forging stainless and what steels to use?

[tormentchris]

I have a couple people that want some chef knives. I've done a little reading about forging stainless steel but I'd like to hear it from some people as well before I get started ordering steels and forging. I found a piece of steel in my shop (1" squared) that has no rust, oxidation, or frankly any discoloration at all. Most non-stainless steels will discolor a little bit from just sitting around in the shop after a period of time. Anyway, I digress. 440-c is a preaty common steel to use but how is it under the hammer? 154-CM is another but i've hearsd that it is very difficult for forge. I buy steel at Jantz and there is several different types and was wondering what would be the best to use. I plan on making a good hunting knife out of what ever I get too. With all that said, Any advise would be appreciated.

Thank, Chris

[tormentchris]

Also, I forgot to ask. I've heard that a clean coke fire is best for stainless. Does that mean that i can't use my propane forge and I have to use my coal forge? Do I need to buy some actual coke or can I just make some with my coal. It probably depends on what type of steel I'm forging with, huh? The coal I have cokes up really nicely. BTW

[Al Massey]

Not too many stainless alloys are great for forging and they tend to be really hard on abrasives after doing so because of the chromium oxides- you're essentially using abrasive to try and remove abrasive.

It's also problematic to heat-treat unless you have a proper furnace setup. That being said, there's no reason not to use stainless for knife-length pieces- but I see no real benefit to trying to hand-forge it unless you're working a particular curve.

Actually, I can't see why propane wouldn't be better than coke- no sulfur and such. I have forged stainless in propane and had no problems other than the ones mentioned. You have to remember most stainless air-hardens.

Edited March 8, 2015 by Al Massey

[tormentchris]

Not too many stainless alloys are great for forging and they tend to be really hard on abrasives after doing so because of the chromium oxides- you're essentially using abrasive to try and remove abrasive.

It's also problematic to heat-treat unless you have a proper furnace setup. That being said, there's no reason not to use stainless for knife-length pieces- but I see no real benefit trying to hand-forge it unless you're working a particular curve.

Actually, I can't see why propane wouldn't be better than coke- no sulfur and such. I have forged stainless in propane and had no problems other than the ones mentioned. You have to remember most stainless air-hardens.

so, doing 90% of the work hot is key?

[Doug Lester]

Many, if not most, of the stainless steels have a narrow working range. For 440C Jim Hrisoulas lists the starting temperature for forging to be 1900-2100° which would be a bright yellow. Forge lower than that and you risk having it crack on you. Hardening requires a soak at around 1900° though he doesn't say how long. I would think that it could be for several minutes which would indicate the need for a regulated oven. However I haven't found a data sheet that says for how long. Another problem is the fact that 440C is that it is air quenching. After each forging session the steel must be annealed. This can be approximated in a solid fuel or gas forge but you really need a regulated heat treating oven to do it right. 440C can be quenched in oil but I would recommend quenching in still air. I just don't favor quenching any faster than the steel calls for. You can temper this steel in a kitchen or toaster oven.

 

440C is also probably the least demanding of the stainless steels. More complex stainless steels not only have problems if forged too cool but many will crumble if forged too hot. They also can require long soaks at high temperatures. Basically, if your friend wants a stainless steel knife you should do it by stock removal and send the blade out to a professional heat treater for hardening and tempering.

 

Doug

[Al Massey]

The info I have on 440C says 30 mins. at 1850-1950 F, so unless you have a LOT more temp control than I do in my forge you really need a furnace. And you will want stainless foil- this stuff eats belts like no one's business with the scale layer- to wrap it in before the HT. Temper at 350 for a couple hours.

[Jerrod Miller]

Chef knives don't HAVE to be stainless either... L6 or 15N20 with a good polish will resist rusting pretty well (relatively speaking) and many chefs use plain carbon. You just have to be very nice to your knives and not leave them in the sink.

[tormentchris]

Cool, good stuff!!!

I'm starting to think this stainless thing is too much sugar for a dime. I know my buddy takes very good care of his kives. He's a professional BBQ and meat chef. That being said, I do think I'll go with a nice pattern welded steel with 15N20 included. Got to love that shine

[Brian C Madigan]

I can forge 1/2" or larger a bit by hand, but anything smaller than that is red hard after a few hammer blows. 1900-2500f is pretty hot. Bigger blocks are forged all the time in presses and power hammers of course because the mass holds the heat better.

If you want to go stainless:

Get 440c in 1/8 or 3/16ths and grind to shape. Heat treating requires a temp controlled oven that can hold at 1900f. I use an Evenheat electric oven.

You should foil wrap or use anti-scale compound that can handle that heat range (ATP-641 from brownells works for me).

 

I would never use stainless mystery steel. If you don't know the composition, its no good for making a blade!

[deker]

so, doing 90% of the work hot is key?

 

Or forging thick and using something very aggressive (angle grinder and cup stones!) to clean off the scale before going to the belt grinder. I try to de-scale everything before heading to a belt nowadays if I can. It's much nicer to the belts, and me.