Quench Patina?

N

nemosis

Joined
Jun 16, 2014
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I'm very new to all this, and just got my hands on some 80CrV2.

I quenched my first blade using this in Parks 50.

The hardness seems ok, but there is a charcoal grey patina that seems to go fairly deep.

I'm wondering is this just the wrong quench medium, was it quenched too hot, or something else?


Thank you
 
That’s called forge scale it is inevitable (Unless you use some sort of zero atmosphere heating method)
Grind/sand it off and your fine.
 
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Bunker Hill Blades said:
That’s called forge scale it is inevitable (Unless you use some sort of zero atmosphere heating method)
Grind/sand it of and your fine.
Click to expand...
Thank you for the reply.

It looks to be a little bit different from non-quench forge scale, and is a bit deeper on the 80CrV2 than other alloys I've quenched?

This is a little bit more grinding than other alloys.

I may have just made the world's first tactical-tanto steak knife?
 
Most likely it is decarb. You have to grind/sand it away. It is softer than the hard steel, so it removes pretty fast.
Decarb is a thin surface layer of steel that is depleted of carbon. It is different that forge scale, which is a hard layer of iron oxides.

Tuning the forge to a slightly reducing atmosphere when doing HT helps reduce decarb.
 
Thank you for the response and the information.

My burners are homemade, and while I didn't initially, I've been meaning to add a way to regulate air intake.

Guess this will finally be my impetus to do that.
 
Also, you can soak the knife in vinegar to remove the forge scale and save a bit of belt life from just grinding it off.
 
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Yes, and overnight soak in cheap white vinegar will remove forge scale and some of the oxides. The decarb will still need to be ground/sanded away, but it makes it a faster and cleaner process.

To make a good etching or vinegar soak tank, get a 24" piece of 4" PVC pipe, a closed foot plate (closet flange with test knockout), and a cap. Use PVC glue to attach the foot plate to the pipe. Close with the cap when not in use. Whole setup is less than $25. Works perfect for FC etchant, too. It holds 1 gallon of solution.
 
Stacy E. Apelt - Bladesmith said:
Yes, and overnight soak in cheap white vinegar will remove forge scale and some of the oxides. The decarb will still need to be ground/sanded away, but it makes it a faster and cleaner process.

To make a good etching or vinegar soak tank, get a 24" piece of 4" PVC pipe, a closed foot plate (closet flange with test knockout), and a cap. Use PVC glue to attach the foot plate to the pipe. Close with the cap when not in use. Whole setup is less than $25. Works perfect for FC etchant, too. It holds 1 gallon of solution.
Click to expand...
Awesome, thank you for the advice.

I have used FC, but when I have, I've used a water bath to warm it.

I repurpose the sous vide pump that I use similarly
 
nemosis said:
Awesome, thank you for the advice.

I have used FC, but when I have, I've used a water bath to warm it.

I repurpose the sous vide pump that I use similarly
Click to expand...
In a tub of water to keep my propane tank from freezing up at high outflow.

Will probably modify your design slightly to allow for that.
 
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