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Need some specific hardening / tempering information - any help appreciated!

Hello all,

I ran across some 430 stainless steel in the scrap bin at work today, and there was just enough on the margins to cut a couple of sets of woodturning chisels, so I took the opportunity to make them.

They're all cut to shape, the flutes are pressed and they're welded to stainless ferrules, so they're almost ready to go- but they are annealed for sheet work, so they're obviously going to need some hardening.

Basically what I know, or at least can guess at, is that I need to heat them past critical, then quench in *something*, give them a little polishing to remove any scale and then reheat to temper some of the brittleness out. None of that should be a problem with the forge I've got set up, but I want to make sure to get it right- as high(ish) carbon stainless is pretty hard to come by in the shop I work at.

So, what I'm looking for is a ballpark on the temp I need to heat these to, what I should quench them in (water and brine are immediately availible, and motor oil is obviously easy enough to come by- unfortunately, another guy is waiting on one of the sets, so I really don't have a lot of time to mail order any special qunching oil unless it is *absolutely* required) Is this project going to want a slow dip in the quenching fluid, point first, or a full immersion very quickly and all at once? I am also wondering how hot they need to be for how long to temper them. There are eight of the suckers, so an ideal situation would be if I could perhaps temper them in the (kitchen) oven on the regular racks.

The parts are 14" long from ferrule end to chisel tip, with 13" flutes. The flute material is .114" thick, and has a 2A finish, if that matters. The blanks were laser cut from sheet stock that is known to be resistant to warping under welding heat. Their intended application is to shear spinning wood with a tool rest supporting the flute about 1/4" to 3/4" from the cutting edge. The most important thing for me is to get the keenest edge I can out of these without them being so brittle that they crack under normal usage. (I know 440 would have been better, but this was free and redily availible, so it's worth a try!)

Thanks for any advice you might have!

Reply to
Prometheus
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Machinery's Handbook says that 430 is "not hardenable by heat treatment". Its carbon content is 0.12%. 440 has a carbon content of

0.60 -0.70%, in contrast. Interestingly, to me, is that 403, 410, 414 and 416, with carbon contents of only 0.15% are listed in a table with other stainless steels that ARE called hardenable!

Pete Stanaitis

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Prometheus wrote:

Reply to
spaco

I wonder if Superquench would do anything.

- ken

Reply to
Ken Rose

I haven't looked up the data, but you really can't do stainless at "home". It needs very precise heat temps for longish periods of time. I.E. digitally controled furnace. Than to get the most (or anything) out of those alloys the need to be cryo-treated too.

If ya gotta make something out of stainless, farm the heat treating out.

sorry, I'm pretty sure your hosed.

matthew ohio

Reply to
MatthewK

No kidding...

Well, that's what I get for not looking it up in advance, I guess. I was going off the naming convention for steel and assuming that 430 was .30% carbon and 440 was .40% carbon. Both seemed a little low for edged tools, but it's an alloy.

Well, in their current state they do take a pretty keen edge- maybe they'll work as is, though I'm guessing they'll dull really quickly. I'll try that superquench stuff and see how that goes, too.

Reply to
Prometheus

Maybe superquench would work, but you don't hear of Chromium-bearing steels being even water quenched. 5160 (used for car springs), for example, is an oil hardening steel as far as I know. We have demonstrated (for our students) water quenching some other tool steels that are air or oil hardening and the results are often disastrous. Things crack and distort. Some are sensitive enough that even hardening them "properly", without enough normalizing after forging, begets the same problems.

Try work hardening some of the stock with a hammer. See what happens. Some stainless steels even workharden while drilling or otherwise machining them.

Pete Stanaitis

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Ken Rose wrote:

Reply to
spaco

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A quick scan of the article talks about normalizing and quenching at lower temperatures. The author is refering to refractory coated blades too.

matthew ohio

Reply to
MatthewK

All that Cr in there makes the measly .15%C feel;)like it's been subjected to "super" super-quench. :)

Cr slows everything up including the "spitting out" of the C by the Fe.

But the trick is to heat it high enough and for long enough to make the Cr let go of the C and let it get sucked;)into the Fe before you quench it.

Many of those stainless steels are age and precipitation hardened and in practice many are just work hardened and not Q&T.

It's crummy ol' stainless steel... it'll dull quickly even if it's

440C with a cryo-quench. ;)

Alvin still bad mouthing stainless steel in AZ

Reply to
alvinj

I'll give that a try, and possibly attempt a slow controlled heat. From what I found, it is reputed to become brittle after prolonged exposure to temps in the 400-600* range. I'm sure brittle does not necessarily mean hard, but I may as well try hardening some of it that way by pulling it out of the oven every so often and skating a chisel across it. Probably can't hurt, and may do the job to some degree.

The real solution for this is likely to be the one I decided on today- I ordered a 20' bar of 1095 through work (and am currently anticipating that "just got punched in the belly" feeling I'm sure to experience when I find out how much that is going to set me back!), and will likely end up making exotic handles for the stainless pieces, and mount those pretty "chisels" on the wall of the turnery as decoration and make another working set with the right material (that is, the right carbon steel material- tool steel is out of budget range for sure!)

Reply to
Prometheus

And, by the time one does all the heat treating it's not even stainless any more until passivated. (And that's no guarantee. -- and not to mention it forges like hitting a brick.

I helped one of my students who just _had_ to try to make a fantasy sword out of 2-1/2 feet of 1" X 2" 440C. Damn near killed both of us, but he ended up with a nicely shaped, HUGE sword blank! I think he's still grinding on the sumbitch.:)

We were hitting it as hard as we could with my Precision Adjustment and Fitting Tool (8-pound sledge with 18" handle) and it was hard to move at any color. OUCH, my arm aches just remembering it!

440C is a much better stock removal steel than forging steel. To say I don't like it would be a prize-winning understatement.
Reply to
John Husvar

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