Right now I am working with thinner steel which is easy to get up to critical temp. I ordered some thicker blade stock but haven’t used it yet. I mostly work with 15n20, and 8670. If a blade that is .103 thick reaches critical temp in 3 minutes how much longer should a blade that is .125 thick take before it reaches critical temp. I am using a coal forge and judging the steel by its color. Thanks
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Heat treat question
- Thread starter TheEdge01
- Start date
- Joined
- Nov 4, 2015
- Messages
- 30
Going from .103 to .125 thickness in a coal forge should make a negligible difference. They would likely reach the target temperature seconds apart, all things being equal.
The bigger issue is that all things aren't likely equal. It's easier to have one coal fire hotter or cooler than the last. The overall size of the stock (length and width as well as thickness) also plays a huge role, as the more material you have, the more energy it takes for the entire target area to reach a relatively uniform temperature, and the more opportunity there is for the non-heated parts to "wick" away heat from the blade itself. For example, a 12" long, 4" wide bladed chopper with a 6" by 2" handle is going to take a lot longer to heat than a small skinner, and while it will hold heat longer, even at the same thickness, it will lose it from parts less uniformly than the skinner will. The middle may stay within a few hundred degrees of your target temp for upwards of 20 seconds, while the outer edges may be back to black after just 10.
In my experience, it's better to judge by color and magnetism than time if you're heat treating in a forge, and color uniformity trumps exact target temperature, within reason. I'd rather have a solid cherry red blade, even if it ended up being slightly lower than the ideal temperature, than one with some parts orange, some cherry, and some parts still dull red. Generally, that means a lot of moving the blade around to keep it even, but I find it to be a fun challenge.
The bigger issue is that all things aren't likely equal. It's easier to have one coal fire hotter or cooler than the last. The overall size of the stock (length and width as well as thickness) also plays a huge role, as the more material you have, the more energy it takes for the entire target area to reach a relatively uniform temperature, and the more opportunity there is for the non-heated parts to "wick" away heat from the blade itself. For example, a 12" long, 4" wide bladed chopper with a 6" by 2" handle is going to take a lot longer to heat than a small skinner, and while it will hold heat longer, even at the same thickness, it will lose it from parts less uniformly than the skinner will. The middle may stay within a few hundred degrees of your target temp for upwards of 20 seconds, while the outer edges may be back to black after just 10.
In my experience, it's better to judge by color and magnetism than time if you're heat treating in a forge, and color uniformity trumps exact target temperature, within reason. I'd rather have a solid cherry red blade, even if it ended up being slightly lower than the ideal temperature, than one with some parts orange, some cherry, and some parts still dull red. Generally, that means a lot of moving the blade around to keep it even, but I find it to be a fun challenge.
Thank you!!! I’ve been making blades since last November, needless to say, it has been and is continuing to be quite a learning experience.Going from .103 to .125 thickness in a coal forge should make a negligible difference. They would likely reach the target temperature seconds apart, all things being equal.
The bigger issue is that all things aren't likely equal. It's easier to have one coal fire hotter or cooler than the last. The overall size of the stock (length and width as well as thickness) also plays a huge role, as the more material you have, the more energy it takes for the entire target area to reach a relatively uniform temperature, and the more opportunity there is for the non-heated parts to "wick" away heat from the blade itself. For example, a 12" long, 4" wide bladed chopper with a 6" by 2" handle is going to take a lot longer to heat than a small skinner, and while it will hold heat longer, even at the same thickness, it will lose it from parts less uniformly than the skinner will. The middle may stay within a few hundred degrees of your target temp for upwards of 20 seconds, while the outer edges may be back to black after just 10.
In my experience, it's better to judge by color and magnetism than time if you're heat treating in a forge, and color uniformity trumps exact target temperature, within reason. I'd rather have a solid cherry red blade, even if it ended up being slightly lower than the ideal temperature, than one with some parts orange, some cherry, and some parts still dull red. Generally, that means a lot of moving the blade around to keep it even, but I find it to be a fun challenge.
Heat it up to 3000’ and quench it in liquid nitrogen.
Oh wait, what was your question?
Critical temperature is different than austenitizing temperature. In general, the more alloy in the steel the longer the soak time.
This doesn’t answer your question, just some thoughts after reading your post.
Hoss
Oh wait, what was your question?
Critical temperature is different than austenitizing temperature. In general, the more alloy in the steel the longer the soak time.
This doesn’t answer your question, just some thoughts after reading your post.
Hoss