Treating Stainless, do you include multiple hold times??

Lerch

Well-Known Member
I was wondering if when heat treating like 154CM you include more than one hold time? Like if your desired heat treating temp was 1950deg for 45min would you first have a say 15min soak time at 1400deg and then proceed to the final soak temp??

I thought i had read about this, maybe people calling it a stabilizing cycle or something but i can seem to find any writing about it now that im looking for it lol

just wondering if this was real or if i dreamed it up. if it could be worth while or if it would promote undo grain growth???

thanks
steve
 
Some makers do - the idea being to let the part equalize - catch up with the oven temp a bit. While it is often recommended by spec sheets, they likely refer to thicker sections. Something as thin as a knife blade probably doesn't require it. There are well respected knife makers on both sides of the discussion. I might feel differently if my kiln was very fast, but taking 45 minutes to get from cold to hot -I think the blade can pretty much keep up.

One of the makers that does do an equalizing pause is Ed Caffrey. I'm hoping he'll chime in with his thoughts on the matter.

Rob!
 
Yes. The steel companies refer to it as "equalizing", and I feel it's a necessary step in the heat treat process. In my experience, if the equalizing "soak" isn't used, the end blade turns out significantly more brittle.

For the steel you mentioned (CPM154), I equalize at 1425F for 30 mins, ramp to 1950F and hold for 30 mins......then plate quench, and temper 3X @ 650F
 
A lot goes on in a steel when it is heated and different things are happening at different temperatures. Also carbides of metals like tungsten need a higher soak austinizing temperature to release it's carbon into solution. Heating the steel to between the upper and lower critical temperatures as you would do with a simpler hypereutectic alloy just won't do the trick. An intermediate soak at just above lower critical, or even below it if that's the manufacturer's recommendation, may not be necessary with something as thin as a knife blade but I don't see where it's going to hurt anything either. I'd go with Ed's recommendation even if it was just to stay on the safe side of things.

Doug
 
Okay, thanks guys,

Ya equalizing is the word i was looking for lol, i knew i heard it before. Thanks Ed for the info, im all for doing anything I can to better refine the steel or ensure a tougher blade in the end

thanks !!

Steve
 
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