stainless steel heat treating

[baggins]

Hi guys,

over the years i have made a fair few blades from 01 steel (a few of you even have one). Now, i've been given a small amout of 316 stainless steel, 4mm thick, and i fancy having a go at making a new blade out of it. I've heard though that stainless is very tricky to heat treat correctly, especially using the living room gas fire and the kitchen oven.
Does anybody have any ideas/guidelines for treating this steel or will i have to get it sorted by a proper smithy?
Cheers

Baggins

 

[HillBill]

I'm unable to give an answer mate, i'm going to be watching this though as i have been wanting to do the same thing for some kitchen knives.

 

[Draven]

http://www.azom.com/details.asp?ArticleID=2868#_Heat_Treatment

According to that, it cannot be hardened by heat treatment. Sorry mate! Not sure why though that is though... I can't vouch for the site, either.

The general consensus on stainless, though, seems to be that you need a temperature controlled oven to properly harden it, as the margins are just too slim.

 

[C_Claycomb]

Sorry mate, but you bin had.

316 cannot be heat treated. It is an austenitic stainless steel, work hardening.

http://www.aalco.co.uk/technical/stainless.html
http://www.aalco.co.uk/technical/datasheets/Aalco_Datasheet_St_St_316.pdf

And Azom is good info, we trust it, as far as it goes, in an aerospace company.

In addition to the temperature controlled oven, or salt pots, you really need to do something to protect stainless from de-carb, most use stainless foil, which is expensive, and hard to get in the UK. Many stainless steels then need a cryo treatment to get the most from them. Oh, and lastly, most are noticeably harder to grind than O-1, even the so-called "easy" grades. I am currently trying some 12C27, and that seems to be grinding alright, about like O-1, but without the sparks, but that is on a 36grit ceramic belt, so I don't know how it will finish. ATS34, which is noted for being easier to work than some of the CPM steels, was a lot harder to grind and finish! I would not envy anyone trying to file any of them.

 

[HillBill]

So are there any of the stainless variants that can be HT/tempered at home?

I think i read somewhere that 440 could be done, don't hold me to that though

 

[C_Claycomb]

I believe that some people have tried heat treating 440C in a forge, but you would have to trawl through the US forums for that info. I know I read about it once, but can't remember whether the results were acceptable.

Lots of people HT stainless at home....they just all have Paragon or Evenheat ovens!

Personally I wouldn't bother trying without the right gear. The steel is too hard to get, too expensive and too much of a pain to work with to go and mess around with dodgy heat treating. For me anyway. Given that you would really have to experiment, as you do even with O-1, to find out what works for your own kit. That starts to get pricey with imported steel.

 

[HillBill]

I believe that some people have tried heat treating 440C in a forge, but you would have to trawl through the US forums for that info. I know I read about it once, but can't remember whether the results were acceptable.

Lots of people HT stainless at home....they just all have Paragon or Evenheat ovens!

Personally I wouldn't bother trying without the right gear. The steel is too hard to get, too expensive and too much of a pain to work with to go and mess around with dodgy heat treating. For me anyway. Given that you would really have to experiment, as you do even with O-1, to find out what works for your own kit. That starts to get pricey with imported steel.

Thanks Chris. Might not bother then unless i can get someone to HT it.

 

[Mesquite]

Lots of people HT stainless at home....they just all have Paragon or Evenheat ovens!

So folks use thermostatically contolled kilns to heat treat the steel then Chris?

Just wondering as I have such a beast in my garage that I use for glass fusing so if you did want to play round trying it you can have a go in my kiln.

 

[C_Claycomb]

Cheers Steve,

Yeah, that is pretty much the kind of thing that they use. I also don't know whether the typical glass workers kilns do all the ramp ups as needed by steel . I have a couple of friends who have bought the posh blade treating ovens and both have spent quite a bit of time working out a process for each steel that they use. It wasn't simply a matter of reading a couple of temperatures off a recipe card and going for it with a blade. I think that Longstrider did something like a dozen test pieces on O-1 to be certain he got the cycle right.

As I said, I have some 12C27, which needs cryo, and some RWL34. In both cases I think I have routes to get it treated professionally. I don't have enough, or the patience, to try to work out how do do it right myself. I haven't even asked my friends with the ovens to do it. They aren't familiar with those alloys. If I owned an oven myself I might be more tempted to experiment, but space and cash constraints mean its all just wishful thinking for the moment!

 

[baggins]

Cheers Guys,

Glad my bit of ss was just an off cut from work. Looks like i'll stay with 01 for now. Be interested to hear of any results anybody has though with experimenting with mini ovens etc.

Baggins

 

[Shinken]

Yes if you manage to get hold of martensitic stainless in actual knife making sizes i would get it done by a company.

Most require a soak time at high heat which causes it to decarburize (doesnt happen when vacuum treated)

And they usually require cooling at a specific rate. or it goes wrong

 

[seved]

I have a friend that tryed HT AEB-L in a forge but it didnt go well. You have to have so high temp 1050_1080 C mostly and then hold it there for 10 min, thats why its so hard and most of the CPM steels you have to preheat the blades and hold it there for 10-15 min and then go on to HT temp.

Drvrf