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Gerhard Gerber

14C28N

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This is my first foray into Stainless, might as well since I got the digital kiln...

First heat treat went well, only complaint is both blades have a bow in them.  The stock I bought was slightly bent in transport (I guess), but I straightened the two pieces I started with.

My problem is the following, while doing my "research" I'm sure I read about plate-quenching 14C28N, so at considerable expense I went and bought two suitable 30mm plates.

On the day I went to check the exact temperatures and hold times, and all I can find on the Sandvik site mentions oil quench.....?

I might be confused, most likely am, but since I found out that without a cryo cycle I won't get this steel over 60 HRC, so I was wondering if a plate quench might not be sufficient and solve some other problems as well.......

If any of you regularly use this alloy, I would appreciate some pointers or advice.

Thanks

Gerhard

PS: going by the hand sanding the two blades are plenty hard.....and I got them straight.

Edited by Gerhard

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I haven't used it (and hopefully never will, or any stainless for that matter).  So I can't help with personal experience.  

But I trust you were looking at this page from Sandvik.  

How the hardening parameters affect the product properties

  • Too high hardening temperature gives low hardness and bad wear resistance due to excessive content of retained austenite.
  • A low hardening temperature gives low hardness and reduced corrosion resistance.
  • Too long holding time at the optimal hardening temperature increases the amount of retained austenite and lowers the hardness.
  • Too short holding time at the optimal hardening temperature has the same effect as low austenitizing temperature.
  • The maximum hardness will be obtained at a retained austenite content of about 15%.
  • Deep freezing, i.e. cooling to below room temperature, increases the hardness by about 1–2 HRC.
  • With deep freezing, the highest possible hardness will be achieved by increasing the hardening temperature. Read more in the Sandvik hardening guide.
  • High cooling rate after hardening is necessary to avoid brittleness and reduced corrosion resistance. 600°C (1112°F) should be reached within 1–2 minutes and room temperature within 30 minutes.
  • Rehardening is generally not recommended as it will not give optimal product properties.

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11 hours ago, Jerrod Miller said:

I haven't used it (and hopefully never will, or any stainless for that matter).  So I can't help with personal experience.  

But I trust you were looking at this page from Sandvik.  

Indeed.

I treated a 5160 blade first so the kiln was at about 830C when they went in, hoping that meets the 600C under 2 minutes requirement......thing blades so.....

Worked on a timer exactly on spec, my blade thickness is between their last two options so I soaked for 17 minutes IIRC.

@Jerrod Miller I would appreciate even a guess from you.....

Would chucking the blades in the deep freeze actually help or are we talking dry ice type situation here?

Considering I'm quenching in garden variety Canola oil, do you think the plate quench is worth a try?

Unfortunately no easy access to a Rockwell tester....

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21 hours ago, Jerrod Miller said:

I haven't used it (and hopefully never will

Why is that? If I'm ever going to use stainless, this seems like the stainless steel that behaves closest to carbon steel. Easy to grind and polish, low carbide volume, fine grain, good hardness, takes a keen edge and excellent toughness. Of course, this is all based on feedback I've read...

@Gerhard Gerber

Most makers use plate quench on this steel because it has a tendency to warp. An oil quench would only make it worse.

Edited by Joël Mercier
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Gerhard,

The freezing is to convert the retained austenite.  As indicated from Sandvik, your soak temperature and cooling rate will determine the amount of retained austenite.  The more you have, the colder you are likely to need to go to convert it all.  I guess the real question is whether or not that 1-2 HRC and a little more impact toughness is worth the effort to you (austenite is not good with impact toughness).  Cooling to 600 C in a minute should be pretty easy.  You could probably even throw it between your plates and toss the assembly in the oil to cool.  

Joël,

The applications where stainless is pretty much a requirement are very few.  Pretty much just salt water environments (boaters and divers).  Given that situation, knives are at a greater risk of being lost (overboard).  As such, all the complications in production do not seem worth the effort for a custom knife, and those that are willing to pay for it won't be asking me -- they'll find someone MUCH better at knife making.  I'd recommend those applications to at least consider the knife as a consumable.  Buy a decent production knife, and when needed, replace it.  Any knife I make I expect to be well cared for, so simpler alloys will serve nicely.  

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4 hours ago, Joël Mercier said:

Why is that? If I'm ever going to use stainless, this seems like the stainless steel that behaves closest to carbon steel. Easy to grind and polish, low carbide volume, fine grain, good hardness, takes a keen edge and excellent toughness. Of course, this is all based on feedback I've read...

@Gerhard Gerber

Most makers use plate quench on this steel because it has a tendency to warp. An oil quench would only make it worse.

You sure you're not thinking of 13C26, Sandvik's version of Uddeholm AEB-L?  That's the one I have my eye on for those things that absolutely positively have to be stainless.  Devin Thomas loves the stuff, which is recommendation enough for me.  Of course, gotta get a heat-treat kiln first.

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34 minutes ago, Alan Longmire said:

You sure you're not thinking of 13C26,

Those are very similar. The one with added nitrogen (14c28n) has a bit higher working hardness and even better corrosion resistance because the nitrides fill every tiny pores in the steel.

Aldo's version(nitroV) is even better so I've heard...

Edited by Joël Mercier

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@Joël Mercier Thank you for confirming about the plate quench, so I stick to the Sandvik recipe? 

@Jerrod Miller Well both blades went flying at some point and hit cement tip first, they are plenty tough, so not worth the effort I guess.

 

12 hours ago, Jerrod Miller said:

The applications where stainless is pretty much a requirement are very few.  Pretty much just salt water environments (boaters and divers).  Given that situation, knives are at a greater risk of being lost (overboard).  As such, all the complications in production do not seem worth the effort for a custom knife, and those that are willing to pay for it won't be asking me -- they'll find someone MUCH better at knife making.  I'd recommend those applications to at least consider the knife as a consumable.  Buy a decent production knife, and when needed, replace it.  Any knife I make I expect to be well cared for, so simpler alloys will serve nicely.  

I've asked that question here before, and from the answers I could only conclude that many of you are lucky to have such educated clients.

My mentor is Swiss, lives and makes knives here in deepest darkest Africa, sells to tourists staying at their tented camp as well as regular international customers.  He switched exclusively to stainless following too many complaints about rusting knives when the people get back home.

He lives in the desert, rust is not an issue.

It took a very strange set of circumstances for me to buy a digital kiln, but I have it now and that's opened the door to SS.

The two steak knives I made and the kitchen knives I have on order are all headed to people who would not know better.

 

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