quenching material

[redmegalord]

okay so in my research ive come across several different materials for quenching in. ive found that people will quench in oil (what type, and does the temperature affect it at all?) water (again, does the temp matter?) animal tallow (not really sure what this is, dont really get the concept but from my understanding its animal fat which to me means that its more hazardous than most other materials) brine (yall know what brine is, im actually really interested in this one, i wonder if the salt has any kind of adverse effect on the steel but once again does the temp matter?) and air (i have no means of doing it this way but im still interested to know how its done) is there any discernible (or not so disernible) effect on the steel depending on which of these materials you use for quenching? any advice would be greatly appreciated.

[Bambii]

I used some old motor oil i found in my garage. Water cools faster than oil and it has a greater risk of cracking the metal you are quenching.

I have heard of quenching water in brine, i dont know about that really.

Tallow? I wouldnt quench in that, probably stick to the metal like hot wax?

[WoodTroll]

I use motor oil myself. Seems to do the trick. I've used vegetable oil too.

[greenpete]

I use motor oil myself.
http://www.greenpete.co.uk/knife-making/

[CanadianMike]

Really depends on the steel you are using. Some like O1 don't like water quenching (incidentally, it's called O1 because it's Oil quenching, 1% carbon), etc. All I've used is dirty motor oil, mainly because I love the black scale I get on the steel. I water quenched a blade early on, didn't do it right and was a thin edge, heard the "Ping of Death" and saw a half inch crack in the edge. Mind you it was room temp water. And watch out for brine, I read it cools steel faster than water, so you are at greater risk of PING! than with water.

[redmegalord]

alright guys thanks, a lot of great advice. so now i have a couple more questions, the first being what temp should the motor oil be? the second is what dimensions should the object im using to contain the oil have? and the third is does it matter if the oil is dirty or not or am i overanalyzing things?

[greenpete]

or am i overanalyzing things?
Yes.. a lot!
I recommend you watch my video, then come back if you have anymore questions, which if I have done my job right... you wont!
Oil at room/woodland temp, dirty clean, what ever you want.
Size of container should be big enough to take the blade you're making!

[redmegalord]

gotcha. and by the way ive seen your videos quite a few times, ive even watched them with my fiance. its just that since i live in the city (not by choice, small town guy i dont do well being so close to so many people, believe it or not you lose a lot of freedom living in the city, and its incredibly claustrophobic) its not so easy to accomplish even the most basic parts of making a knife. for example id rather have an open fire rather than using a weber grill and charcoal to anneal the file, and instead of using another file for all the shaping work id rather use a grinder but because of noise restrictions i cant use power tools like that. what im saying essentially is that im in the worst possible situation for making a knife (broke, no car, in the city etc etc,..) i need some good steel at my hip, and truthfully i really need a hobby lol and its especially important now because my leatherman c33l just failed its outdoor tests, i got it in my head to try batoning with it, it failed with flying colors.. and my only other knife is a sentimental piece, so im pretty much out of options at this point.

i really dont mean to go on and on, i hope you dont think im complaining but you need to know a little of my situation in order to fully understand the difficulties involved. thanks again for all the input, it will definitely come in handy when the time comes.

[WoodTroll]

Here is a good tutorial on Heat Treatment and the like.

http://www.navaching.com/forge/heattreat.html
:):):)

[CanadianMike]

Honestly, I watched GreenPete's series early on and learned from it.

Here's what you do if you are in my situation as far as location goes:

1/ If you can run a charcoal BBQ in your backyard, get a charcoal chimney:

http://t2.gstatic.com/images?q=tbn:ANd9GcQczpF8cLt80Wh3gJZgeteqDGwu50sIu JRcVwec_yPffCRtMe8oeXMenW9CPQ

Is all I've been using the past four months to heat treat steel, works great! Now that it's winter, I'm working on a small two brick propane forge.

For profiling, get a cheap 1" x 30" belt sander, and a selection of various grit belts. Is really quiet compared to a grinder, and takes steel off WAY faster in a more controlled way. I have one something like this, and have made about a dozen knives so far using one, with grits from 50 to 1200:

http://www.harborfreight.com/media/catalog/product/cache/1/image/370x/9df78eab33525d08d6e5fb8d27136e95/i/m/image_76.jpg

Past that, is really mostly hand work with sandpaper, etc.

Oh, I made a jig using a table saw to give perfect angled bevels:

http://sphotos.ak.fbcdn.net/hphotos-ak-snc4/hs958.snc4/75143_454458444206_510619206_5173336_4747730_n.jpg

Which gives me results like this:
http://sphotos.ak.fbcdn.net/hphotos-ak-snc4/hs968.snc4/76121_469709314206_510619206_5393836_8124721_n.jpg

[dave budd]

Some of this is repeated from what has been said above, but I'm, ini mid flow so will carry on regardless!

Heat treating can be as simple or as complex as you want it to be. The more complex you make it, the more chance of it being as good as you can get it there is, assuming you know what you are doing and more importantly why you are doing each bit ;)

simple:

1) get it hot
2) get is cold
3) get it warm

1) Heating. bring it up to red hot until a magnet no longer sticks to it. The best actual temp for hardening is going to be a bit above or below depending on the steel, but this will work fine for most simple steels. So bring up to temp, when it doesn't stick put the blade back into heat and count to ten. Then quench.

2) Hardening. as soon as the right temp is reached go STRAIGHT into the quenchent, don't hang about or it will cool too far before you quench it. You want to cool the steel down as fast as possible to get it as hard as possible, but the faster it cools then the more stress is involved (more stress = warpage and cracking!). The quenchet you use will depend on the steel, the intended result and the thing you are hardening. Generally though, most mid to high carbon steels will be best in oil. Try heating a scrap piece of the same steel to non-mag and quenching in oil. if a file still bites it then try again with water. If the file still bites then try again with brine. If it still bites then try mixing some soap into the brine! If you know the steel to be good and you can't get it hard then most likely you aren't getting it hot enough (or way too hot).

Some oils are faster than others. Motor oil is ok, but not good for you and also creates a lot of flamage! veggie oil is fine, peanut oil being the best on account of a high flash point and being quite thin (so is faster than a thicker oil). Tallow is fine, I use it all the time at shows and for some of my courses; its a bit sticky but a rag and a bit of soap (or wood ash) cleans and degrease it fast enough. Tallow is a fast oil when molten, so some steels will cool too quickly.

The larger the container of oil the better, but as long as you have a few inches around every aspect of the blade dropped into it, then you'll be fine. Pre heat the oil to make it more efficient (about as warm as washing up water). If its cold then the oil is too thick and doesn't transmit the heat away from teh blade as fast as it could; if its too hot then it won't cool it fast enough either. If I've hardening a lot of big things like axes then I have to coo the 30L bucket down every other head to keep it working at its best.

3) Tempering. This reduces the hardness and brittleness, the higher you reheat to then the softer (and tougher) the steel will be. The old way is to clean back to bright metal (bit of broken waterstone, sandpaper, etc) and then heat with the coals from teh fire/hot tongs/blowtorch until you see colours forming on the surface. Each colour (an oxide) forms at a different temperature, so if you know that O1will be at RC62 at 200C, then when the correct colour for 200C appears you can cool the blade off (water is fine) and you should have a blade at that hardness. The trouble it that each colour will dictate a different hardness depending on the steel (try putting three different bits of polished steel in the oven at the same temp and see the colour differences!), also tempering by colour is a bit of a skill to do well. Most medium carbon steels will want somewhere between golden straw and dark brown for a working hardness (but some like 52100 will be more like purple at 60RC). Alternatively, bung the blade in your kitchen oven for an hour at the correct temperature according to the steel manufacturers

The more complex ways to do the above mostly involve greater control of the atmosphere, temperatures, time at temp and speed of cooling.