NASA published an advisory many years ago that was reprinted in Sport
Aviation , I don't have the article at my fingertips , as I remember , NASA
stated that any 4130 weld assembly that was TIG welded and used on Aircraft
should be post heated via Oxy/Acet , anyone who has ever done any welding
and especially ARC welding must know and has experienced the tension that
has built up after the weld has cooled , just a pinch of common sense would
tell you that this tension load will be there for the life of the weldment ,
to raise the temp. of a given cluster up to a point that allows that cluster
to seek it's sweet spot without that locked in tension and possible
premature failure would only make common sense , NASA is far from perfect
but they were on the money with this advisory .
I don't know how many people that write books on welding have actually
worked on the floor with real airplanes and have actually welded on
commercial airplanes , I have seen many lineal inches of Oxy/Acet weld laid
down and never saw a crack or fracture of that weld that occurred on the
floor even before an assembly was painted , I have seen many TIG welded
assemblies that would crack shortly after welding and again before they saw
paint , if you have an engine mount that needs a small amount of machining
and the machinist is damaging high speed steel end mills with hardened 4130
, this has to be very telling , it's been a few years since I worked for a
Jet engine repair station , as I recall , all welded parts were placed in a
oven and slowly raised to about 1020 Deg. F. and held at that temp. for 3
hrs. and then the temp. was dropped at a certain rate for several hours ,
they didn't do this for there own pleasure , this was FAA mandated .
Best
Phil Lohiser
"wright1902glider" wrote in message
...
While browsing a bit more of that "good 'ole internet wizdom", I ran
accross this page:
http://www.ihpva.org/com/PracticalIn...materials.html
Its a human-powered vehicle website, but on this page, the author
seems to think that 4130 cro-mo steel can't be welded with an oxy-
acetylene torch. Does this sound right? It was always my belief that
we've been OA welding airplanes out of the stuff for decades. Who is
wrong on this point?
Harry "I'm still stuck in the wood-age" Frey