After Heat treating Blotches On Steel HELPPP

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nickBiddle

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May 15, 2013
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i dont know what im doing wrong but its pretty much all over my first knife i made i just sanded it down till i couldn't see it no more but i On my second knife know i would like to know what it is. i heard it was ether the air flow in the forge or its not getting hardened fully or something








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what are you using for quench oil and at what temp are you heating up to. Are the spots deep ? Sometimes when I first started I would get a deep blotchy looking blade. I was overheating the blade and I was using the wrong oil. I was using motor oil because I was to cheap to buy quench oil and all my blades would snap in half after tempering with very large grain. So all my work was done for nothing.

How about you. You have to give a some more details.
 
Also what steel are you using? could be from your tongs like chuck said maybe causing vapor jacket?? or as marko pointed out the wrong speed quench. could even be an imperfection in the steel. Im sure someone will chime in with the correct answer here soon. But its good your not taking the "who cares" route.
 
im using motor oil and 01 tool steel im waitn to get the magnetization out then i quench then i put in oven at 425 for a hour
 
Hi Nick..01 needs to be pre-heated at around 1250 F and brought up to 1475 F and soaked 10-20 min should also consider doing a double temper. I do 2 hours twice. I just hate to see you waste your time with that method on O1 , This is just how I do it . Others may be a little different.

If you only have a forge to do your heat treating you should pick up some 1084 you can make a nice blade in a forge with that steel.
 
That appears to be simple discoloration from the quench process. That happens when hot steel meets oil. It should easily sand off. Just so you know, non-magnetic is not an indicator of when to quench. You need another 50°/60°, or roughly a good shade of red above that point. Aside from that, you will not get the full potential out of 01 without a source of controlled heat so that it can be soaked at temp for a while. With your limited equiptment you would be better off using 1080/84 steel which would give you much better results, and it is much cheaper to buy.
 
At minimum for O1, get a pyrometer with a thermocouple in a ceramic sheath (less than $100.00 from Auberins) to get control over the temperature. I have two broken O1 blades from lack of heat control. With the soak times needed for O1, a flux or mechanical shield will help prevent excessive decarb in a gas forge. Use canola oil instead of motor oil, and heat it to 120f or so on a hot plate. O1 is not difficult, you just need more control than some of the simpler steels like 1084. I use 2 temper cycles, 1h each with fully cooling to room temp between.
 
Marko3 said:
Hi Nick..01 needs to be pre-heated at around 1250 F and brought up to 1475 F and soaked 10-20 min should also consider doing a double temper. I do 2 hours twice. I just hate to see you waste your time with that method on O1 , This is just how I do it . Others may be a little different.

If you only have a forge to do your heat treating you should pick up some 1084 you can make a nice blade in a forge with that steel.
Click to expand...

+1, good method for HT. The discoloration you are seeing is normal and shouldn't be very deep. It is a combination of the raw nature of heat application in a gas forge (raw open flame) and then the motor oil being pressed past its heat parameters. Remember motor oil is only designed to handle temps in the 500-600 degree range and not triple that from hot steel.
To minimize it, follow the above process, get a quality quenchant, and make sure you are running the forge just a little lean.
You will still have a little bit of scale, but I isually account for it and can knock it off with 320 grit which is where I start with finishing after HT anyway.
Never use used motor oil BTW... bad Juju. Water trapped in the used oil can flash boil causing mucho problemos... Even some blends of new motor oil, atf, and brake fluid can have suspended polymers and other nasty things that one doesn't want to breathe in vaporized form...
 
thanks everyone for helping i will try a diffrent quench instead of used motor oil i just followed the Instructables how to build a knife. i tested my knife thouroughly and nothing happend but i will try again after i finish this knife
i have a propane torch form harbor freight http://www.harborfreight.com/propane-torch-with-push-button-igniter-91037.html then i have fire bricks when i get some time i will show you guys maybe you can give me some better advice i really tourch the hell out of it becfuase the first time i got my knife out of forge the file scracth the heck outve it buit my second attempt the file just glided over so i though i was good

here i s a pic of my first knife lol i sanded away my bevel i didn't know what i was doing lmao

awdvc.jpg
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I've seen worse firsts. Just keep at it. I'm pretty new to this as well, and have broken several blades from improper heat treating. You learn through experience. I had aspired to heat treat my own blades regardless of what kind of steel I used. I now know that sometimes its better left to the pros, and I will be sending them out to get treated.
 
nickBiddle said:
thanks everyone for helping i will try a diffrent quench instead of used motor oil i just followed the Instructables how to build a knife. i tested my knife thouroughly and nothing happend but i will try again after i finish this knife
i have a propane torch form harbor freight http://www.harborfreight.com/propane-torch-with-push-button-igniter-91037.html then i have fire bricks when i get some time i will show you guys maybe you can give me some better advice i really tourch the hell out of it becfuase the first time i got my knife out of forge the file scracth the heck outve it buit my second attempt the file just glided over so i though i was good

here i s a pic of my first knife lol i sanded away my bevel i didn't know what i was doing lmao

awdvc.jpg
[/IMG]
Click to expand...

Change your heat source, or change your steel. It's really that simple with the equiptment you have. And yes, change your quench oil to canola, or buy real quench oil. If you will get some 1080/84 steel, you can do very well with what you have. Plus a little more instruction on the HT in general.
 
Oh, I thought you had a forge... Fire bricks + a torch do not make a forge. Heat is still way too localized... It doesn't take much, less than $10 worth of stuff, to make a decent burner. Add a high pressure propane regulator ($20) from your local propane supplier and you are in the mix. Pm me and I can send you a description and parts list that will get you forge welding heat at 10psi... Mine is a real gas sipper and hyper adjustable. With a thermocouple monitoring the temp I can not only forge and HT, but also temper by just adjusting a couple of things...
If you wish to stick with a torch, try the previously listed 1084, 1075, etc. Also, run your bevels further up the blade. Fat and chunky chopper style is hard to get good heat penetration plus the other drawbacks. Nice and thin you will get a hard cutting edge even if you fall short on the rest of the blade.
Cheers.
 
Oh, realize that sounded weird. A lot can be done with a simple one brick or coffee can forge and a good torch, but it's not nearly ideal.
And take instructables with a large grain of salt. Seen a lot on there that makes me cringe....
 
A weed burner and a few firebricks will barely get O-1 steel hot enough for hardening ( as you found out). It won't keep it at the right temp long enough to harden it properly at all.

Using 1084 steel, the torch you have, a dozen or so soft firebricks ( you don't want the hard ones), a magnet, and 120F canola oil, you should be able to get a reasonably good HT.

Stack the bricks in a long tunnel with the torch coming in from the back corner at an angle. About a 3"X3"X12" tunnel interior is what you want. The flame should sort of swirl around the tunnel walls from back to front. You have to play with how the torch sits at the entry point. Sometimes it is close to the hole, and sometimes it is just barely in the hole at the bricks.
You can just stack the bricks, or make a more permanent arrangement by jointing the bricks with fireplace cement ( hardware store) and pinning them together with long nails or pieces of stiff wire. A few twists of bailing wire will help keep it all together for a while.

Run the torch for a few minutes to heat up the bricks and then put in your blade. Using tongs or long handled pliers from Harbor Freight ( see below), move the blade in and out and turn it constantly. Stick the magnet ( see below) to something near the "forge" so it will be handy when needed. As the blade gets red, pull it out and touch it to the magnet. It should stick at plain red, and then as the blade gets a bit hotter and redder, it will suddenly stop sticking to the magnet. This is about 1350F. You want to make the blade around 100F hotter than that, so heat about one shade of red more, make sure the whole blade is evenly red....but the edge is what you want to pay attention to....Don't let the edge get super bright cherry red! ( that's too hot). Once the blade ( or at least the edge area) is the right temperature, immediately quench in at least one gallon of 120F canola oil. Plunge straight in like you were stabbing the oil. Move up and down, but not from side to side. Keep the blade in the oil for at least one minute. Take out and check with a file to see that the edge is hard. If it is, gently wash the blade with soap and water and then place in the kitchen oven at 400F to temper for two hours. Pull out and cool off in running water. Put back in the oven for a second two hour temper. Do these tempers as soon after the quench as possible.

BTW - You heat the oil before you start by using a piece of metal rod ( rebar or whatever) in the forge and plunging it in and stirring the oil. Once the oil is about 125F, you can go on to heating the blade. A cheap HF digital thermometer ( see below) will work for checking the oil temp ( Before you ask, the HF laser thermometers are useless for checking the hot blade temp).

This will give you a good hardened and tempered blade that will cut and last well.

Here are some good beginners things from HF:
http://www.harborfreight.com/16-inch-long-reach-pliers-set-38598.html
http://www.harborfreight.com/15-inch-long-reach-locking-pliers-97609.html
Magnet:
http://www.harborfreight.com/4-3-4-quarter-inch-multipurpose-magnet-holder-1938.html
Thermometer:
http://www.harborfreight.com/hand-tools/thermometers/instant-read-digital-thermometer-95382.html
 
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I have a Tiger Torch, which would get to 1850 or so according to my pyrometer with 10 carefully stacked firebricks. To keep it below 1600f, I needed to slow it down to almost stalling out. I suspect different brands have different outputs. I tried 2 handheld torches previously, and with two full open, I only got to 1250f. For that forge, I have this pyrometer, with the ceramic sheath for the thermocouple: http://www.auberins.com/index.php?main_page=product_info&cPath=17&products_id=199 I can get the basic forge within 10f of where I want it, and hold those temps consistently.
 
ok so that pyrometer do i leave it in forge or touch the steel with it im confused should i not be having a direct flame from torch on steel ??
 
The pyrometer thermocouple is in the forge, in the sheath. The blade and thermocouple are inside a 1/2 pipe to shield them from the direct flame. The 1/2 pipe radiates the heat which is read by the thermocouple/pyrometer.
 
A pyrometer and a muffle pipe will require a real forge. A brick tunnel and weedburner won't cooperate enough to get a good temp regulation.
 
The pyrometer reported the temp in 1f gradients. I could hold the temp within a 10f range inside the muffler for 1/2 hour, without adjusting the flow, and with slight adjustments longer, once settled at the temp I was aiming for. It took a bit of up and down to hone in on the range, but once there it was steady. I can guarantee it is not the easiest way to get temp control, but with a little bit of playing with the angles, and carefully placing the 10 firebricks with no gaps- basically the same as a rectangular atmospheric forge. I wasn't sure I could do it, but when parts for my blown forge were late coming in, I used this for 6 blades. I broke 2 by overheating as the forge came up to temp, learning to use the muffler, and to not trust the reaction time of the pyrometer with larger/faster temp changes. If it was changing less than 1f per minute, I trusted the temp it was at. I am not using a weed burner either. I have an industrial tiger torch (in the old setup.) The blades had a uniform red color coming out of the forge, significantly different from my earlier attemps with heating with the torch in a nonshielded or enclosed flame.
 
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