1095 soak

If it stays at austenitization temp and does not go over that (controlled oven), the time is not much of a worry. Most folks soak 1095 for 5-10 minutes. If it went 20, I doubt it would grow all that much larger grains. Longer time might be a problem.
 
1095 does not have alloying that O-1 or other steels may have so it does have one less safeguard against grain growth, but there are still others in place. Keep your soak temp around 1475F and no higher and you should not have to worry. Get above 1475F and grain growth will not be your only worry, overheating hypereutectoid steels can quickly increase retained austenite to annoying levels, as can over-soaking at the wrong temps. It would really be best to stick around 1475F for 5 to 10 minutes.
 
I'm glad you chimed in on this one Kevin - this one was right up your alley.

...that damn fickle 1095 again...
 
do you even need to soak simple steels? I know many many many makers do not even bother.
 
It depends on the condition of the steel. The heats it has had leading up to austenitizing will dictate where the carbon is, and what it will need to go into solution.

According to the stickies, if the 1095 has lots of fine carbides that are broken up and evenly dispersed (you set it up for HT properly) it will go into solution without a very long soak. If the carbon is tied up in great big plates of carbide, it is going to take a while - but that won't be your only problem. I think that Kevin did a wonderful job of explaining all of it in the stickies.

I'm not sure there is a single simple answer.
 
I heat treated a W1 blade today and soaked it at 1500 for about 20 mins. and quenched in warm oil. Do I have big problems then....? (BTW....tempered at 475 2x for 2 hrs each time)

Brad
 
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Kevin explains it all in the stickies.

No, you don't have a big problem, but you probably don't have the finest grain. If you want finer grain, well your long soak at 1500 should have the carbon evenly dispersed. So a couple thermal cycles and re austenitize and you'll be good to go, if you're concerned about it.
 
petah said:
do you even need to soak simple steels? I know many many many makers do not even bother.
Click to expand...


The appeal to popularity is one of the most common errors that bladesmiths make in their reasoning for methods, many, many bladesmiths also forego a mask when grinding but the numbers don’t lend legitimacy to the habit, heck most of them are still kicking and looking pretty healthy, but...;)

However, having said all that, it will all depend on the steel. Eutectoids (.8% carbon) and hypoeutectoids (below .8% carbon) will not display as much of a difference without a soak, but hypereutectoids (above .8% carbon) will more quickly display issues arising from improper solution at temperature. You will get a more drastic drop in hardness from tempering and some effects on both strength and toughness and precise temperature control becomes more important. For every degree higher you go your time decreases much faster that you would think until minutes turn into seconds and fractions of seconds and then the margin for error vanishes, so the safest way to do a hypereutectoid steel is lower and with a soak.

The reason most folks wouldn’t see a problem with hypoeuctectoid steels, like 5160, without a soak is that the damages of overheating are less pronounced and so it better survives just getting it hot in the forge and quenching.
 
B.V. said:
I heat treated a W1 blade today and soaked it at 1500 for about 20 mins. and quinched in warm oil. Do I have big problems then....? (BTW....tempered at 475 2x @ 475 for 2 hrs each time)

Brad
Click to expand...

I hope I can help but I am not understanding all of your process, I am unable to find "quinching" in any dictionary and I get the feeling it is not a typo.
Do you have hardness numbers on the resulting blade? W1 should be kept at around 1475F as well. There is a pretty good chance of more than normal retained austenite, and perhaps some grain size issues but that is not for certain. I would definitely want to know the hardness before the temper before going to 475F.
 
Theoretically,... how about giving it a good long soak at a lower temp., say around 1450, and then bumping it up real quick to about 1500 just for a minute or two? Of course, you'd need a furnace that would respond quickly enough... a gas or charcoal muffle of some sort maybe, that could easily be bumped up 50-100 degrees in a minute or less...

... just an idea I've been toying with.
 
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I have heard of going the other way....from 1500 for a short soak then down to 1400 for a bit pior to quench.

Brad
 
I believe that would undo the benefits of the soak to a noticable degree, and you would end up a lot of pearlite. The idea is to get an homogenized solution of carbon with the iron, then lock it place with the quench. Soaked at much below 1475°, the solution will begin to break down with the carbon trying to reform into clusters, or possibly plates, instead of being evenly distributed in the iron. Where did you here that?
 
Well, rather than go into detail about those involved in the discussion.....I will attempt to explain the idea as it was presented (although as usual my part in the discussion was that of the guy who doesn't know anything :). The idea was to get the carbon into solution, lower the temp some prior to quench so that part of the cooling was already done before the trip to the quench tank. This was in an effort to try for a hamon. That's about as good as I can do with a lack of technical savy......
 
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