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Should stainless steel be annealed?


#1

I’ve never worked with stainless steel but have decided to give it a
try. It seems like a fun alternative to silver, given its current
high cost, but with a nice silver-like look–I know some folks have
sensitivities to nickel. I’ve searched and found a lot of information
regarding the steps I think I’ll need: etching (with ferric
chloride), soldering with black flux and silver solder, pickling with
regular pickle but best separately, and various patinas for
finishing. I plan to form in my press with silhouette dies.

But what about annealing? Should the metal be annealed to a soft red
or a cherry red? And what about quenching? I don’t know the
difference between the types of stainless but Metalifferous has a 23
gauge ‘type 300’ in stock, so I’ll be using some of that.

Any other tips regarding using stainless will also be appreciated.

Thanks, Mary


#2

Stainless steel refers to a family of iron alloys that have enough
chromium in them to provide a passive chrome oxide surface that
resists corrosion leaving the surface bright over a wide range of
conditions. The 300 series stainless steel alloys also have nickel
in them the basic percentage of chrome - nickel is 18-8 and often you
will hear them referred to as 18-8 stainless. They are way harder
then silver and will take much greater force to form. The chrome
oxide will make it difficult to get solder to flow so you will need
a good flux, the black flux or a good white fluoride based flux. You
will find that the black oxide that forms when heating the stainless
is very tough to remove. A strong acid is typically needed to pickle
it ferric chloride can also help in this regard.It work hardens very
fast, to anneal the 300 series you need to heat to 1700-1800 F then
quench in water. It will never get real soft though. Unless you are
using tool steel silhouette dies you may find it is going to be hard
on your dies. after cutting, filing, soldering etc you will need to
re-passivate the surface for it to regain its “stainless” properties
a final pickle in citric acid will do this. Stainless is definitely
challenging to work with but can take on a nice polish and is very
durable.

James Binnion
James Binnion Metal Arts


#3

Mary,

I work a lot with 304 stainless steel with 18kt yellow gold overlay.
First, you can’t anneal stainless steel and if you heat it to high
it turns black and is difficult to clean. Your next problem to solve
is what solder or braze to use on stainless. I’ve found that using
silver brazing wire with stay brite flux works best for me, you’ll
have to experiment because silver solder and gold solder won’t work.
The great thing about 300 series stainless steel is it will not
tarnish or wear out from constant use as jewelry. If you want to
make a ring I’ve found that finding different size stainless tubing
works best, because trying to size it won’t work without using a TIG
welder to weld the seam. I’ve never tried to etch stainless although
I engrave it using hammer and gravers made of Momax Cobalt.


#4
First, you can't anneal stainless steel 

That is total nonsense, of course you can anneal it. 304 anneals at
1700 F followed by a water quench.

and if you heat it to high it turns black and is difficult to
clean. 

This is quite true but ferric chloride or hydrochloric acid pickle
will remove it, they also will etch the stainless so care is needed
to clean it.

Your next problem to solve is what solder or braze to use on
stainless. I've found that using silver brazing wire with stay
brite flux works best for me, 

Are you are referring to StayBrite solder? If so it is a low temp
solder composed of tin silver and will bond to stainless but it has
a very low melting temperature and is not really suitable for fine
jewelry.

you'll have to experiment because silver solder and gold solder
won't work. 

They both work fine for me, there is a type of silver solder that is
specifically designed for stainless that contains 2 % nickel. Use of
this silver solder will reduce chances of cracking in the brazed
area. Gold solder also works fine on stainless. You just need to use
a quality paste flux like handy flux or black flux.

James Binnion
James Binnion Metal Arts


#5

Jim,

First, you can’t anneal stainless steel

That is total nonsense, of course you can anneal it. 304 anneals
at 1700 F followed by a water quench. 

There are ferritic alloys which do anneal at lower temps, but 304 is
not one of them. 304 is an austenitic steel and needs 1900F. That temp
of 1700 F is more in line with a soaked stabilizing anneal follwed by
a water quench for other SS alloys, which I might add, normally comes
after a conventional anneal of 1900 F.

Best Regards.
Neil George


#6

Neil,

There are ferritic alloys which do anneal at lower temps, but 304
is not one of them. 304 is an austenitic steel and needs 1900F.
That temp of 1700 F is more in line with a soaked stabilizing
anneal follwed by a water quench for other SS alloys, which I might
add, normally comes *after* a conventional anneal of 1900 F. 

The 1700 is from one of the data sheets I have on 304, I have seen
the 1900 and 1800 also cited. When I anneal it I set my furnace for
1750 and see a significant softening. But I have not done any
metallography to see if I actually see recrystallization. As you
probably know the annealing temperature for any metal varies
depending on the amount of cold work it has received. The greater
the amount of cold work the lower the annealing temp required to
induce recrystallization. I also use a ferritic stainless that
anneals at 1400 F so as you point out it does depend on the alloy.
For engineering uses the processes we use to heat treat and anneal
for jewelry are no where near adequate but usually work out ok for
our needs. But I certainly would not want to trust my life to a
component heat treated in a typical metalsmith studio :slight_smile: mine
included.

James Binnion
James Binnion Metal Arts


#7

Jim,

The 1700 is from one of the data sheets I have on 304, I have seen
the 1900 and 1800 also cited. When I anneal it I set my furnace
for 1750 and see a significant softening. But I have not done any
metallography to see if I actually see recrystallization. As you
probably know the annealing temperature for any metal varies
depending on the amount of cold work it has received. The greater
the amount of cold work the lower the annealing temp required to
induce recrystallization. 

I have no doubt that at the 1750F temperature there would be at
least a noticeable difference in the hardness and workability of the
material, however it does more harm than good in some cases at least
at the industrial level. As you pointed out, in jewellery, not such
a big deal. Having said that, to maintain the anti corrosive
properties, 304 requires the raised 1900F temp.

I also use a ferritic stainless that anneals at 1400 F so as you
point out it does depend on the alloy. For engineering uses the
processes we use to heat treat and anneal for jewelry are no where
near adequate but usually work out ok for our needs. But I
certainly would not want to trust my life to a component heat
treated in a typical metalsmith studio :-) mine included. 

You’re right, at the industrial level, where other dynamics come
into play, it’s critical to get it right. Part failure can be a life
or death situation in many cases. This is why I send out all of my
heat treating requirements and get them qualified :slight_smile:

I do suspect though Jim, that your documentation although stating an
anneal, is referring to a stabalizing anneal used after welding.
Especially on 304L. They even use the term anneal, for stress
relieving which is in the 750-1100F range. Go figure. Drives me crazy
when people throw out terminology without a second thought of how it
will reflect on the process :slight_smile:

Best Regards.
Neil George


#8

should it? sure if you want to modify it’s shape…it’s tough
stuff.

I’ve had very good results using silver solder on stainless 304
tubing and flat stock.

After soldering I “pickel” by electrostripping with citric acid
(courtesy of here on orchid)

Need an expensive power supply you ask? No, Use a standard cordless
tool 18 volt battery as your power supply.

Run a copper wire through a short hard plastic handle of some kind.
Take the copper wire through the middle of

a scotch brite pad and secure the pad on the handle. This lead wire
goes to the negative side of the battery.

Most of the time you don’t even need the pad, but it can be used to
scrub stubborn oxides.

Go from the positive battery terminal to an alligator clip. Connect
it to the work piece being stripped.

In a suitable container, have enough citric acid solution to
submerge the article being worked on.

place the work piece in the citric acid with the alligator attached.
it’ll bubble.

citric acid is available at some markets ( for cooking) or on the
’net.

works like magic to remove oxides… but best practice is to AVOID
getting the

black oxides by using a good flux - florided flux works best for me,
but i strictly use a vent hood on HIGH when i do it.

stainless polishes like chrome with bobbing, rouge, and zam. each
step makes it shinier!

the ring shanks i’ve made seem really rugged, impervious to daily
wear by a harsh user.

Good hand strength is required to make ring shanks from flat
stock… even using “ring bending” pliers it’s

bend, anneal, hammer, and go again and again till you get it
smooth… white gold solder provides the best color match.

steve

about electrostripping the stainless…

I almost forgot about passivating…

let the work piece sit in a warmed bath of the citric acid for 20-30
minutes…then rinse with water.

Without passivating, the stainless surface remains "electrolically"
active: the surface can react

with chemicals and oils/salts from skin… may happen or may not…
but it’s an easy step.

  • credit goes to Bob Edwards at Chromis Designs for the info*.

it all worked great for me.
steve


#9
I do suspect though Jim, that your documentation although stating
an anneal, is referring to a stabalizing anneal used after welding.
Especially on 304L. They even use the term anneal, for stress
relieving which is in the 750-1100F range. Go figure. Drives me
crazy when people throw out terminology without a second thought of
how it will reflect on the process :-) 

Yes I am in agreement here. I did some more looking around and the
1700 F number seems below the others I have found. The ASM handbook
lists 1850-2000 F for the annealing range for 304. And I totally
agree about critical tools and parts being professionally heat
treated. I send critical stuff out, especially after I a had high
tonnage press die I heat treated fracture and scare the !@#& out of
me. No one hurt but many hours of machining time lost, cheaper to
have it done right.

Regards,

James Binnion
James Binnion Metal Arts