Without an oven or salts, I would say you have to use vermiculite or another insulator like ash. I have a covered metal bucket of fine wood ash with all bits of charcoal strained out. I wouldn't think that the three cycles from 1275 to black air cooling on the 1084 would act as an anneal. It's my understanding that you need a much slower cooling rate for the anneal, hence the need for an insulator. But I am a novice and could be completely wrong. <img src=' http://www.americanbladesmith.com/ipboard/public/style_emoticons//smile.gi f' class='bbc_emoticon' alt=':)' />

Steve. personally I do thermal cycling right after forging, one at 1600, the next at 1500, then a sub critical at 1300 or so. I do not quench then. I bury the blade in vermiculite and let it cool overnight. I do not have a salt bath. After I do the pre heat treat grinding I will do another thermal cycle at 1500 and cool till black. Then I quench.

Wood ash or lime will also work.

You might want to check out Kevin's website for additional information.

Kevin Cashen bladesmithing info

Brion

For what it is worth, I do have salt baths and do not use them for most normalizing or annealing operations, it would not be very practical, efficient or economical, so I use my kilns instead. Be aware that the subcritical anneal is not absolutely necessary for the 1084, but is for the W2. In fact in the 1084 you will not get many speroidal carbides of any great size, but you should get a lot of them with the W2, and if you don’t the form the carbide remains in can give you grief.

With rampable kilns soaking at 1375F before cooling at a rate of less than 50F per hour is the most thorough way to spheroidized. Without such a kiln heating to 1275F, but not more than 1300F, (dull red but keep the magnet sticking) should ball up your extra carbides. All of the real work is done from 900F to 1275F so there is no great need for insulating on the cool. Heck all the of the real work in traditional annealing is done in the same range so once the steel is lower than 900F there is no reason for a slow cool there either. In fact some industrial processes rapidly cool to the correct range and then once the desired effects are obtained the steel can be quenched to room temp and immediately worked, but that requires exact temperature control.

Kevin, would you recommend the same when working O-1?

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Kevin, would you recommend the same when working O-1?

O-1 almost necessitates spheroidizing (aka sub critical anneal), in fact if I were going to machine it I would do nothing less than a full industrial spheroidizing.

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Steve. personally I do thermal cycling right after forging, one at 1600, the next at 1500, then a sub critical at 1300 or so. I do not quench then. I bury the blade in vermiculite and let it cool overnight. I do not have a salt bath. After I do the pre heat treat grinding I will do another thermal cycle at 1500 and cool till black. Then I quench.

Wood ash or lime will also work.

You might want to check out Kevin's website for additional information.

Kevin Cashen bladesmithing info

Brion

Brion,

Do you do the process above on both 1084 and W2? I was thinking that the thermal cycling had to be in the higher ranges for the W2....but I'm not sure why.

It's good to hear of someone using vermiculite from a subcritical anneal--I thought vermiculite was used for the slow cool only from higher temperatures (Again, I'm not sure why I thought that either).

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For what it is worth, I do have salt baths and do not use them for most normalizing or annealing operations, it would not be very practical, efficient or economical, so I use my kilns instead. Be aware that the subcritical anneal is not absolutely necessary for the 1084, but is for the W2. In fact in the 1084 you will not get many speroidal carbides of any great size, but you should get a lot of them with the W2, and if you don’t the form the carbide remains in can give you grief.

With rampable kilns soaking at 1375F before cooling at a rate of less than 50F per hour is the most thorough way to spheroidized. Without such a kiln heating to 1275F, but not more than 1300F, (dull red but keep the magnet sticking) should ball up your extra carbides. All of the real work is done from 900F to 1275F so there is no great need for insulating on the cool. Heck all the of the real work in traditional annealing is done in the same range so once the steel is lower than 900F there is no reason for a slow cool there either. In fact some industrial processes rapidly cool to the correct range and then once the desired effects are obtained the steel can be quenched to room temp and immediately worked, but that requires exact temperature control.

Kevin--thanks for jumping in. I was pretty comfortable with the 1084 heat cycling since you and several others helped me work it out in an earlier thread. The W2 cycling I lifted from the hamon thread, but the subcritical anneal step I couldn't do because I don't have an oven.

So, are you saying that a good substitute for the oven soak and slow oven cool to 900 (50 F/hour) anneal is to heat to 1275 F and then air cool? Should I do three cycles, like with the 1084?

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Kevin--thanks for jumping in. I was pretty comfortable with the 1084 heat cycling since you and several others helped me work it out in an earlier thread. The W2 cycling I lifted from the hamon thread, but the subcritical anneal step I couldn't do because I don't have an oven.

So, are you saying that a good substitute for the oven soak and slow oven cool to 900 (50 F/hour) anneal is to heat to 1275 F and then air cool? Should I do three cycles, like with the 1084?

Multiple cycles can work if you are not able to hold for any ammount of time.

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1084

1. Normalize: 1600 F and air cool

2. Thermal Cycling: once to 1500-1475 F with air cool, once 1450-1475 F with oil quench, 3 cycles from 1275 to black cooling in air.

Steve,

On the 1084 only...

The 1600F normalize made all grains the same size... bigger than ideal but equal in size. Stepping down the temperature for the next normalizing cycle kept the grains equal in size and made them smaller. Quenching after the next step down in temperature (third normalizing cycle) had the grains equal in size and smaller yet.. AND added a large amount of strain to all the crystals. 3 cycles at 1275 is a "jack shaft" spherodize anneal.

If you had skipped the quench after the third normalizing cycle you would have ended with grains small enough to advantage a knife blade and a piece of steel that was soft enough to grind, file, drill, and sand easily.

Annealing by cooling from above critical at a very slow rate will always cause grains to be large. Large grains are not the end of the world for a knife, but they don't have to be that way and it takes less time to make grains small and have steel (of eutectic carbon level and less) soft enough to work by normalizing three times, than to do a slow-cool anneal... (what do you call that kind of annneal, Kevin?)

Mike

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...Annealing by cooling from above critical at a very slow rate will always cause grains to be large. Large grains are not the end of the world for a knife, but they don't have to be that way and it takes less time to make grains small and have steel (of eutectic carbon level and less) soft enough to work by normalizing three times, than to do a slow-cool anneal... (what do you call that kind of annneal, Kevin?)

Mike

The actual technical term (and that recognized in industry) is "lamellar annealing", in simple carbon steels because it produces lamellar structures (pearlite). It does not necessarily have to produce coarse grain but it does have to produce grain size equal to that induced by the higher austenitizing temperature (how high that is is a matter of choice). So long as the grain coarsening temperature is not exceeded grain growth is solely a matter of temp and not time. What a lamellar will unavoidably do is create coarse carbide, which can be worse than grain size, depending how it is arranged and whether you can break it up again. Hypereutectoid steels will make large lamellar sheets and carbide networks when cooled slow from above critical. Spheroidizing tends to isolate the carbide into fine spheroids and obviously is well below anything that could even effect grain size.

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The actual technical term (and that recognized in industry) is "lamellar annealing", in simple carbon steels because it produces lamellar structures (pearlite). It does not necessarily have to produce coarse grain but it does have to produce grain size equal to that induced by the higher austenitizing temperature (how high that is is a matter of choice). So long as the grain coarsening temperature is not exceeded grain growth is solely a matter of temp and not time. What a lamellar will unavoidably do is create coarse carbide, which can be worse than grain size, depending how it is arranged and whether you can break it up again. Hypereutectoid steels will make large lamellar sheets and carbide networks when cooled slow from above critical. Spheroidizing tends to isolate the carbide into fine spheroids and obviously is well below anything that could even effect grain size.

Thank you, Kevin...

Mike