You might do well to seek advice from the British Blades Forum as well

Good luck

Hi Brian, have look at these two links but definitely quench in oil NOT WATER, best if you can get some substitute for whale oil rather than "any old oil" If not probably a thin oil will be good enough but not motor oil it's generally too heavy.

I have seen these and 8" long seems rather large, most I have seen are 4/5" long X around 4" wide, in any case you will need a large container of oil I would suggest a minimum of 5 gallons better if it was more and depends on how many you are heat treating at a time ? Also remember they must go "edge first" into the oil not flat to minimise warping.

Tempering I would suggest 300 deg C soak for 30/40 mins at this temp and quench in oil. These need to be very tough with reasonable hardness.

John

**LINK**

**LINK**

Edited By JohnF on 30/05/2016 23:05:50

To do the best heat treat you really need to be sure of the metal.

Ground flat stock is most commonly 01 and is a good blade material. You can't do better than follow the suppliers instructions for temperatures. You can, however, refine the grain, which is not often in the instructions and can significantly improve toughness.

If you can't find instructions, try this:

Heat to 870C and and cool in still air

Heat to 830C and cool in blown air.

Heat to 800C and cool in blown air.

Heat to 800C and quench in oil – any oil, veg oil, engine oil.

If you have tight temperature control at those high heats then you can soak for a while quite safely. I don't think you need to for a blade, but 5 or 10 mins should do it. The first heat is more important to soak than the last.

If you don't have good temp control, then don't soak at high temp for long – just get it to temp.

Temper at 220C for one hour – a bit longer if a really thick blade. Some O1 guides suggest a toughness peak at this temp – going a little higher can reduce toughness.

Heat treat may result in breakage.

8" long, 1/2" thick is outside my experience and longer soak times at high temp, and higher temper may be more appropriate – find the instructions!

If the 'tool steel' is not O1 then it may be air hardening and oil quench could be too risky. If in doubt, and you want to be safe, first 'quench' in air and see if a file skates on the surface… if not then quench in oil. Repeating heat treat is OK, quenching too slowly does no harm – it just doesn't get hard. Quenching too fast will result in breakage.

Edited By jaCK Hobson on 31/05/2016 08:35:44

Edited By jaCK Hobson on 31/05/2016 08:39:13

Edited By jaCK Hobson on 31/05/2016 08:43:36

If you have a number of these to do (it being industrial sized) you will be surprised at the cost of commercial heat treating – I use Wallwork and they charge by weight. They will give you them back in exactly the condition you ask for and will often be able to advise what treatment is best for the material and use.

Mark

When you say "tool steel", you need to be a bit more specific. The supplier should be able to give you a more technical specification as well as the recommended procedure for hardening and tempering whatever he has sold you. There are many dozens of tool steels with widely differing requirements, some very challenging to implement in a home workshop. Ideally you'd consider this before purchasing said steel….

You might think that 8" x 2"/3" x 1/2" is big, a local lad has built one a little bigger, its built on a large truck, the hydraulics are driven by a 300hp V8 diesel engine, first you put the log in length wise(about 3 meters long x up to 1 meter dia), that splits the log in about a dozen bits, this lot gets turned side ways, and chopped into firewood lengths, whole job about 2 miniutes. I think the steel used is something like 4140 with Stellite hard facing weld on it. Ian S C

Gauge plate or Flat Ground Stock etc. is definitely what they call 'tool steel', I think from memory its basically an 01 steel packaged in convenient ground sizes.

Tony

I agree with MarkC and Dusty that you should use a professional heat treat service. They use a controlled atmosphere furnace that prevents scaling and decarburization. As long as they know what steel they are dealing with they can deliver your parts to the exact hardness you specify.

This guide shows it as pretty straightforward to harden and temper, except the requirement for tempering for is two hours minimum!

Neil

http://www.westyorkssteel.com/files/en8.pdf