Hardening 01 Steel ?

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deeps

Forager
Dec 19, 2007
165
0
Monmouthshire
I have knocked out a knife blank from 01 and put the bevels on it by hand. I now need to get it up to 800C to oil quench so next step is to make a simple furnace in the garden. However, would I be able to achieve 800C by using the gas rings on our kitchen range oven ?

Thought I would ask before trying cos it might help me avoid a domestic dispute, seems there is a household rule I was unaware of along the lines of no unnecessary blacksmithing in the kitchen !!!
 

Draven

Native
Jul 8, 2006
1,530
6
34
Scotland
I use a blowtorch on wee blades, but the problem is that the heat can be very localised, and it cools as you're heating the rest. Now I use my gas oven. I just crank it up to nine and hold the blade in the line of flames with pliers - gets a bit uncomfortable, but heats it up enough. .

Peace
 

robin wood

Bushcrafter (boy, I've got a lot to say!)
Oct 29, 2007
3,054
1
derbyshire
www.robin-wood.co.uk
I make a quick and simple furnace using a blowtorch and a pile of firebricks saved from old storage heaters you can see some pictures of it in use here http://greenwood-carving.blogspot.com/.
Make a little oven with the firebricks and aim your blowtorch into it, make sure its not airtight or the torch will blow out, best to have a small gap at the far end. Leave the torch running for about 10 minutes and the furnace should have heated up nicely, pop in your blade and keep a check on it for non magnetic. Its very controllable and you are not likely to overheat it with this system.
 
Jan 15, 2007
14
0
48
mansfield,notts,UK
I have made quite a few knives over the last few years, and what I use to harden the steel is a hole in the ground about 5 inches deep filled with charcoal. I then use a hair dryer attached to a metal pipe and it literally only takes about 5 minutes to get the steel up to the point it loses its magnetisim ( known as an arrest point, ar) and then oil quench it, the scale comes off very cleanly and the steel polishes up very quickly afterwards.
My advice is make sure the blade is reasonably well polished before you start the hardening process otherwise it is a nightmare to polish afterwards.
For tempering I use a shallow biscuit tin lid filled with enough water to cover the bevel and blowtorch over the knife spine ( known as differential tempering) until a straw with a hint of bluish colour appears over it, the water will ensure a hard edge and soft spine, or in an oven for 1 to 2 hours at 450F which will harden to between 56 to 59 rc.
Also water quench once desired temperature has been reached, as the speed of the cooling process is important.
For annealing 8 hours or so in wood ash, 15 minutes for hardening in oil quench and mere minutes/seconds water quench for tempering.
Also I recycle old files for knife making and they need to be hardened a little longer
than a purpose made piece of high carbon steel for knife making, as it is harder for it to keep a good edge for longer.

Hope this helps.

0390F Faint Straw 0199C
0445F Light Straw 0229C
0465F Dark Straw 0240C
0480F Brown 0248C
0500F Brown/Purple 0260C
0520F Purple 0271C
0540F Dark Purple 0282C
0575F Blue 0301C
 

Ogri the trog

Mod
Mod
Apr 29, 2005
7,182
71
60
Mid Wales UK
Hope this helps.

0390F Faint Straw 0199C
0445F Light Straw 0229C
0465F Dark Straw 0240C
0480F Brown 0248C
0500F Brown/Purple 0260C
0520F Purple 0271C
0540F Dark Purple 0282C
0575F Blue 0301C

Richard,
Thanks for posting the chart, do you have any aproximate Rockwell figures for the chart or is it too hit and miss?

Deeps,
I think a gas ring would be difficult to get enough of yor blade into for good heat distribution. I do most of my heat treating in a coal fired Rayburn in the kitchen, so the answers up to here are all perfectly do-able.

Let us know how you get on.

ATB

Ogri the trog
 
Jan 15, 2007
14
0
48
mansfield,notts,UK
I have just tried to copy and paste some tables in but they look messy, if you like pm me with your email adress and I can send them as an attachment for you. Also check out www.knives.com its a really good site to get the basics. Sorry Ogri forgot to say it is abit of a hit and miss affair if we are using pretty basic equipment, but the science more or else holds true in principle and I have managed to get some fantastic results.
 

big_swede

Native
Sep 22, 2006
1,452
8
41
W Yorkshire
Real men use induction, 30 kW with a 2.5 s prewarming time, cool with water and glucose for around 15 seconds, yields about 57-58 HRC..

RL, what do you use to measure HRC?
 
Jan 15, 2007
14
0
48
mansfield,notts,UK
My ethos for all my projects is in the spirit of doing it as cost effective as possible, and in a primitive way as much as possible, for example I use a hairdryer rather than using my traditional bellows sometimes in order to save breaking a sweat when increasing the furnace temperature, its down to instinct, intution coupled with knowledge and experience in order to achieve the desired result. As for using a 30 kilowatt heat blast which is electrically generated, that is not in the spirit of doing it in a bushcrafty way for me, but perhaps not everybody feels that way. Quenching in glucose is new on me I will have do some research on that, I have heard of brine mixtures, and soap, oil etc for quenching. But regardless of this all quenching at the final tempering stage usually takes the time of 2 to 12 seconds for any temperature between 80F and 180 F the main consideration is the duration of the vapour film in conjunctiom with the bath temperature when measuring these factors, but I will check out the glucose as for the HRC measurement terribly sorry all I know is that 450 F achieves a pretty close 56/58 Rc if you can maintain this temperature at a constant the only method of measurement I use is the time factor which can vary from what I have found between 20 mins to 1 hour approx, but unfortunately that is as far as my expertees goes in any academic way.
 

big_swede

Native
Sep 22, 2006
1,452
8
41
W Yorkshire
I was of course not serious about using induction. That would been a bit too expensive for the average household, I was more interested in how you came to the conclusion about the hardness. BTW now that I've had a bit of thought to it, I can't remember if it was glucose or some sort of glycole. I will get back on you on that.
 

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