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MasterMaker
03-14-2011, 07:12 PM
I have some stainless plate and also some ground 20 and 25 mm rod that I'm thinking about making into knives, basically my own version of a COP tool(knife strong enough to be used for hacking/prying with a chisel point).

Unfortunately I don't know what kind of stainless it is so my question is are there any types of stainless that can't be hardened and tempered sufficiently to be used for a knife(and what are its common uses).

The plate is non-magnetic , the rod is magnetic and both the rod and the plate work harden.

PixMan
03-14-2011, 10:04 PM
As far as I know, only the magnetic stainless steels are heat-treatable. My experience is with 410, 420, 430, 440C, 17-4PH, 15-5PH and they all heat treat to different specs.

fishfrnzy
03-14-2011, 11:49 PM
The plate, not going to work. The magnetic bar might work. Cut a 1/4" thick piece and heat it until the magnet wont stick ( roughly med to bright orange ) Then quench in oil. Try to file it with something other that your best file, then you'll know. it still may not hold an edge like a 440C or one of the variants but will probably do what you want.

johnnyd
03-15-2011, 08:08 AM
Is it possible to "case harden" stainless?

Carld
03-15-2011, 09:31 AM
I think the SS that good knives are made from is 440. A SS would have to have as high a carbon content as you can find to hold an edge. I still prefer a high carbon steel knife blade but they are few and far between and never made in the style I prefer.

Personally I think SS knife blades suck and only high carbon blades are best.

pressurerelief
03-15-2011, 09:47 AM
If it is 316 stainless, introduce it to a machine tool and with the incorrect feeds and speeds and it will harden all by itself.

Jaakko Fagerlund
03-15-2011, 01:47 PM
What about tool steels that are stainless? ;) I don't remember any right now, but I can get back with a list of tool steels that could work.

MasterMaker
03-15-2011, 03:07 PM
Thanks for the answers.

I'm going to have to try to heat a slice of the ground bar and give it the file test and if it can get hard enough.

As I have quite a bit of the plate it looks like I will have to think of another use for it(I was having thoughts about a one piece axe), maybe a field shovel for the backpack.

Having done a bit of research it does look like one can case harden non magnetic ss but only to a depth of a couple of thousands of an inch.

Does anyone know how 304ss(what I assume the plate is) responds to Kasenite or a similar case hardening compound???

MrSleepy
03-15-2011, 03:34 PM
there are a couple of processes that can be used to case harden stainless steels


Kolsterising - a low temperature carburizing process for austenitic grades of stainless

Malcomizing - a nitriding process for all grades of stainless.


But Im not sure if you can do these yourself..

Rob

lazlo
03-15-2011, 04:54 PM
If it is 316 stainless, introduce it to a machine tool and with the incorrect feeds and speeds and it will harden all by itself.

I've forged 316. It's a bitch (not malleable at all), but it doesn't harden, at least not to knife standards.

In the commonly available stainless steels (assuming you don't happen to have sheets of ATS 34/BG-42 or CPM S30V around the shop :)), only 440 and the precipitation hardening stainless (17-4 et al) will harden enough for a blade.

MasterMaker
03-15-2011, 07:09 PM
How about 416?

Given what PixMan said about only magnetic SS being hardenable and the fact that the rod is magnetic I am hoping that it will harden sufficiently to make a PryKnife(will cut of a 5-6mm slice tomorrow and give it a heat and quench to find out if it is).

I think I read somewhere that the entire 300 series of SS can't be hardened and if PixMan is right about magnetic=hardenable I am hoping that it is something in the 400(possibly 416??)

Bear in mind that the knife I am making will have a blade that is 5-6 mm thick with a 30 edge angle(and a 60mm blade length/25mm blade width) so hard enough to hold an edge wouldn't have to be Rc60.

Ries
03-15-2011, 07:23 PM
If its nonmagnetic, most likely its 304. Which work hardens, but actually gets softer if you heat and quench.
The answer is, dont make a knife out of it- make a spoon.

This is 304, forged from a piece of 1 1/4" round, originally about 6" long. Now something like 20" overall. I made a fork to go with it, its an industrial scale salad set.
No welding, machining, or grinding. Just forged.

http://img.photobucket.com/albums/v132/rniemi/spoon.jpg

lane
03-15-2011, 07:48 PM
If a magnet want stick to it it wont harden. Period. No more need be said.

lakeside53
03-15-2011, 08:50 PM
How about 416?

Given what PixMan said about only magnetic SS being hardenable and the fact that the rod is magnetic I am hoping that it will harden sufficiently to make a PryKnife(will cut of a 5-6mm slice tomorrow and give it a heat and quench to find out if it is).

I think I read somewhere that the entire 300 series of SS can't be hardened and if PixMan is right about magnetic=hardenable I am hoping that it is something in the 400(possibly 416??)

Bear in mind that the knife I am making will have a blade that is 5-6 mm thick with a 30 edge angle(and a 60mm blade length/25mm blade width) so hard enough to hold an edge wouldn't have to be Rc60.


Some knife makers around here use 420... By far the cheapest way to buy the materials is a $13 chinese cleaver (420) and cut it down to whatever you want.

fishfrnzy
03-15-2011, 09:43 PM
If you have alot of the plate sell it at the scrap yard ans it is going for about $ .70-$1.00 per lb. If you have alot of it that will give you some cash to buy some material you want. 440C in round bar is pretty well available and can be forged. It is considered the "stainless" tool steel. D2 tool steel comes close with about 13% chrome content. Material is usually called stainless steel when the chrome content reaches about 13-15%. Stainless is really not "stainless" but it is corrosion reisisting ( CRES ) and resists corrosion to different degrees depending on environment, heat, and chemical composition. There are about 50 alloys of stainless plus all the nickel variations.

lazlo
03-15-2011, 10:14 PM
Some knife makers around here use 420... By far the cheapest way to buy the materials is a $13 chinese cleaver (420) and cut it down to whatever you want.

420 is a low carbon, low-end steel that has poor toughness and doesn't harden well. I've only seen it in cheap knives. A cheap Chinatown cleaver would probably fit that description.

It's not the style of knife either -- I've seen high-end, high dollar Chinese cleavers from Shun (Kershaw) et al in Hitachi White, 440C, S30V, etc.