On Wed, 10 Aug 2016 16:32:38 -0400, wrote:

On Wed, 10 Aug 2016 12:59:58 +0700, John B.
wrote:

On Tue, 09 Aug 2016 23:40:45 -0400, wrote:

On Wed, 10 Aug 2016 10:19:05 +0700, John B.
wrote:

On Tue, 09 Aug 2016 21:38:50 -0400, wrote:

On Wed, 10 Aug 2016 07:32:39 +0700, John B.
wrote:

On Tue, 9 Aug 2016 06:37:42 -0400, "Jim Wilkins"
wrote:

wrote in message
news:dfeiqb1ob8tjbbij2le2ufknqpi15bafb2@4ax .com...
...
All of the aluminum on my plane is 6061T6 - rivetted.
All flight surfaces and flight structures.

Aluminum boat trailers are routinely welded.

What's the difference?
--jsw

The boat trailer is probably not made from 6061 aluminum :-)
Actually, it is.
See
http://www.easternmetal.com/pdfs/alu...components.pdf

I can't tell from the photo but I seriously doubt that a welded
trailer would have been built from 6061T6 as the materials list shows.

If for no other reason than the area around every weld would have
magically lost about half its strength (ultimate tensile strength).
Why would one want to built a trailer of relatively high priced, high
strength, aluminum and deliberately destroy the strength of the
aluminum?
My son-in-law has an aluminum boat trailer made of 6061T651 - some
parts are welded, some are bolted. Being a high end factory built
trailer the weldments MAY have been heat treated - but T6 or T651
returns to about a T4 in less than a year after welding, and keeps
getting better from there.

Which is partially true. Although it isn't quite that simple. The
ageing/artificial aging process is largely dependent on the pre aging
solution heat treatment. If you melt 606T6 it looses much of its pre
welded properties and if the ageing process doesn't start from a
maximum solution treatment than there is no way of telling what is
going to occur See" https://app.aws.org/forum/topic_show.pl?tid=7392
for a more in depth discussion with additional references.

And, while it is "probably good enough for a fish boat" as my Maine
State relatives might say it could be a different story for a flying
machine :-)
Which is why aluminum parts on planes are very seldom welded - while
6061T6xxx aluminum is very commonly welded for trailers and
applications like dump truck boxes, feed trucks, garden carts, etc -
and even boats, both large and small.

Yup :-)

I spent about 20 years in the airplane business and thinking back I
don't remember many, if any, welded aluminum bits and pieces.
--
cheers,

John B.