Sharpening 12c27m

[Andybrock]

I've made a couple of chefs knives out of 12c27m which I'm having trouble getting a good keen edge.
My process was as follows
Coat blades in condursal z1100
Heat to 1080c hold for 5 mins quench in oil
Temper 2 x 1 hours at 170c
Grind bevels etc
I then tried to sharpen at 18 degress with little succes there were a couple of areas along the blade that just wouldn't burr.
Tried to resharpen at 20 degress with a little more sucess but again I can't get the blade no where near as sharp as I can blades made from 01.
Anyone see any problems with my procees or do anything differently?
Any help would be greatly appreciated.

 

[DevinT]

You might need a lower austenitizing temperature if there is no sub-zero or cryo quench.

I highly recommend you make several test coupons and see what brings the highest hardness at what temperature.

You are probably getting large amounts of retained austenite.

Hoss

 

[Andybrock]

You might need a lower austenitizing temperature if there is no sub-zero or cryo quench.

I highly recommend you make several test coupons and see what brings the highest hardness at what temperature.

You are probably getting large amounts of retained austenite.

Hoss

Thanks for taking the time to reply Hoss, how many degrees would you suggest to raise the temperature? If I did 5 pieces at 10 deree intervals would that be enough to make a significant difference.
Thanks
Andy

 

[DevinT]

Thanks for taking the time to reply Hoss, how many degrees would you suggest to raise the temperature? If I did 5 pieces at 10 deree intervals would that be enough to make a significant difference.
Thanks
Andy

Yeah, I test every 25’f from 1900’f - 2000’f. You’ll find the best temperature to harden from. Cryo would be the best way to attain maximum hardness.

Hoss

 

[Andybrock]

Yeah, I test every 25’f from 1900’f - 2000’f. You’ll find the best temperature to harden from. Cryo would be the best way to attain maximum hardness.

Hoss

Im going to test some later on today, is the 5 minute soak long enough or should I increase that also?
Sorry for all the questions, first time using stainless.
Thanks

 

[DevinT]

It depends on your furnace and blade or coupon size. It won’t hurt to go a little longer but will hurt to go too short.

Hoss