Heat treating axe heads

[cutt]

When you heat treat a axe. then quench it. The axe should be non magnectic correct? A file should skate across the edge, and a magnet should not stick to it. When you temper the head does that make it where a magnet adhire to it? All my axe heads that I have not restored my magnet sticks to the edge. If or when in the process does the finished edge get where a magnet sticks to it? Thanks fella's.

 

[Fabsmith]

lol no sir. you heat till non magnetic before quenching. its always magnetic as its steel and most likely not stainless. but as soon as the material cools its magnetic properties come back. for steel to be non magnetic it has to be extremely hot. almost melted hot. there are exact numbers and info on this but this is just the general idea to put you on the right road

 

[cutt]

Thanks Fab. That is what I was wondering about. When it goes back to magnetic ?

 

[cutt]

Welcome to the forum Fabsmith

 

[jumbojak]

Thanks Fab. That is what I was wondering about. When it goes back to magnetic ?

Steel loses its attraction to magnets when its crystal structure transforms to austenite at high temperatures. When it cools, depending on how you cool it, different structures will form and it will again be attracted to magnets.

 

[cutt]

Thank you jumbojak

 

[RPH]

The non magnetic part is the curie effect. It usually occurs around 1700-1800 f*. Depends on the alloy. Getting it hot is the easy part. Quenching is a science itself with the polymers now available. One of the biggest problems with backyard quenching is the steam layer that forms at the hot steel. Systems are designed to blow that away and the polymers work on it too. If it isn’t cooled even and quickly you stand the chance of not freezing the micro structure where desired. Hardening will produce an extremely hard surface but it will be brittle. This is the anealling process enters. After hardening the part is exposed to a lower tempeture, 600-1000 f* for a period of time. This allows the hardened microstructure with some give to remove the extreme brittleness. It can still break.

 

[cutt]

Thanks RPH

 

[Bretny]

It really needs a high carbon content to make the work worth it.
This isnt a new axe head is it?

 

[matt_i]

Its important to have some idea of how fast to quench the part to "freeze" the microstructure. That depends on the base material.

For example in tool steels one can have O-1 oil hardening, W-1 water hardening, and A-2 air hardening. High carbon 1070-1090 is a different animal too.

I usually temper tool steels in the kitchen oven, polish part of it back to bright/silvery and then go roughly 500F to a golden "light straw" color. Probably 1 hour soak per 1" of thickness of the cross section. Then remove and just air cool.

 

[cutt]

These are old axe heads that I want to restore and re-handle. Thanks everyone for all your great input.

 

[bdbecker]

Another thing to think about with this project (if you haven't already), you'll only want to treat the bit of the of the axe so it holds an edge, the rest you'll want to keep "soft" so it it maintains ductility and doesn't crack under use. There are some very good how-to's on some knife/blade specific forums.

 

[Lelandwelds]

Council Tool has some decent photos of the axe heat treat and grind process. Usually just 3/4" to 1.5" from the edge is heated. The edge may be quenched faster from partial immersion or from greater mass near the eye. Google "differential heat treat" or "hamon line".

5160 makes great axes. (Old leaf springs from heavy trucks.)

 

[Rbreddin]

OP, you've been watching forged in fire too? lol

 

[cutt]

Yeah, I'ved seen FIF. OK but I was already into doing axe heads.