would repeat this 2 or 3 times.
You can heat the blade directly with your torch but the risk of over-tempering it is high and likelihood of getting any consitency is low.
 
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