?'s about treating 1095 and 1084

[Dan Zawacki]

A good argument for interrupting the quench after a few seconds. Takes some getting used to, to be sure you've got your timing right, but it's really nice to be able to straighten things out before everything sets up.

 

[sunshadow]

Just make sure you are below the pearlite nose quickly enough!

-page

 

[Kevin R. Cashen]

In regards to Page’s micros, how much time or effort it takes to put carbon into solution depends on the coarseness of fineness of the structure the carbon is in before it is heated. The wider the spacing, the farther the carbon atoms will need to travel in order to be put into the austenite solution. Thus the longest soak times may be with very coarse spheroids, next would come very coarse pearlite, very fine spheroids would dissolve much faster, but very fine pearlite will also go into solution very quickly due to the very close lamellar spacing. This is why any coarse structure is bad if you can’t do proper soaks. The pearlite in Page’s micro looks rather fine and does not frighten me nearly as much as the large white patches forming a network around the grain boundaries. This is proeutectoid cementite and it is what the carbon above .8% makes when you allow it to cool too slowly from above “critical”. This is the stuff that will trash your drill bits, make your blade brittle and refuse to go back into solution even with a soak at normal quenching temperatures. The only way to get rid of it once formed is to totally dissolve it with good normalization heats. This is why 1095 is such a pain to so many smiths who don not make allowances for this characteristic of the steel, but once you realize it is there and know how to deal with it, you can turn in into a powerful ally instead.

Thank you Mr. Cashen. The part in bold...not sure I follow exactly, but I think I'll figure it out.

You first need to equalize, normalize and even everything out. This is done with a proper normalization heat which is hot enough to dissolve all the nasties and make everything one phase – austenite. Now DO NOT retard its cooling, as the first thing that will happen, if you allow it time, is that any proecutectoid carbon will come out of solution in coarse nasty structures, this is why ashes, vermiculite, or the warm forge is not a good idea for this steel. Allow it to air cool and retain that carbon in solution until it forms fine pearlite at around 1000F, when the magnet sticks the new phase has formed and you can reheat if you like. The next heat will refine the grain and the carbide structure by simply going to critical and then cooling; in your case you could quench in this heat in order to trap things in the finest solution for the spheroidal anneal in the forge. The blade will now be trapped in very fine solution but it will also be hard, so you need to soften it with some sort of annealing type operation. However, if you go above critical and stuff in the wood ash, vermiculite etc… not only will you form the unwanted coarse structures, you will undo all the wonderful refinement you have done so far, so we will use a special anneal, a sub critical anneal. Heat the blade to dull red, no hotter than say 1300F and allow the carbon to come out of solution in the form of countless superfine carbides. Do not allow the blade to lose magnetism or you will definitely have created austenite solution again and you will be back to square one on your annealing. Do this low temp heat a tow or three times and you should have a stress free blade with a very low HRC and an extremely fine structure that should be ready to kick over immediately on your quenching heat.

There, that should explain it all quite well for you and also allow others to take it all in for immediate use on their next blade without ever having to admit where they got the information. If need be the credit can be given to Bain, Grossman, Krause and others, all I did was verify that it worked for bladesmithing like it does with every other steel product. Isn’t knowledge wonderful?

 

[R.C.Reichert]

In regards to Page’s micros, how much time or effort it takes to put carbon into solution depends on the coarseness of fineness of the structure the carbon is in before it is heated. The wider the spacing, the farther the carbon atoms will need to travel in order to be put into the austenite solution. Thus the longest soak times may be with very coarse spheroids, next would come very coarse pearlite, very fine spheroids would dissolve much faster, but very fine pearlite will also go into solution very quickly due to the very close lamellar spacing. This is why any coarse structure is bad if you can’t do proper soaks. The pearlite in Page’s micro looks rather fine and does not frighten me nearly as much as the large white patches forming a network around the grain boundaries. This is proeutectoid cementite and it is what the carbon above .8% makes when you allow it to cool too slowly from above “critical”. This is the stuff that will trash your drill bits, make your blade brittle and refuse to go back into solution even with a soak at normal quenching temperatures. The only way to get rid of it once formed is to totally dissolve it with good normalization heats. This is why 1095 is such a pain to so many smiths who don not make allowances for this characteristic of the steel, but once you realize it is there and know how to deal with it, you can turn in into a powerful ally instead.



You first need to equalize, normalize and even everything out. This is done with a proper normalization heat which is hot enough to dissolve all the nasties and make everything one phase – austenite. Now DO NOT retard its cooling, as the first thing that will happen, if you allow it time, is that any proecutectoid carbon will come out of solution in coarse nasty structures, this is why ashes, vermiculite, or the warm forge is not a good idea for this steel. Allow it to air cool and retain that carbon in solution until it forms fine pearlite at around 1000F, when the magnet sticks the new phase has formed and you can reheat if you like. The next heat will refine the grain and the carbide structure by simply going to critical and then cooling; in your case you could quench in this heat in order to trap things in the finest solution for the spheroidal anneal in the forge. The blade will now be trapped in very fine solution but it will also be hard, so you need to soften it with some sort of annealing type operation. However, if you go above critical and stuff in the wood ash, vermiculite etc… not only will you form the unwanted coarse structures, you will undo all the wonderful refinement you have done so far, so we will use a special anneal, a sub critical anneal. Heat the blade to dull red, no hotter than say 1300F and allow the carbon to come out of solution in the form of countless superfine carbides. Do not allow the blade to lose magnetism or you will definitely have created austenite solution again and you will be back to square one on your annealing. Do this low temp heat a tow or three times and you should have a stress free blade with a very low HRC and an extremely fine structure that should be ready to kick over immediately on your quenching heat.

There, that should explain it all quite well for you and also allow others to take it all in for immediate use on their next blade without ever having to admit where they got the information. If need be the credit can be given to Bain, Grossman, Krause and others, all I did was verify that it worked for bladesmithing like it does with every other steel product. Isn’t knowledge wonderful?

Thanks for taking the time to explain all that Mr. Cashen! I'm sure many people will appreciate it, not just myself.

 

[Nathan the Machinist]

:thumbup:

 

[Alpenjodler]

Hi,
I ran into similar problems with 1095.
After unsuccessfully trying to controll the heat with a forge I decided to build my own heat treating kiln for less than $300.- and I love it!
The controller is a PID from Auber,
one Kanthal heating element (rated 2300 deg f) 1500W @ 110V is plenty for a chamber to treat knifes with. (12"x4.5"x6")
16 light fire bricks and a S30.- air tank from sears that I cut up for the housing does the trick.
I'm planning to post some pictures.
Good luck