Great idea. I do not think that 1/8" is too large. Feels about right
to me.

i

In article ,
Ignoramus24760 wrote:

Great idea. I do not think that 1/8" is too large. Feels about right
to me.

They look pretty robust. We shall soon see it 1/8" is the right size. The
first two skewers are out of the dishwasher.


A question for the welders out the Which SS alloys can be welded or hard
(silver) soldered without destroying the stainless property? I see lots of
advice to re-passivate SS items that have been heated to a red heat, to avoid
subsequent corrosion, but for many things I might make re-passivation would be
pretty awkward, and I don't think all SS alloys require this.

For instance, food service furniture is welded and silver brazed, but is far too
large to be dipped into a tank, and brush passivation is too slow.


Joe Gwinn

On 2010-09-04, Joseph Gwinn wrote:
In article ,
Ignoramus24760 wrote:

Great idea. I do not think that 1/8" is too large. Feels about right
to me.

They look pretty robust. We shall soon see it 1/8" is the right size. The
first two skewers are out of the dishwasher.


A question for the welders out the Which SS alloys can be welded or hard
(silver) soldered without destroying the stainless property? I see lots of
advice to re-passivate SS items that have been heated to a red heat, to avoid
subsequent corrosion, but for many things I might make re-passivation would be
pretty awkward, and I don't think all SS alloys require this.

For instance, food service furniture is welded and silver brazed, but is far too
large to be dipped into a tank, and brush passivation is too slow.


Joe Gwinn

Joe, this is bull****.

Do not worry about it. Itwill not rust through. I have a stainless
grill that is 10 years old and has seen a lot. The stainless on it is
stained, but is in perfectshape.

i

In article ,
Ignoramus31991 wrote:

On 2010-09-04, Joseph Gwinn wrote:
In article ,
Ignoramus24760 wrote:

Great idea. I do not think that 1/8" is too large. Feels about right
to me.

They look pretty robust. We shall soon see it 1/8" is the right size. The
first two skewers are out of the dishwasher.


A question for the welders out the Which SS alloys can be welded or
hard
(silver) soldered without destroying the stainless property? I see lots of
advice to re-passivate SS items that have been heated to a red heat, to
avoid
subsequent corrosion, but for many things I might make re-passivation would
be
pretty awkward, and I don't think all SS alloys require this.

For instance, food service furniture is welded and silver brazed, but is
far too
large to be dipped into a tank, and brush passivation is too slow.


Joe Gwinn

Joe, this is bull****.

No, it isn't. Depends on the alloy. Many stainless steel alloys will rust,
given the right excuse.

One thing that I'm finding in sellers of commercial-grade skewers is that Type
304 seems to be what they all use for SS, if they mention an alloy by number.
However, these items are never heated to incandescence, as would be needed
during hard soldering.


Do not worry about it. It will not rust through. I have a stainless
grill that is 10 years old and has seen a lot. The stainless on it is
stained, but is in perfectshape.

Yes, and so do I. But do you know which specific stainless steel alloy was
used? That's the question.

Joe Gwinn

On Sep 4, 1:12*pm, Joseph Gwinn wrote:

A question for the welders out the *Which SS alloys can be welded or hard
(silver) soldered without destroying the stainless property? *I see lots of
advice to re-passivate SS items that have been heated to a red heat, to avoid
subsequent corrosion, but for many things I might make re-passivation would be
pretty awkward, and I don't think all SS alloys require this. *


Joe Gwinn

Good question. The higher the chrome and nickel and the lower the
carbon if it is going to be welded. But I do not know about silver
soldering. The problem is that when heated high enough, the carbon in
the stainless combines with the chrome to make chrome carbides. And
that lowers the percentage of chrome so it no longer stainless. I do
not know if the temperature for silver soldering is high enough that
chrome carbides are formed. I also do not know that re-passivating
will help.

Found on the internet

If any part of stainless-steel is heated in the range 500 degrees to
800 degrees for any reasonable time there is a risk that the chrome
will form chrome carbides (a compound formed with carbon) with any
carbon present in the steel. This reduces the chrome available to
provide the passive film and leads to preferential corrosion, which
can be severe. This is often referred to as sensitisation. Therefore
it is advisable when welding stainless steel to use low heat input and
restrict the maximum interpass temperature to around 175°, although
sensitisation of modern low carbon grades is unlikely unless heated
for prolonged periods. Small quantities of either titanium (321) or
niobium (347) added to stabilise the material will inhibit the
formation of chrome carbides.

So the temperatures for silver soldering are high enough to cause
problems But the time at high temperatures would be less than for
welding. So I would expect stainless that is silver soldered to be
more corrosion resistant than stainless that has been welded.


Dan

In article ,
Joseph Gwinn wrote:

In article ,
Ignoramus24760 wrote:

Great idea. I do not think that 1/8" is too large. Feels about right
to me.

They look pretty robust. We shall soon see it 1/8" is the right size. The
first two skewers are out of the dishwasher.


A question for the welders out the Which SS alloys can be welded or hard
(silver) soldered without destroying the stainless property? I see lots of
advice to re-passivate SS items that have been heated to a red heat, to avoid
subsequent corrosion, but for many things I might make re-passivation would
be pretty awkward, and I don't think all SS alloys require this.

For instance, food service furniture is welded and silver brazed, but is far
too large to be dipped into a tank, and brush passivation is too slow.

The answer may be Types 304L and 316L.

I found the following on Wikipedia:

"Low-carbon versions, for example 316L or 304L, are used to avoid corrosion
problem caused by welding. Grade 316LVM is preferred where biocompatibility is
required (such as body implants and piercings). The "L" means that the carbon
content of the alloy is below 0.03%, which reduces the sensitization effect
(precipitation of chromium carbides at grain boundaries) caused by the high
temperatures involved in welding."

Ref: Look near the photo of the girl in the bikini in
http://en.wikipedia.org/wiki/Stainless_steel.

And "9. What does the "L" designation mean?

Answer: The use of the letter L after the grade number, i.e., 304L, means that
the carbon content is restricted to a MAXIMUM of 0.03% (normal levels are 0.08%
max. and in some grades can be as high as 0.15% max.). This lower level of
carbon is usually used where "welding" will be performed. The lower level of
carbon helps to prevent the chromium from being depleted (by forming chrome
carbides at the weld site) and therefore allow it to remain over 10 ‡\0% so it
can form the "passive" oxide layer that gives stainless its corrosion
resistance."

from http://www.ssina.com/faq/index.html#9.

Joe Gwinn

In article ,
" wrote:

On Sep 4, 1:12*pm, Joseph Gwinn wrote:

A question for the welders out the *Which SS alloys can be welded or hard
(silver) soldered without destroying the stainless property? *I see lots of
advice to re-passivate SS items that have been heated to a red heat, to avoid
subsequent corrosion, but for many things I might make re-passivation would
be pretty awkward, and I don't think all SS alloys require this. *


Joe Gwinn

Good question. The higher the chrome and nickel and the lower the
carbon if it is going to be welded. But I do not know about silver
soldering. The problem is that when heated high enough, the carbon in
the stainless combines with the chrome to make chrome carbides. And
that lowers the percentage of chrome so it no longer stainless. I do
not know if the temperature for silver soldering is high enough that
chrome carbides are formed. I also do not know that re-passivating
will help.

I have read that for instance Type 302 can be returned to a state of grace by
annealing after welding, while Type 304 can be used as welded, unless the
corrosion environment is severe. I assume that annealing works by allowing
chromium to diffuse into the chromium-deficient areas.


Found on the internet

If any part of stainless-steel is heated in the range 500 degrees to
800 degrees [C] for any reasonable time there is a risk that the chrome
will form chrome carbides (a compound formed with carbon) with any
carbon present in the steel. This reduces the chrome available to
provide the passive film and leads to preferential corrosion, which
can be severe. This is often referred to as sensitisation. Therefore
it is advisable when welding stainless steel to use low heat input and
restrict the maximum interpass temperature to around 175° [C], although
sensitisation of modern low carbon grades is unlikely unless heated
for prolonged periods. Small quantities of either titanium (321) or
niobium (347) added to stabilise the material will inhibit the
formation of chrome carbides.

Very interesting. Now, we are getting to the bottom of this.

I recall that Type 321 is one of the choices for SS foil for heat treating.
Type 309 being the other choice.


So the temperatures for silver soldering are high enough to cause
problems But the time at high temperatures would be less than for
welding. So I would expect stainless that is silver soldered to be
more corrosion resistant than stainless that has been welded.

Yes. Encouraging, too. I also found the following:
http://www.wisconsinmetaltech.com/guide/type-304.html.

It sounds like I can use Type 304 and 316 for silver soldering, and probably
don't need to use 304L or 316L. So long as one doesn't tarry too long at
temperature.

Which is good, because 304/316 are far more easily bought in small quantities.
Although McMaster carries both L and non-L types, for about the same money.

The food world seems to use 304, but it can be corroded by citrus fruit juice.
One can taste this. When I eat cut fruit with a stainless steel spoon (made of
18/8 if I recall), if the spoon is in contact with the fruit for long, it gets a
very bitter taste. I wonder if 316 is any better.


What's the best way to get the fire scale off the brazed SS assembly?


Joe Gwinn

On Sep 4, 5:43*pm, " wrote:
On Sep 4, 1:12*pm, Joseph Gwinn wrote:

A question for the welders out the *Which SS alloys can be welded or hard
(silver) soldered without destroying the stainless property?

Forgot to answer this part of the question. The higher the chrome and
nickel content the better. 308 is commonly used for welding 304.
But one can use alloys with higher chrome and nickel content. So 309,
310 and 312 all have higher chrome and nickel content.

Dan