Boronizing your blades at home?

[zoe-pae]

Hi everyone, I'm new here and don't know much about this forum. Up until now, I've just been browsing through topics a bit, lurking around and learning more about knives and blades.

However, now I've been wondering if there is a way to harden your blades at home? Specifically boronizing them since I've been reading a bit about its advantages. I'd really love to do this so my kitchen knives will practically last forever. If anyone knows anything about this topic, lemme know!

 

[danbot]

Hi everyone, I'm new here and don't know much about this forum. Up until now, I've just been browsing through topics a bit, lurking around and learning more about knives and blades.

However, now I've been wondering if there is a way to harden your blades at home? Specifically boronizing them since I've been reading a bit about its advantages. I'd really love to do this so my kitchen knives will practically last forever. If anyone knows anything about this topic, lemme know!

Welcome!
Do you have an oven that can reach at least 1800 degrees Fahrenheit? That's one thing you'll need....

Edit to add link: http://www.metlabheattreat.com/boriding-boronizing.html

 

[zoe-pae]

My grandpa has an old furnace in his garage, which I think I could use. He told me that he has melted aluminium in that furnace back when he was younger (and I believe aluminium has a melting temp of around 600 celsius). But in my research I think I read that 1000°C would suffice? It's written somewhere here IIRC https://bortec.de/en/ Which is the correct number? 1000 or 1800?

EDIT: Nevermind, I mixed up the units! 1000°C = 1800°F for those who didn't know

 

[danbot]

Cool! Do some experiments! But I think you will run into problems when it comes to knives. You will need to resharpen after boriding and you will need to ensure that the penetration is sufficient as to not just get completely removed from sharpening.

Give it a go and let us know how it turns out.

Edit: Safety first! If you obtain the stuff you need, make sure no one's gonna breathe that s*** in!!! Powdered elements + high temp + oxygen can also be extremely dangerous!

 

[Bill DeShivs]

At that temperature, you will completely ruin the heat treatment of the steel, and be completely relying on your treatment for proper hardness.

 

[NJBillK]

At that temperature, you will completely ruin the heat treatment of the steel, and be completely relying on your treatment for proper hardness.

For the OP, and to take this a bit further...

You would also have to:
- soak at temp (hold at accurate temperature)
- quench
- re-temper your knives
- remove some of the blade stock since you would now have a layer of decarb to deal with (a layer where the carbon has been burned out of the blade)
- decarb is not hardenable, so you will have to get back to "good" steel
- craft new handles
- finally sharpen your knives

If all of this is done correctly (mostly the soak, quench, and regrind), you will have about half of your work done.

Does this sound like the project you had in mind?

 

[danbot]

For the OP, and to take this a bit further...

You would also have to:
- soak at temp (hold at accurate temperature)
- quench
- re-temper your knives
- remove some of the blade stock since you would now have a layer of decarb to deal with (a layer where the carbon has been burned out of the blade)
- decarb is not hardenable, so you will have to get back to "good" steel
- craft new handles
- finally sharpen your knives

If all of this is done correctly (mostly the soak, quench, and regrind), you will have about half of your work done.

Does this sound like the project you had in mind?

And typical penetration of the boronizing is ~0.001"-0.015". So if you get full penetration and you grind off more than 0.015" then you have defeated the whole purpose.

 

[NJBillK]

And typical penetration of the boronizing is ~0.001"-0.015". So if you get full penetration and you grind off more than 0.015" then you have defeated the whole purpose.

So it would be entirely likely that the boronizing wouldn't penetrate deeper than the decarb layer. With decarb seemingly more prone to corrosion (on non-stainless knives) this would likely net a negative outcome?

- Is boronizing less prone to corrosion?

- With the decarb being softer, would one have to worry about the boronized layer being damaged from scratches penetrating through it, since it is on a softer substrate?

- If these are not legitimate concerns, one would only have to worry about tempering, cleaning up the edge and making new handles. (Still sizeable tasks for a beginner.)

 

[danbot]

So it would be entirely likely that the boronizing wouldn't penetrate deeper than the decarb layer. With decarb seemingly more prone to corrosion (on non-stainless knives) this would likely net a negative outcome?

- Is boronizing less prone to corrosion?

- With the decarb being softer, would one have to worry about the boronized layer being damaged from scratches penetrating through it, since it is on a softer substrate?

- If these are not legitimate concerns, one would only have to worry about tempering, cleaning up the edge and making new handles. (Still sizeable tasks for a beginner.)

I'm no expert on the subject, but we do a similar thing at work putting a ceramic coating on steel. it's actually pretty cool! But these processes were not at all developed with knives in mind. You would need to do some ultimately costly experimentation, and may well come to the conclusion that its just not feasible for knives.

With the Boronizing, I would first try just annealing the blade, then shoot for max penetration, sharpen and test. If you determined that a re-heat treatment was required, I would be very concerned with what was going to happen to that blade during the quench!
Maybe a steel like A2 would fair better.

 

[danbot]

Found some interesting stuff on the subject. This is an example of a "knife" for processing wood. So it is an industrial application.

This is a link to a patent for a boronizing paste. Its "self protecting" so it will work in a furnace without a controlled atmosphere.
http://www.google.com/patents/WO2008100155A1?cl=en