"Jim Wilkins" <
[email protected]> writes:
"Richard Smith" wrote in message news:[email protected]...
What I'd be looking for is the weld bursting after some standing time
- one aspect to "cold-cracking" is that it can be delayed. The reason is well-known - one hydrogen concentration mechanism is to flow uphill
against an apparent concentration gradient to a region in a high state
of triaxial stress. Which for a fillet weld in tension you'd expect
to be near the fillet toe...
Rich Smith
----------------------------------
More spaces for it in a deformed lattice?
That is a model you could have in your mind.
When you are ready, look further.
I am no "Einstein", but I think you have to have a vision of the
metallic bond and energy levels.
I came up with an explanation for the metallic bond relating to a
human likeness - but it is unrepeatable in polite company...
They were falling-about at the miners group I was at.
Okay - the ends of the periodic table are like monogamy. Then there
is a midband where you get the "flexible social arrangements" which is
the metallic bond. The electrons are not unique to any one atom.
Explaining the characteristics of a metal
- lustre to light / mirror
- conductivity
- ductility
So when you introduce a region of triaxial strain there must be some
effect on energy levels of the bonds.
You could imagine that a strained region could find itself less
strained by making welcome a hydrogen.
Now I never got a chance to talk with a theoretical physicist, but I
suspect hydrogen, with a proton as a nucleus and just one electron -
if that were to get involved in the sea-of-electrons then we would be
talking about just a proton wondering around.
If there were right, that would explain the extraordinarily high
diffusivity of hydrogen in steel. The initial millimetres is in
minutes.
Alexander Troiano of Cleveland was the first to recognise the
behaviour of sharp notches under stress in the presence of hydrogen
being where after a delay for the hydrogen to accumulate there the
hydrogen cracking starts. We visited him - myself and a professor -
and he described aircraft on the Pacific islands would be stood there
nothing going on and there would be a "bang" and the undercarriage
would snap. Clean in two. No warning.
Thinking through it, he "got it" with his tests on notched pieces of
metal hydrogenated.
Back in the 1940's.
There in the early 2000's we were seeing him, unbeknownst to us this connection, about aircraft undercarriages...
I will go suggest to fellow doing those tests about trying a fillet
weld in static stress.
Rich Smith
(photon thinking "I'll not entering that pit of
iniquity")
(one gets in one side of the bed while another gets out
of the other side of the bed)
It is maybe crude and can fail
However the "space" model can brea
--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)