Annealing

[Herr_Mingus]

hi chaps

I recently got jim horisiuis (?) book on bladesmithing (forget exact title). It refers to annealing in several places , im familiar with the process of annealing but he is a bit vague as to at what point in forging it should be done.

should steal be annealed before you attempt to cut it? should it be annealed before you attempt to work it in the forge?

cheers

Nathan

[Sajuma]

If you are for example working with ball bearings, they have to be annealed before you do anything with them, othervise they might even explode. To anneald steel is to draw the hardness and tensions away from it. Annealing is always recommened if you are not 100% sure that it's done already in factory. It is good to anneal steel after forging before HT, this way you dont have extra tensions in your blade.

Juha

[Kevin]

Nathan.

Annealing is used to get the steel as soft as it will get and relaxes any stresses built up .

If your using stock removal, than annealed steel is easier to work.

I dont know anything about forging bearings...but generaly when forging, the annealing stage is after forging to shape and before any grinding before heat treatment.

When forging a lot of stresses can be put in the steel and if its worked too hot then the grain size will grow.....That is not a problem. The way around it is to reduce the working heat during the final stages of forging (a red heat rather than an orange)...Then, when you have finished all your forging 'triple normalise'......That IMO has to be one of the most important steps in forging. To 'normalise', slowly bring the blade to non magnetic...its very important not to go over this heat. Let it air cool to a black colour, then repeat 2 more times (3 normalisations in total).....If done right, the grain structure should have shrunk and it will make a good blade.

When its time to heat the blade for the final heat treatment, its also very important not to exceed the critical temperature or else it will undoe the process u have just achieved!

Annealing is pretty similiar to normalising, but instead of air cooling, you need to slow the cooling process down as much as you can to be effective. I either bury the blade steel in wood ash and leave it overnight or I turn of the gas in the forge and leave it cool down with the blade inside.......cooling like this can take several hours.

[Herr_Mingus]

thanks coutel , some really helpfull info there.

[keith_beef]

Annealing is used to get the steel as soft as it will get and relaxes any stresses built up .

..snip..

Annealing is pretty similiar to normalising, but instead of air cooling, you need to slow the cooling process down as much as you can to be effective. I either bury the blade steel in wood ash and leave it overnight or I turn of the gas in the forge and leave it cool down with the blade inside.......cooling like this can take several hours.

Here's what my G.P.Wall book says about annealing.


Annealing

The object of annealing is to releive the internal stresses caused in the forging, rolling and rapid or irregular cooling.

By elimination of these strains, steel is in the best possible condition for either hardening or machining.

To anneal steel efficiently, and to completely refine the grain, it requires heating to slightly, but only slightly, above its decalescence point (commonly called the upper critical point -- not exceeding 20° C. higher for Tool Steels and medium Carbon Steels, and 30° C. for steels of low Carbon content-- and allowing to cool slowly in the furnace, sand dry ashes or lime. No advantage s regards softness, is gained by heating to higher temperatures; in fact, any overheating in the anealing process impairs steel, causing a coarsening of the grain and generally weakening the material. This harmful effect of overheating becomes exaggerated as the excess temperature increases. This is especially the case with "Tool Steels".