On Monday, July 16, 2018 at 10:49:33 AM UTC-4, Joseph Gwinn wrote:
On Jul 16, 2018, Ignoramus22929 wrote
(in ):

On 2018-07-16, wrote:
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 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-)

haha


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-)

Take a magnet to Walmart or bed Bath or whatever.

There is nothing really wrong with 400 stainless flatware, it cleans
well and you can eat soup with it just fine. But the look is not as
nice as 300 series.

I suspect that this clears up a mystery for me: I noticed that some spoons
imparted a metallic test while eating soup or chili, a taste like that of
carbon steel.

I bet I can taste the 400-series steels, but not the 300-series steels.

Joe Gwinn

Get a patent on the Joe Gwinn Lick Test. You could set yourself up as a metallurgy lab and have people send you samples for testing -- $20 a lick. d8-)

--
Ed Huntress