A neighbor's friend brought a small welding repair over for me . It's
an I beam that is the backbone of a PTO powered post hole auger . But
that's not what this post is about , this post is about OHMYGAWD I love
my new welder . The flange that carries the yoke that the auger hangs on
had fatigued and split from the web , First order was to pull it back
into position and tack it in place . Then vee one side and run a bead
then flip and grind down to fresh weld and lay in a couple of passes -
all on the lowest power setting . Welding 1/4" thick reinforcing strips
on both sides had it all the way up to half power . I may never need to
use my tombstone welder again ...
--
Snag
"You can lead a dummy to facts
but you can't make him think."

"Snag" wrote in message news:tpfbt0$3ufpe$1@dont-email.me...

A neighbor's friend brought a small welding repair over for me . It's
an I beam that is the backbone of a PTO powered post hole auger . But
that's not what this post is about , this post is about OHMYGAWD I love
my new welder . The flange that carries the yoke that the auger hangs on
had fatigued and split from the web , First order was to pull it back
into position and tack it in place . Then vee one side and run a bead
then flip and grind down to fresh weld and lay in a couple of passes -
all on the lowest power setting . Welding 1/4" thick reinforcing strips
on both sides had it all the way up to half power . I may never need to
use my tombstone welder again ...
Snag

------------------

Flux core?

On 1/8/2023 2:35 PM, Jim Wilkins wrote:
> "Snag"  wrote in message news:tpfbt0$3ufpe$1@dont-email.me...
>  A neighbor's friend brought a small welding repair over for me . It's
> an I beam that is the backbone of a PTO powered post hole auger . But
> that's not what this post is about , this post is about OHMYGAWD I love
> my new welder . The flange that carries the yoke that the auger hangs on
> had fatigued and split from the web , First order was to pull it back
> into position and tack it in place . Then vee one side and run a bead
> then flip and grind down to fresh weld and lay in a couple of passes -
> all on the lowest power setting . Welding 1/4" thick reinforcing strips
> on both sides had it all the way up to half power . I may never need to
> use my tombstone welder again ...
> Snag
>
> ------------------
>
> Flux core?
>

I've been debating selling mine. On the rare occasion when I really
might need to burn some 7018 for some thicker plate I have the AHP ACDC
Pulse TIG/Stick. I like running DC stick so much better than using the
AC cracker box.

--
Bob La Londe
CNC Molds N Stuff

--
This email has been checked for viruses by AVG antivirus software.
www.avg.com

On Sun, 8 Jan 2023 15:46:47 -0700, Bob La Londe <none@none.com99>
wrote:

>On 1/8/2023 2:35 PM, Jim Wilkins wrote:
>> "Snag"  wrote in message news:tpfbt0$3ufpe$1@dont-email.me...
>>  A neighbor's friend brought a small welding repair over for me . It's
>> an I beam that is the backbone of a PTO powered post hole auger . But
>> that's not what this post is about , this post is about OHMYGAWD I love
>> my new welder . The flange that carries the yoke that the auger hangs on
>> had fatigued and split from the web , First order was to pull it back
>> into position and tack it in place . Then vee one side and run a bead
>> then flip and grind down to fresh weld and lay in a couple of passes -
>> all on the lowest power setting . Welding 1/4" thick reinforcing strips
>> on both sides had it all the way up to half power . I may never need to
>> use my tombstone welder again ...
>> Snag
>>
>> ------------------
>>
>> Flux core?
>>
>
>I've been debating selling mine. On the rare occasion when I really
>might need to burn some 7018 for some thicker plate I have the AHP ACDC
>Pulse TIG/Stick. I like running DC stick so much better than using the
>AC cracker box.
>
>--
>Bob La Londe
>CNC Molds N Stuff
I've got a lincoln AC/DC "tombstone" and it's plenty heavy enough for
anything I do - sure like the DC capability. Don't have occaision to
use it much as it's a bit TOO big for some od the stuff I've been into
lately where I have a buddy TIG for me

On 1/8/2023 3:35 PM, Jim Wilkins wrote:
> "Snag"  wrote in message news:tpfbt0$3ufpe$1@dont-email.me...
>  A neighbor's friend brought a small welding repair over for me . It's
> an I beam that is the backbone of a PTO powered post hole auger . But
> that's not what this post is about , this post is about OHMYGAWD I love
> my new welder . The flange that carries the yoke that the auger hangs on
> had fatigued and split from the web , First order was to pull it back
> into position and tack it in place . Then vee one side and run a bead
> then flip and grind down to fresh weld and lay in a couple of passes -
> all on the lowest power setting . Welding 1/4" thick reinforcing strips
> on both sides had it all the way up to half power . I may never need to
> use my tombstone welder again ...
> Snag
>
> ------------------
>
> Flux core?
>

Yup , the roll this welder came with when it was brand new . I never
realized how handicapped that WeldPak 100 was ! I was going to set it up
for .030 solid wire for this repair , but there was enough of a breeze
today that flux core was a better choice .
--
Snag
"You can lead a dummy to facts
but you can't make him think."

On 1/8/2023 4:46 PM, Bob La Londe wrote:
> On 1/8/2023 2:35 PM, Jim Wilkins wrote:
>> "Snag"  wrote in message news:tpfbt0$3ufpe$1@dont-email.me...
>>   A neighbor's friend brought a small welding repair over for me .
>> It's an I beam that is the backbone of a PTO powered post hole auger .
>> But that's not what this post is about , this post is about OHMYGAWD I
>> love my new welder . The flange that carries the yoke that the auger
>> hangs on had fatigued and split from the web , First order was to pull
>> it back into position and tack it in place . Then vee one side and run
>> a bead then flip and grind down to fresh weld and lay in a couple of
>> passes - all on the lowest power setting . Welding 1/4" thick
>> reinforcing strips on both sides had it all the way up to half power .
>> I may never need to use my tombstone welder again ...
>> Snag
>>
>> ------------------
>>
>> Flux core?
>>
>
> I've been debating selling mine.  On the rare occasion when I really
> might need to burn some 7018 for some thicker plate I have the AHP ACDC
> Pulse TIG/Stick.  I like running DC stick so much better than using the
> AC cracker box.
>

Mine's probably worth more as scrap ... I've read that these IGBT
welding machines have a bit of a different current profile , had mine
for several years now and I've never even plugged the stinget cable into
the machine . My stick welding sucks and I avoid it when I can .
--
Snag
"You can lead a dummy to facts
but you can't make him think."

"Snag" wrote in message news:tpflmq$3vdrl$1@dont-email.me...

Mine's probably worth more as scrap ... I've read that these IGBT
welding machines have a bit of a different current profile , had mine
for several years now and I've never even plugged the stinget cable into
the machine . My stick welding sucks and I avoid it when I can .
Snag

----------------------

I was terrible at stick welding until I took a night school class in it and
was shown the proper preparation and technique, and introduced to 7018 DC. I
spent all 6 sessions practicing making and breaking welds until finally I
could fold one double without a crack. Then I built the front end loader and
sawmill.

It was just as helpful and more economical of steel to run many parallel
beads across one piece of randomly shaped steel scrap instead of joining two
straight-edged pieces.

On 1/9/2023 10:50 AM, Jim Wilkins wrote:
> "Snag"  wrote in message news:tpflmq$3vdrl$1@dont-email.me...
>
> Mine's probably worth more as scrap ... I've read that these IGBT
> welding machines have a bit of a different current profile , had mine
> for several years now and I've never even plugged the stinget cable into
> the machine . My stick welding sucks and I avoid it when I can .
> Snag
>
> ----------------------
>
> I was terrible at stick welding until I took a night school class in it
> and was shown the proper preparation and technique, and introduced to
> 7018 DC. I spent all 6 sessions practicing making and breaking welds
> until finally I could fold one double without a crack. Then I built the
> front end loader and sawmill.
>
> It was just as helpful and more economical of steel to run many parallel
> beads across one piece of randomly shaped steel scrap instead of joining
> two straight-edged pieces.
>

I did that with the TIG . I should do a sheet or two with the stick ,
I may be able to do better now . I've been studying puddles ... and it
helped my MIG welding , may be it could help with stick too .
--
Snag
"You can lead a dummy to facts
but you can't make him think."

On 1/9/2023 3:08 PM, Snag wrote:
> On 1/9/2023 10:50 AM, Jim Wilkins wrote:
>> "Snag"  wrote in message news:tpflmq$3vdrl$1@dont-email.me...
>>
>> Mine's probably worth more as scrap ... I've read that these IGBT
>> welding machines have a bit of a different current profile , had mine
>> for several years now and I've never even plugged the stinget cable into
>> the machine . My stick welding sucks and I avoid it when I can .
>> Snag
>>
>> ----------------------
>>
>> I was terrible at stick welding until I took a night school class in
>> it and was shown the proper preparation and technique, and introduced
>> to 7018 DC. I spent all 6 sessions practicing making and breaking
>> welds until finally I could fold one double without a crack. Then I
>> built the front end loader and sawmill.
>>
>> It was just as helpful and more economical of steel to run many
>> parallel beads across one piece of randomly shaped steel scrap instead
>> of joining two straight-edged pieces.
>>
>
>   I did that with the TIG . I should do a sheet or two with the stick ,
> I may be able to do better now . I've been studying puddles ... and it
> helped my MIG welding , may be it could help with stick too .

The stick part is easy. Its the welding part that's hard after you
establish the stick.

--
Bob La Londe
CNC Molds N Stuff

--
This email has been checked for viruses by AVG antivirus software.
www.avg.com

"Jim Wilkins" <muratlanne@gmail.com> writes:

> "Snag" wrote in message news:tpflmq$3vdrl$1@dont-email.me...
>
>> Mine's ...
>
> ----------------------
>
> I was terrible at stick welding until I took a night school class in
> it and was shown the proper preparation and technique, and introduced
> to 7018 DC. I spent all 6 sessions practicing making and breaking
> welds until finally I could fold one double without a crack. Then I
> built the front end loader and sawmill.
>
> It was just as helpful and more economical of steel to run many
> parallel beads across one piece of randomly shaped steel scrap instead
> of joining two straight-edged pieces.

That's the almost universal story of learning welding - starting off
as a basic but competent welder-the-person, isn't it?

Doing "pad-welds" is a great start. When you can lay a neat pad
(which you might do "in real life" - build-up a worn section of a
machine), you probably control angles (tilt and slope), run-rate,
where exactly you are pointing the rod - so "you know where you are
going with it" you have the basics of depositing metal.
Well to be commended.

Then making-and-breaking welds - that learning cycle.
Makes you "engineering-minded". You are visualising a weld which will
do the job and doing it.
I worked in a college in a terribly deprived part of London and also
did welding training there, and I can tell you - the welding school is
always an oasis. If you went in and saw any person and asked what
they are working at, they'd show you "the next weld" they are trying
to master, how they have improved, what they think will get them there
and what their hope is "I'm hoping to have 'got it' by midday meal
break / by afternoon tea-time / etc. All on their own mission.
(unlike a classroom where you are trying to get a cohort along one
shared learning path).
The self-motivation is astonishing in a welding school, compared to
the miasma of hopelessness which can be most of the rest of the place.

"Don't make welds without breaking welding" is the root.

Here in the UK in production environments if that had that principle
in mind most of the problems would not be there. As I have seen.

In education to fit "frameworks" (sic.) they have split up years into
"appearance" and then "doing breaks and macros".
Never do that - the advance is fine-scale evolution make-and-break
(and macro).

So - big yes, yes, yes, concurring that is exactly the way and so it
is that it was so for me.

Regards,
Rich Smith

Welding is complexly dependent on several physical Laws of the
Universe, unless a situation is so familiar and you know how good and
bad welds run, you really should be doing test-welds.

Then what you mention next - the problems I have seen in the UK if
they did this most basic thing they'd get out of those problems.

"Richard Smith" wrote in message news:ly7cxt7ceq.fsf@void.com...
....
In education to fit "frameworks" (sic.) they have split up years into
"appearance" and then "doing breaks and macros".
Never do that - the advance is fine-scale evolution make-and-break
(and macro).

So - big yes, yes, yes, concurring that is exactly the way and so it
is that it was so for me.

Regards,
Rich Smith

-------------------

I didn't realize how hide-bound the educational establishment was until I
started taking night classes with teachers who worked for a living. Instead
of worshipping the formal structure of, say, Calculus they taught it as a
useful tool, and finally I could understand it. In the college textbook the
Limit process that underlies differentiation and integration took up one
paragraph. The night class spent two weeks on the Limit origins of the
memorized formulas and then they made sense. A useful trick I learned was
memorizing reciprocals, which enables mental division and simplifies setting
up a lathe to cut screw threads. Afterwards I could solve questions of
frequency, capacitance and inductance in my head before the engineer could
find his calculator.

https://ecologyisnotadirtyword.com/2017/08/27/applied-vs-pure-its-all-ecology-at-the-end-of-the-day/
" ‘Pure’ scientists were often more disparaging of applied science than the
other way around. This kind of scholarly rivalry has been around since the
ancient in-fighting between classical philosophers. John Dewey (among
others) saw it as simple class snobbery:"

I see it as denying the value of what they aren't good at. An article I read
about Los Alamos mentioned a camping trip which revealed that many of the
world's top theoretical physicists couldn't light a fire. The author was the
only physicist who could weld, and thus quickly fixed many problems the
others would have sought a consultant for -- a considerable delay on a
highly classified project.

The local night schools have been lucky to find excellent nuclear and bridge
certified welders who could also teach. They have more trouble finding
qualified instructors for the other subjects they would like to offer such
as small engine repair, so much that they asked if I was interested. There
are too many gaps in my self-education for that. I took the auto repair
course to learn what's new and maybe lose any bad habits I'd acquired.
jsw

"Richard Smith" wrote in message news:ly7cxt7ceq.fsf@void.com...

Doing "pad-welds" is a great start. When you can lay a neat pad
(which you might do "in real life" - build-up a worn section of a
machine), you probably control angles (tilt and slope), run-rate,
where exactly you are pointing the rod - so "you know where you are
going with it" you have the basics of depositing metal.
Well to be commended.

--------------------

On my own initiative I practiced filling in coin-sized holes with MIG and
piling up aluminum stalagmites with TIG, to refine my puddle control. I
think they were good practice though I haven't seen them recommended.

"Jim Wilkins" <muratlanne@gmail.com> writes:

> "Richard Smith" wrote in message news:ly7cxt7ceq.fsf@void.com...
> ...
> ...

> -------------------
>
> I didn't realize how hide-bound the educational establishment was
> until I started taking night classes with teachers who worked for a
> living. Instead of worshipping the formal structure of, say, Calculus
> they taught it as a useful tool, and finally I could understand it.

Yes I met this teaching vocational students. Showing them the theory
and maths is actually good and useful.

I can barely understand a word of mathematics books for techniques I
have "re-invented" and used given a need.

> ...

> https://ecologyisnotadirtyword.com/2017/08/27/applied-vs-pure-its-all-ecology-at-the-end-of-the-day/
> " ‘Pure’ scientists were often more disparaging of applied science
> than the other way around. ...

When doing my welding engineering masters the two of us who were
welders - the poor Head of Department would rather have endured an
untreated case of an embarrassing socially transmitted condition than
have to talk with one of us.

Poor fellow!

The thing is we - the two of us welders - often knew that things don't
work the way he was trying to help us see the way to proceed.
Also some welding conditions are so exact that you have to know they
are there and recognise your way to a very exact condition a matrix of
test conditions could never find (the combinations are unimaginably
immense). There were all sorts of things where we knew "God's design"
and were therefore respectful of it.
eg. response
"If you as much of think of iron and titanium in the same thought they
form a brittle intermetallic phase"
Obviously that is superlative, but the direction of the conversation
can be inferred :-)

But yes the poor fellow thought his esteemed theoretical science was
superior to our "applied science".
Oh gawd - the poor fellow threatened to walk out of a meeting after I
explained a strategy he suggested would not work - until he looked
around and realised we were in his own office - he'd threatened to
walk out of his own office ...

We did feel a bit sorry for him...

Rich S

"Richard Smith" wrote in message news:ly7cxt7ceq.fsf@void.com...

"Don't make welds without breaking welding" is the root.

Here in the UK in production environments if that had that principle
in mind most of the problems would not be there. As I have seen.

-----------------------

I've been testing things to destruction since high school, on a Tinius Olsen
tensile strength tester at an after-school factory job. I destroyed a
prototype GM fuel injection computer by subjecting it to the overvoltage
abuse it was supposed to withstand, on a machine I built to their specs.

https://en.wikipedia.org/wiki/Load_dump

I don't know if the 40V spec applies to welding, I disconnect the battery
just in case. The energy in a load dump is whatever was stored in the
alternator rotor's inductance, not continuous like a welder, although it can
repeat, so my machine had time delay relays to let them set the pulse
repetition rate. They specified a maximum time that included their
undisclosed intended setting.

At the time, the mid 70's, electronics was new to the automotive industry
which previously had nothing more complex than a radio they bought. They
hired a lot of bright new electrical engineers who had to painfully learn
the decidedly non-theoretical conditions of road vehicles and typical
American lack of maintenance. I did have the slight advantage of coming from
military electronics which have to take anything Nature throws at them,
though at a commercially unacceptable cost and weight penalty.

"Richard Smith" wrote in message news:lyzgaosyk9.fsf@void.com...
....
But yes the poor fellow thought his esteemed theoretical science was
superior to our "applied science".
Oh gawd - the poor fellow threatened to walk out of a meeting after I
explained a strategy he suggested would not work - until he looked
around and realised we were in his own office - he'd threatened to
walk out of his own office ...

We did feel a bit sorry for him...

Rich S
-----------------------------
Chemistry was different, the theory had evolved to explain unexpected
experimental results. Newton had been able to puzzle out the underlying
principles of Physics, Optics and Calculus but he utterly failed with
Chemistry. The last critical step came in 1932 with Chadwick's discovery of
the Neutron, which finally explained why many elements didn't have the
simple integer atomic weight relationships the prevailing theory predicted.

I didn't encounter pure theoreticians outside the classroom until later and
by then I knew enough to deal with them. One Ph.D didn't know that resistors
come with tolerance bands, he expected 8 digit precision until shown the
commercial reality, and he didn't know how to handle measurement uncertainty
as chemists have learned to. His final product had a 40% tolerance.

https://learn.parallax.com/support/reference/resistor-color-codes
Tolerances down to 0.01% are available if you need and can afford them. When
I was building industrial test equipment in the 1980's they were $5 each,
standard ones were $0.10 or less. Any that we drew from stock for lab use
became "tainted" and couldn't be returned, so I have a decent supply of
lightly used ones to calibrate my meters since I was building and
programming the test and calibration fixtures.

At Mitre the pure theoreticians apparently knew better than to try to design
actual hardware, so the Ph.Ds I worked for had practical experience. I still
could think of simplifying shortcuts they hadn't, to the extent that they
handed me data sheets for the critical components and left me to figure out
how to use them.

"Richard Smith" wrote in message news:lyzgaosyk9.fsf@void.com...

There were all sorts of things where we knew "God's design"
and were therefore respectful of it.
eg. response
"If you as much of think of iron and titanium in the same thought they
form a brittle intermetallic phase"
Obviously that is superlative, but the direction of the conversation
can be inferred :-)

-----------------------

Huh?

https://science.jrank.org/pages/6852/Titanium-Uses.html

"By far the most important use of titanium is in making alloys. It is the
element most commonly added to steel because it increases the strength and
resistance to corrosion of steel."

On 11/01/2023 23:05, Jim Wilkins wrote:
> "Richard Smith"  wrote in message news:lyzgaosyk9.fsf@void.com...
>
> There were all sorts of things where we knew "God's design"
> and were therefore respectful of it.
> eg. response
> "If you as much of think of iron and titanium in the same thought they
> form a brittle intermetallic phase"
> Obviously that is superlative, but the direction of the conversation
> can be inferred :-)
>
> -----------------------
>
> Huh?
>
> https://science.jrank.org/pages/6852/Titanium-Uses.html
>
> "By far the most important use of titanium is in making alloys. It is
> the element most commonly added to steel because it increases the
> strength and resistance to corrosion of steel."
>
It may be like the effect of manganese in steel and depends on the
percentage, see https://en.wikipedia.org/wiki/Mangalloy also known as
Hadfield steel. It mentions as I remembered that around 5% - 6%
manganese addition it becomes so brittle it can be pulverised with a
hammer beyond that things change and it becomes extremely durable and
abrasion resistant. I may have some as I have an ore crusher knuckle
somewhere.

"David Billington" wrote in message news:tpngk2$11tvm$1@dont-email.me...

On 11/01/2023 23:05, Jim Wilkins wrote:
> "Richard Smith" wrote in message news:lyzgaosyk9.fsf@void.com...
>
> There were all sorts of things where we knew "God's design"
> and were therefore respectful of it.
> eg. response
> "If you as much of think of iron and titanium in the same thought they
> form a brittle intermetallic phase"
> Obviously that is superlative, but the direction of the conversation
> can be inferred :-)
>
> -----------------------
>
> Huh?
>
> https://science.jrank.org/pages/6852/Titanium-Uses.html
>
> "By far the most important use of titanium is in making alloys. It is
> the element most commonly added to steel because it increases the
> strength and resistance to corrosion of steel."
>
It may be like the effect of manganese in steel and depends on the
percentage, see https://en.wikipedia.org/wiki/Mangalloy also known as
Hadfield steel. It mentions as I remembered that around 5% - 6%
manganese addition it becomes so brittle it can be pulverised with a
hammer beyond that things change and it becomes extremely durable and
abrasion resistant. I may have some as I have an ore crusher knuckle
somewhere.

-----------------------------

Tin bronze is like that, at a 2:1 mix it's quite brittle.
https://en.wikipedia.org/wiki/Speculum_metal

"Jim Wilkins" <muratlanne@gmail.com> writes:

> "Richard Smith" wrote in message news:lyzgaosyk9.fsf@void.com...
>
> There were all sorts of things where we knew "God's design"
> and were therefore respectful of it.
> eg. response
> "If you as much of think of iron and titanium in the same thought they
> form a brittle intermetallic phase"
> Obviously that is superlative, but the direction of the conversation
> can be inferred :-)
>
> -----------------------
>
> Huh?
>
> https://science.jrank.org/pages/6852/Titanium-Uses.html
>
> "By far the most important use of titanium is in making alloys. It is
> the element most commonly added to steel because it increases the
> strength and resistance to corrosion of steel."

My impression is you shouldn't place too much credence on the "jrank"
link.

The brittleness is any attempt to bring together a piece of titanium
and a piece of iron/steel.

Alloying - broadly (forgive me experienced steel metallurgists)
Titanium as an alloying addition is one of the very reactive alloying
elements usually used in small quantities, like Aluminium, Calcium,
Niobium, etc.
With an already "clean" melt, Titanium is a ferocious "getter" for
non-metallics in the melt. Titanium reactant precipitates feature in
grain-refining. It might feature in a super-refined melt going to a
High-Strength Low-Alloy steel - eg. a Thermo-Mechanically
Controlled-Processed steel (see Dillinger Huette and the few others in
the world (?) who can do this).
I guess that throw Titanium in a "rough" melt and it would be entirely
consumed and lost "getting" oxygen which could be much more cheaply
removed with Aluminium.

Get someone who works with this stuff to comment if it's important to
you.

In Sheffield there was an alloy with a small Titanium addition and it
was a few Rockwell hardnesses above what it should have been. If they
could have understood where it came from and what its characteristics
were it would have been a very cheap way to get a stronger harder
steel, if all else were well.
I had a go at it - it would grain-grow if left a long time at a high
temperature, so that eliminated some hypotheses at what was going on.
Etc.

I am not completely without knowledge, but do get experienced advice
if it matters.

However, as I say, this link
https://science.jrank.org/pages/6852/Titanium-Uses.html
tries to simplify more than gives usable impressions.

Regards,

On Wednesday, January 11, 2023 at 1:42:18 PM UTC-5, Richard Smith wrote:

> I can barely understand a word of mathematics books for techniques I
> have "re-invented" and used given a need.

Having been looking at your website and in particular at your thesis
recently... yeah, I can tell. I mean, that "sixth-jumping" technique of
numerical computation is brilliant. One could probably derive it from
the partial differential equation for diffusion (in a derivation that would
involve making approximations at various points), and that would be
theorists' way of doing it. But you just pulled it out of your hat, as
if it were obvious, which in a way it is. It's not the most efficient way
to do the computation, but it will do, and is simple and direct. (If you
ever have that task again, look for a heat equation solver and pretend
hydrogen content is "heat", the heat equation is the same as that
for diffusion.) In any case, a theorist would have made it sound more
profound, but wouldn't have done it any better -- at least as regards the
core algorithm.

On the other hand, your treatment of boundaries between regions with
different diffusion coefficients really could have used a theorist's input,
because the first thing to decide from a theoretical perspective is what
the boundary condition should be. And the usual boundary condition for
diffusion is that the concentrations on each side of the boundary are
equal -- whereas you looked at your algorithm, whose process resulted
in (at the boundary) a sharp jump in concentrations, and took that as
given. It's not; you have a clever hack for changing the diffusion
coefficient that works fine on either side of the boundary, but that hack
should not be taken as an inevitable statement of what happens at the
boundary. There are other possible hacks, such as changing the cell
size on the slower-diffusing side to be smaller, which would give no
jump.

Sometimes there can indeed be a sharp jump; for instance if one side
has a greater chemical affinity to the thing that is diffusing, then
there's an energy level difference across the boundary, and since it's
harder to go uphill than downhill the result is a jump in concentrations.
But in this case that seems unlikely since you still basically have steel
on both sides of the boundary: a hydrogen atom that wanders across
the boundary won't find much change in conditions. (On a basic physics
level, the diffusion can't be purely a process of jumping from one site that
traps hydrogen to another; there's got to be some wandering-around
between such sites, and it's the wandering-around that determines what
site it lands in.) A sharp jump in concentration can't absolutely be
ruled out, but shouldn't be assumed, either.

This doesn't affect the main results of your thesis, of course. I was reading
it because although I'd heard of hydrogen embrittlement, the fact that
hydrogen actually could be observed bubbling out of a freshly welded
surface (under the right conditions) was new to me and intriguing.

Anyway, learning the theory of partial differential equations well
enough to use it takes a lot of time and effort, and no one can be
blamed for not doing so (unless of course that's what they're
being paid for).

> When doing my welding engineering masters the two of us who were
> welders - the poor Head of Department would rather have endured an
> untreated case of an embarrassing socially transmitted condition than
> have to talk with one of us.

"Their minds bred in and in, and were accordingly cursed with barrenness
and degeneracy. No extraneous beauty or vigor was engrafted on the
decaying stock. By an exclusive attention to one class of phenomena,
by an exclusive taste for one species of excellence, the human intellect
was stunted."

I think that quote sums it up.

---
Norman Yarvin
yarvin@yarchive.net

Norman Yarvin <norman.yarvin@gmail.com> writes:

> On Wednesday, January 11, 2023 at 1:42:18 PM UTC-5, Richard Smith wrote:
>
>> I can barely understand a word of mathematics books for techniques I
>> have "re-invented" and used given a need.
>
> Having been looking at your website and in particular at your thesis
> recently... yeah, I can tell. I mean, that "sixth-jumping" technique of
> numerical computation is brilliant. One could probably derive it from
> the partial differential equation for diffusion (in a derivation that would
> involve making approximations at various points), and that would be
> theorists' way of doing it. But you just pulled it out of your hat, as
> if it were obvious, which in a way it is. It's not the most efficient way
> to do the computation, but it will do, and is simple and direct. (If you
> ever have that task again, look for a heat equation solver and pretend
> hydrogen content is "heat", the heat equation is the same as that
> for diffusion.) In any case, a theorist would have made it sound more
> profound, but wouldn't have done it any better -- at least as regards the
> core algorithm.
>
> On the other hand, your treatment of boundaries between regions with
> different diffusion coefficients really could have used a theorist's input,
> because the first thing to decide from a theoretical perspective is what
> the boundary condition should be. And the usual boundary condition for
> diffusion is that the concentrations on each side of the boundary are
> equal -- whereas you looked at your algorithm, whose process resulted
> in (at the boundary) a sharp jump in concentrations, and took that as
> given. It's not; you have a clever hack for changing the diffusion
> coefficient that works fine on either side of the boundary, but that hack
> should not be taken as an inevitable statement of what happens at the
> boundary. There are other possible hacks, such as changing the cell
> size on the slower-diffusing side to be smaller, which would give no
> jump.
>
> Sometimes there can indeed be a sharp jump; for instance if one side
> has a greater chemical affinity to the thing that is diffusing, then
> there's an energy level difference across the boundary, and since it's
> harder to go uphill than downhill the result is a jump in concentrations.
> But in this case that seems unlikely since you still basically have steel
> on both sides of the boundary: a hydrogen atom that wanders across
> the boundary won't find much change in conditions. (On a basic physics
> level, the diffusion can't be purely a process of jumping from one site that
> traps hydrogen to another; there's got to be some wandering-around
> between such sites, and it's the wandering-around that determines what
> site it lands in.) A sharp jump in concentration can't absolutely be
> ruled out, but shouldn't be assumed, either.
>
> This doesn't affect the main results of your thesis, of course. I was reading
> it because although I'd heard of hydrogen embrittlement, the fact that
> hydrogen actually could be observed bubbling out of a freshly welded
> surface (under the right conditions) was new to me and intriguing.
>
> Anyway, learning the theory of partial differential equations well
> enough to use it takes a lot of time and effort, and no one can be
> blamed for not doing so (unless of course that's what they're
> being paid for).
>
>> When doing my welding engineering masters the two of us who were
>> welders - the poor Head of Department would rather have endured an
>> untreated case of an embarrassing socially transmitted condition than
>> have to talk with one of us.
>
> "Their minds bred in and in, and were accordingly cursed with barrenness
> and degeneracy. No extraneous beauty or vigor was engrafted on the
> decaying stock. By an exclusive attention to one class of phenomena,
> by an exclusive taste for one species of excellence, the human intellect
> was stunted."
>
> I think that quote sums it up.
>
> ---
> Norman Yarvin
> yarvin@yarchive.net

The "sixth-jumping" technique came to me having read Adolf Fick's
original 1855 (?) scientific paper. It is wise. He knows most
"assumptions" on the way to formulating his "Fick's Laws" are not
going to be so in most realities,

(I believe you can see "Fickian Diffusion" if you use a radioactive
tracer isotope on one side of a boundary (same element; difference in
the nucleus not affecting chemical properties), and see it mix in time
and have a way to detect concentration of "origin-1" to "origin-2"
atoms by radioactivity) - other than that - no chance...)

I saw that if you have "an automatic computer" ("a computer") you
don't need to formulate differential equations.

A person of Middle-Eastern origin showed me the computational method
for solving mathematical integration ("calculus") approximately but
achievably. But having seen that, my "sixth-jumping model" came to
me. My sixth-jumping model used as a general solution does have
"convergence" with increasing discretisation, by the way, stating the
obvious.

The algorithm is / was very efficient. The Computer Science people
were very glad of seeing the real performance of computers revealed,
by reason of knowing exactly how many operations my algorithm had to
do to go each step of the solution.

By the way - when I did my Doctoral research back up to the late
1990's, it really wasn't then possible to solve in 3 dimensions for
mathematical expressions for conductive heat flow and diffusion.
The computer memory requirement; the computing time.
Now; yes - "even I" solve for stresses and strains in 3 dimensions
with Finite Element Analysis programs.
But then, being realistic...
I had 80MB of memory, which was five times a good-spec computer then,
and people used to sit there drooling watching the computer go through
its boot-up routine and check the memory. But I had to fit a
3-dimensional computational model into that. I did not need or use
"swap-space" on a hard-disk - the entire solution fitted into the
computer memory.

That is a digression from hydrogen in metals.

*** My solution did the right thing. ***
That must be surely correct because it explains so much.
You talk of "boundaries" and "boundary conditions". How could anyone
have prior knowledge of what to set this at???
I found scientific "papers" where solutions were presented which were
mathematically correct but physically incorrect.
My solution is a model which done sytematically gives a quantitative
result. It "shows the way" because it is a model.

You talk about "hacks" - but this solution, which is the
implementation of a model, is "pure" - you know what it represents
physically.

I don't think I am contributing anything, because your comment is very
insightful and I get the impression you are a genuine scientist.

I would commend anyone interested to go back and re-read what you have
written after reading these comments of mine, because of the quality
of your understanding.

PS - I used the "sixth-jumping" solution for two years before I ever
explained to anyone how it worked. It took me something like 20
minutes to find an explanation which worked, to a person who was an
expert in diffusion and had made useful discoveries. He finally "got
it" and asked "So if Adolf Fick had had an automatic computer, he
would have solved for diffusion this way?", to which I replied
something like "Almost certainly".

Norman - the reality at the time, in the early 1990's, was that these
German and Japanese Thermo-Mechanically Controlled-Processed plate
High-Strength Low-Alloy steels were so superior, leaving "us" having
to buy these steels and put them through our pipe-mills while plate
capacity here stood idle.
One advantage was their weldability. That was what I sought to
address. Previous weld cracking susceptibility tests we had - you
could set every variable to the maximum and the TMCP steels would not
crack ever.

There were other advantages. Tough at arctic temperatures. High
strength. Highly resistant to "sour" crude oils for pipelines. Etc.

I "got" weldability and sour oil resistance.

I set out to understand the weldability. That explanation also
explained the resistance to "SOHIC" - sour oil resistance.

Models lead the way, and what mine showed appears to explain
everything.
I would have needed more tests to prove whether the apparent
explanation was the actual explanation - but I had had a bruising
journey through my PhD, and the thought of more time in academia was
so horrible I didn't even have it.

Regarding this work and how you seem to find it remarkable - in "bang
for buck"? - I found others.
One is "fatigue-resistant welds"
http://weldsmith.co.uk/tech/fatgres/210209_hiperfstrlstl_intro/210209_hiperfstrlstl_intro.html
"Invitation to take interest in high-performance steel structures for cyclic-loading ("fatiguing") applications"
Again I played an instinct - I had no plan but was curious about how
"low specification" welds would perform in fatigue and did an "extra
sample". It hadn't even got any cracks started at nearly six times
the cycles it should have broken.

Then there's been well-chosen welding techniques.

I have helped people who know me with analyses which solved major
"challenges" but they are confidential.

This was the best work I got
http://www.weldsmith.co.uk/career/writing/3bb_2015/1703_3BBp_RDS_memoir.html
"Memoir - the 3rd Bosphorus Bridge project, Turkey, 2015"

BTW I did a memoir of the Doctoral research I did
http://www.weldsmith.co.uk/career/writing/phd/1701_hmov_weldzone_platesteels_story.html
"Memoir of my Doctoral research endeavour"

Norman - no-one previously knew there was a more than 3-fold
difference in the diffusivity ("movement rate") of hydrogen in "plate
steels" - thicker C-Mn steels used for general construction,
pipelines, ships, etc.
I found that out experimentally early on.
That was a surprise. It had my thoughts going on a path which lead to
"the sixth-jumping solution".
In all fairness - those initiating and putting together the project
had that intuition that movement could surely be the only aspect
concealing the explanation seeing as so much is / was known about
other things. The steel samples they had assembled for me was an
embodiment of that intuition of theirs.
But in all fairness to me - I found the test(s) which revealed the
hydrogen-movement behaviour, when everyone else thought it
all-but-impossible.
My experiments had about the same qualities as my computational model
/ solution, I suggest...

My "Wedge Weld Hydrogen Penetration" test - that only works because
there are things going on we do not understand. But the pattern of
results is so exact - movement-distance is strictly proportional to
square-root of time always as ever seen. So there was confidence to
use this "unexpected bounty".
But the thing is, I did a "scattergun" approach early on, with
"dead-certs" not working at all and "almost no hope'ers" astonishing
with being workhorses - the WWHP test being one.

You are clearly a scientist - there were about four previous
scientific papers on hydrogen mmovement in welds - none with any
analysis of what physical phenomena are giving the results.
You will be knowing - that is double-unusual.
* tiny number of previous investigations reported (and that being more
because cooperation in welding science never ceased during the Cold
War)(you'd be expecting thousands minimum given the economic,
commercial and military relevance).
* a scientific paper published with no mechanistic model trying to
explain the results is rare

So that investigation could have been subtitled "To boldly go where
no-one considered it a particularly good idea to go before".

On Thursday, January 19, 2023 at 11:12:03 PM UTC-5, Richard Smith wrote:
> The "sixth-jumping" technique came to me having read Adolf Fick's
> original 1855 (?) scientific paper. It is wise. He knows most
> "assumptions" on the way to formulating his "Fick's Laws" are not
> going to be so in most realities,
>
> (I believe you can see "Fickian Diffusion" if you use a radioactive
> tracer isotope on one side of a boundary (same element; difference in
> the nucleus not affecting chemical properties), and see it mix in time
> and have a way to detect concentration of "origin-1" to "origin-2"
> atoms by radioactivity) - other than that - no chance...)

To me it's just "diffusion": with that sort of basic process -- particles
wandering around randomly -- it's hard for there to be any other
governing law.

> I saw that if you have "an automatic computer" ("a computer") you
> don't need to formulate differential equations.

Well, the differential equation is simply the difference equation (what
you used) taken to the limit of infinite resolution: not a big step in and
of itself, but it opens the door to taking advantage of some
powerful mathematical techniques (as well as of course the risk
of getting lost in math and never finishing your project).

> By the way - when I did my Doctoral research back up to the late
> 1990's, it really wasn't then possible to solve in 3 dimensions for
> mathematical expressions for conductive heat flow and diffusion.
> The computer memory requirement; the computing time.

Ah, but that presumes you're storing a number for every point in
a 3-dimensional grid and doing a calculation at each point for
every timestep. There are more sophisticated ways: for instance
one way to solve the heat equation is to take the FFT of your starting
state (in all three dimensions, one at a time), after which you can get
the solution at any subsequent time by just multiplying each FFT
coefficient by an easily-calculated value (an exponential decay
proportional to spatial frequency) and doing the inverse FFT
transforms. (No time-stepping: just go directly to the desired time.)

Now, that only applies to a 3D rectangular block, and your shape
was a bit more complicated than that, so you couldn't have done
exactly that; but it's an illustration of the sorts of techniques that are
out there (and that these days you could access by just using a good
heat equation solver and pretending hydrogen concentration was heat).

> You talk of "boundaries" and "boundary conditions". How could anyone
> have prior knowledge of what to set this at???
> I found scientific "papers" where solutions were presented which were
> mathematically correct but physically incorrect.

You answered that one yourself: demand physical correctness. (And
beware of math tricks; admit no bad assumptions.)

> You talk about "hacks" - but this solution, which is the
> implementation of a model, is "pure" - you know what it represents
> physically.

Hack is not a dirty word here; it just means not taking as much care as
would be taken in a really thorough solution. Like, it may seem a waste
of time to take your difference equation, take the limit to make it a
differential equation, only to convert it back to a difference
equation to actually solve it. And for your purposes of your thesis it
probably would have been a waste of time. But the differential equation
is closer to the actual physics, and in the process of converting it back
to a difference equation you learn what sort of errors you'll be making
and have opportunities to improve them.

Hacks that work are great; it's just that not all of them work. You mostly
validated your solver, by checking against an analytical (textbook)
solution, so that part worked, but I don't believe you validated the
aspect of the solver that gave you sharp jumps across boundaries
between different diffusion coefficients.

On Friday, January 20, 2023 at 3:09:54 AM UTC-5, Richard Smith wrote:
> Norman - the reality at the time, in the early 1990's, was that these
> German and Japanese Thermo-Mechanically Controlled-Processed plate
> High-Strength Low-Alloy steels were so superior, leaving "us" having
> to buy these steels and put them through our pipe-mills while plate
> capacity here stood idle.

Has that improved? (Or has it gotten worse, with no longer even a
British attempt to compete?)