Corrosion at Aluminum/Steel Junction

"Mark Andrew Spence" wrote

The TICONDROGA and SPRUANCE class ships had aluminum superstructures which
were welded to a "fusion bar" which consisted of a piece of very clean and
smoothly-machined piece of aluminum FLAT BAR joined to a very clean piece
and smoothly machined piece of steel flat bar via explosive charges.

What was the purpose of the explosive charges? (besides, to go "bang" g)
--
Jim in NC

I am now more or less "trespassing" here but I would like to give an
explanation to this question.

The very smooth metal surfaces (bars), aluminum and steel are placed one on
top of an other and the explosive charge is placed, I guess above the
aluminum bar? Does this process take place in some kind of a purpose built
explosion chamber or are the materials simply buried underground (the weight
of e.g. a thick layer of sand would give enough resistance) to be fused, who
knows?

The idea is, that the detonation creates shock waves so intense, that the
metal atoms of the contact surface (layer) area are a sort of mixed
(knocked) together, hence the term fused. The process is probably called as
explosion welding? The created bond is very strong and there is no room for
any moisture to get in. That is why the corrosion can't take place between
the dissimilar materials. At least I figure this to be the case. The Mark
Andrew Spence may give more accurate explanation.

JP


"Morgans" wrote in
...

"Mark Andrew Spence" wrote

The TICONDROGA and SPRUANCE class ships had aluminum superstructures
which were welded to a "fusion bar" which consisted of a piece of very
clean and smoothly-machined piece of aluminum FLAT BAR joined to a very
clean piece and smoothly machined piece of steel flat bar via explosive
charges.

What was the purpose of the explosive charges? (besides, to go "bang"
g)
--
Jim in NC

"Morgans" wrote in message
...

"Mark Andrew Spence" wrote

The TICONDROGA and SPRUANCE class ships had aluminum superstructures
which were welded to a "fusion bar" which consisted of a piece of very
clean and smoothly-machined piece of aluminum FLAT BAR joined to a very
clean piece and smoothly machined piece of steel flat bar via explosive
charges.

What was the purpose of the explosive charges? (besides, to go "bang"
g)
--
Jim in NC

To make a compression weld.

Since steel and aluminum melt at different temps you can't heat weld them
like you would with normal steel-steel or heliarc(sp?) (heat weld in a
controlled atmosphere) like you would aluminum-aluminum.

"Morgans" wrote:

:
:"Mark Andrew Spence" wrote
:
: The TICONDROGA and SPRUANCE class ships had aluminum superstructures which
: were welded to a "fusion bar" which consisted of a piece of very clean and
: smoothly-machined piece of aluminum FLAT BAR joined to a very clean piece
: and smoothly machined piece of steel flat bar via explosive charges.
:
:What was the purpose of the explosive charges? (besides, to go "bang" g)

It's a method of driving two different metals together in such a way
that they sort of blend into each other rather than having to be
welded, bolted, or some such.

The same process came to be used for coins when we switched from
silver to copper-cored coins.

--
"The reasonable man adapts himself to the world; the unreasonable
man persists in trying to adapt the world to himself. Therefore,
all progress depends on the unreasonable man."
--George Bernard Shaw