On Monday, July 16, 2018 at 9:44:48 AM UTC-4, Ignoramus22929 wrote:
On 2018-07-16, wrote:
On Monday, July 16, 2018 at 8:43:05 AM UTC-4, Ignoramus22929 wrote:
On 2018-07-16, Gunner Asch wrote:
On Sun, 15 Jul 2018 21:28:36 +0100, David Billington
wrote:

On 15/07/18 18:57, Ken Grunke wrote:
Does anyone know what type of stainless steel is generally used for common butterknives? They seem to have the same temper as carbon spring steel, as I can't bend them. Looking for guidelines on heat treating, as I want to hot-forge the handles to make jaw harps, and might have to restore the blade's temper for springiness of the tongue.

Stainless cutlery is generally 18 -8, 18% Cr, 8% Nickel so 304. It can't
be heat treated to harden it only by mechanical working.


Correct.

Check them with a magnet, as most cutlery knives, in my experience, were 400 series
stainless and magnetic as iron.

That won't tell you what you think it does. This simple question actually is, unfortunately, pretty complicated to answer.

Once 300-series stainless has been heavily cold-worked, as in forging or coining, it's very magnetic. All of my flatware is highly magnetic and it's all 300-series steel.

400 series is used mostly for cutlery that needs to take and hold an
edge, not for table flatware.It's less rust-resistant. Leave a
400-series knife in lemon juice or vinegar for a day or two, and
you'll probably see what I mean.

I do not know what is more or less prevalent. Most spoons, forks and
knives that I saw were made of 400 series stainless. The reason for it
is that 400 series stainless is cheaper. But I am sure that I mostly
see cheap stuff.

Kitchenware manufacturers often use old steel designations, which
complicated the issue. However, for out purposes, their 18-8 and
18-10 designations are equivalent to 300-series austenitic
stainless. Almost all of your flatware is made of these grades. But
put a magnet on them -- most of them are magnetic from the cold
working. (Technically, they are "paramagnetic." They're attracted to
a magnet, but they can't be magnetized themselves to any substantial
degree.)



The only piece of 300-series stainless in my kitchen drawer that is
NOT magnetic is an ice cream scoop. My guess is that it was annealed
somehow, because the scoop has a pretty deep draw in it and thus is
quite heavily cold-worked.

While we're at it, cutlery manufacturers sometimes use the
designation 18-0. That's 400-series stainless, which is quite
magnetic. But they don't use it for flatware.

I just chedked the spoons that I have here at my work, they all jump
on magnets like iron would. I am a scrapper and I can tell.

Ken may have drawn some incorrect conclusions from what we've
said. For example, making a simple bend isn't going to contribute
much to work-hardening his stainless. Also, heating to 400 deg F
won't "anneal" his steel. If you soak it at the temperature for an
hour or so, you probably will get some stress relief. But it takes a
temperature over 1000 deg. F (aroun 1400, I think) to anneal
300-series stainless.


Let's let Oneida gum up the issue further for us. Get a load of this quote from their Amazon page:

"Constructed with 18/0 stainless steel, our housewares flatware is durable and stylish€¦and built to last for generations. In quality gauge and finish, Oneida housewares flatware represents the best of the category. Fine flatware is no longer only a special occasion item in the home€¦you will see it grace the dining table for everyday use in many homes across the country. Styles range from formal to casual, but all offer the highest level of craftsmanship. All Oneida fine flatware is 18/10 or 18/8."

....Tilt.... d8-)

Checking a manufacturer of restaurant-grade flatware did NOT clarify anything.

I'd love to track this down, but nobody pays me to do that anymore. Meantime, the old metallurgy books from which I got more of my information say that flatware is made of 18-8. Now I'm finding sources that say 18-0 (AISI 420). There even is some 13-0 (AISI 410).

I quit. I can't allow this much distraction from serious...um...fishing. d8-)

--
Ed Huntress