Nitro V post heat treat

T

Technohedge

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Sep 9, 2018
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Hi guys, Im progressing with my kitchen knife build for my sisters wedding present, I decided to make some others out of the left over steel. These have all gone off for a heat treat and should be back this week.

Couple of questions regarding finishing:

How careful do I need to be about ruining the temper with this steel when I grind? One of the knives still has a bit of stock to take off (belt went blunt and didnt have replacement) so how easy is it to wreck the hardness? I dip in water every pass.

Also how far down do you take the edges in terms of thickness (full flat grind) before switching to the sharpener?

Thanks! Will send pics soon
 
With blunt belt you risk to much ....... Get new belt , ceramic one.............If you are not careful it is easy to ruin blade even with new belt , not with blunt one :)
 
If you are not burning your edges prior to heat treat you should be good.

I do all bevel grinding post heat treat and for most knives do this... (KMG 3 speed) high speed for 36-80 grit, medium for 80-120 grit and slow for finishing.

I'd go to as near zero on the edge as you feel comfortable with.
 
Use a fresh belt, wet every pass, don't wear gloves and you should be fine. Just pay carefull attention to the tip, it can overheat quickly, as can the edge the closer you get to zero. Nitro-V is very nice to grind post heat treat. I do everything post heat treat, mostly Nitro-V and aeb-L. I grind in the tip section first on thinner knives ( kitchen knives and filet knives). Then, once the tip is at the thickness I want, I go back and do the rest of the bevel, blending it into the tip. This both keeps the tip from deflecting once you start to introduce distal taper, and provides a full thickness blank to better sink the heat from the tip.
 
Kevin McGovern said:
Yes, if you look at it as an issue .
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I find it to be a big issue. It's a pain to straighten at 300 degrees. I have had some luck with straightening off of the quench plates but have had it come back on the grinder. I'm still going to use thicker stock for outdoor knives but am pretty much going to S35VN for kitchen use.

If someone has a magic bullet to fix the problem I would love to know it.
 
I guess I'm used to dealing with it. I keep it clamped to quench and also through cryo and tempering. I never grind post heat treat .
 
Technohedge said:
Hi guys, Im progressing with my kitchen knife build for my sisters wedding present, I decided to make some others out of the left over steel. These have all gone off for a heat treat and should be back this week.

Couple of questions regarding finishing:

How careful do I need to be about ruining the temper with this steel when I grind? One of the knives still has a bit of stock to take off (belt went blunt and didnt have replacement) so how easy is it to wreck the hardness? I dip in water every pass.

Also how far down do you take the edges in terms of thickness (full flat grind) before switching to the sharpener?

Thanks! Will send pics soon
Click to expand...
10-20 thousands depending on use of knife. I make Culinary knives.—————-I do all grinding post HT. AEB-L & Nitro-V. Fresh Ceramic belts, water dip as you mentioned and I only bring the tip 1/4-1/3th into or across the Platen, that’s your thin spot where you can do damage.
 
Kevin McGovern said:
I guess I'm used to dealing with it. I keep it clamped to quench and also through cryo and tempering. I never grind post heat treat .
Click to expand...

This. Out of the plates, I keep it clamped all the way until I temper for the second time. From what it sounds like, the cold shock from dry ice or cryo causes a lot of the warping to occur. So its important to have it clamped during those stages.
 
That might make sub zero more attractive than LN for these steels. I also am switching to drilling post HT since I get bends at all of my holes.

I might be doing something wrong as well since I notice that sometimes I see lines from where the foil touches and that is causing problems. I think its from the foil packet puffing up and one spot getting good contact with the plate before I get the clamps tight.
 
Storm W said:
That might make sub zero more attractive than LN for these steels. I also am switching to drilling post HT since I get bends at all of my holes.
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Unfortuntely, I don't have a dewar yet to do cryo, but I would have to agree that putting a clamped piece of steel and angle iron into the tube may not be the easiest. I have only been doing sub zero for my AEB-L and Nitro-V. Retainted austenite aside (I can't analyze it), I have been very happy with the performance. How will you be drilling the holds post HT? Carbide?


Storm W said:
I might be doing something wrong as well since I notice that sometimes I see lines from where the foil touches and that is causing problems. I think its from the foil packet puffing up and one spot getting good contact with the plate before I get the clamps tight.
Click to expand...

What rating is your stainless steel foil? How are you cleaning the blades before they go into the stainless envelope? I am using the 309 foil and I haven't had issues with sticking, or welding of the foil and knife steel. The blades slide right out of the envelope once it's been cut open.
 
It's puffing up because you're putting something into the foil. It should do the opposite and be sucked onto the blade like a vacuum as the oxygen inside gets consumed. Using plate quench the blade comes out straight as an arrow.
 
My blades came back from heat treatment, most had warp.

The metallurgist said to me i can straighten them with a ball peen hammer if tap on the inside of the concave bend.

I wasn't happy doing his so I have sent them back for another go at tempering while clamped. Is there any info I can give the guy about Nitro V specifically that may aid in his processing?

Pic below of the trail run of the knife, this will become a set of home kitchen knives for us :)

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Thanks
 
When you say "metallurgist" exactly what is this person's heat treating experience? I know metallurgists who know a ton about metals, but could't harden water in a deep freeze.
 
Ok blades came back from the heat treat shop. The guy there said he managed to peen them straight. Interesting technique (picture below if anyones interested) looks like its been tapped repeatedly on the side with the concave bend. Seems to have straightened them out nicely!

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