First time using 440C

clemsonreeder

clemsonreeder

Joined
Sep 25, 2007
Messages
176
Guys I am going to be making a few knives from 440C, and I haven't used stainless for making knives up to this point. Do I have any hope of heat treating it properly at home with just my small forge (no substantial accuracy in maintaining temp)? I'm figuring I'll have to send it out or find someone in the lowcountry with the proper set up. Anyone in South East SC on this site?
 
Stainless steel needs to be wrapped in SS foil and done in a H/T kiln as the have to be held at temp. for 30 min. plus. I do mine at 1880 deg. for 35 min.
Texas Knfemaker supply will do them for about 5 buck a blade.
Stan
 
If you're only making a handful, it's far easier and you will get better results by sending the blades to TKS, Paul Bos, etc for heat-treating. I wouldn't even try to HT stainless cutlery steel in a forge, and none of the pro's here has ever recommended it (that I know of.)

If you intend to make a bunch, a good kiln will eventually pay for itself in the shipping costs you save.
 
You may be able to do it in a forge if you can hold temps to plus or minus 10 deg. it will have to be wrapped in SS foil or the decarb will be very bad. Also you must maintain temps for 35-40 min.I have never tried it but if you put a muffle in your forge and can hold temps it might work.
Stan
 
I used a lot of 440-C back a few years. I sent it out to a company that heat treated it in a vacuum chamber and gave it the deep freeze nitrogen treatment as well. I thought it strange when I read in the forums that someone was heat treating it with a torch and hardening it in oil. They wrote that this way of doing it came from a very well known maker. I never did try it. Interesting though. Frank
 
i have heat treat a cheap stainless steel 1.4116 in a coal forge, but I covered it with clay for fireplace to avoid decarb. It works actually. I made 4 knives like that. Yellow collor is what I looked for. With the clay on it I use interrupted oil quench, and it worked. It comes out clean after I remove the clay. I tempered in a kitchen oven - 57HRC. Nothing is imposible if you remove the minus factors - decarb and oxidation. Of course you risking to burn the steel, because that is very high temps. I will show you a defect burned and melted blade after my first try to heat naked blade in the fire up to yelow colour. After that every time I add clay on.
Now I have electric digitally controlled HT oven, and those days are gone. But I still use clay and interupted oil quench.

Frank, hardness may occur on 800C-900C, but it may rust. 1000-1050C temps are for connecting chrome in the steel and make it stainless. That's atleast what a HT specialist that HT food processing knives told me.
Also some folks here told me that 30 min soak is not needed. 4-5 minutes at austenizing temperatue will be enough for the quenching. 30 minute soaks were for big and/or thick details to avoid cracking. Is that bullshit or not, and why?

DSCF2971.jpg
 
Last edited:
knifemaniac said:
i have heat treat a cheap stainless steel 1.4116 in a coal forge, but I covered it with clay for fireplace to avoid decarb. It works actually. I made 4 knives like that. Yellow collor is what I looked for. With the clay on it I use interrupted oil quench, and it worked. It comes out clean after I remove the clay. I tempered in a kitchen oven - 57HRC. Nothing is imposible if you remove the minus factors - decarb and oxidation. Of course you risking to burn the steel, because that is very high temps. I will show you a defect burned and melted blade after my first try to heat naked blade in the fire up to yelow colour. After that every time I add clay on.
Now I have electric digitally controlled HT oven, and those days are gone. But I still use clay and interupted oil quench.

Frank, hardness may occur on 800C-900C, but it may rust. 1000-1050C temps are for connecting chrome in the steel and make it stainless. That's atleast what a HT specialist that HT food processing knives told me.
Also some folks here told me that 30 min soak is not needed. 4-5 minutes at austenizing temperatue will be enough for the quenching. 30 minute soaks were for big and/or thick details to avoid cracking. Is that bullshit or not, and why?

DSCF2971.jpg
Click to expand...




I know that this was addressed to Frank, but I may be able to help here.
From my understanding, The reason for the higher temps and longer soak time is to get everything possible into solution, so that it can form the most desirable structures. This is especially true with chromium, the element most responsible for making a steel stainless. The higher the chromium content the higher the temp and the longer the soak. You may be able to get some hardness and stain resistance from using lower temps and shorter soak times, but you will not realize the true potential of the steel.
Hope this helps,
Del
 
knifemaniac said:
i have heat treat a cheap stainless steel 1.4116 in a coal forge, but I covered it with clay for fireplace to avoid decarb. It works actually. I made 4 knives like that. Yellow collor is what I looked for. With the clay on it I use interrupted oil quench, and it worked. It comes out clean after I remove the clay. I tempered in a kitchen oven - 57HRC. Nothing is imposible if you remove the minus factors - decarb and oxidation. Of course you risking to burn the steel, because that is very high temps. I will show you a defect burned and melted blade after my first try to heat naked blade in the fire up to yelow colour. After that every time I add clay on.
Now I have electric digitally controlled HT oven, and those days are gone. But I still use clay and interupted oil quench.

Frank, hardness may occur on 800C-900C, but it may rust. 1000-1050C temps are for connecting chrome in the steel and make it stainless. That's atleast what a HT specialist that HT food processing knives told me.
Also some folks here told me that 30 min soak is not needed. 4-5 minutes at austenizing temperatue will be enough for the quenching. 30 minute soaks were for big and/or thick details to avoid cracking. Is that bullshit or not, and why?
Click to expand...

I did that, mom uses my first D2 knife for 5 years... BUT after I bought proper HT equipment I was like WOW... Right after my first temperature controlled kiln HT I was convinced that I was unaware of the potential of that steel and I really dont recommend to try to HT a high alloy on a forge. You won't be able to hold the temp even and unchanged for 40 mins on a forge. Its OK to try but I wouldnt recommend anyone to rely on eyeballing the forge temps for stainless steels. Also it is not a must for thin stock to hold at temp about 40 mins, I've had good results with 20-25 min soaks. But even with the thinnest knife a soak under 20 mins is not recommended, you have to give some time for the carbides to dissolve, otherwise you wont have decent result...
 
As far as the soaks, it disolves the carbides (chromium carbide in this case) and evens out the temperature. It also evens out the distribution of chromium and other alloying elements, which were previously concentrated in the carbides. See Kevins thread on Hypereutectoid Steels.

For the higher temperatures for stainless in general, remember that chromium is a ferrite stabilizer. The more chromium, the higher the temperature required to form austenite at all. It has a pronounced effect even in steels like 5160 and 52100.
 
You must log in or register to reply here.
Back
Top