This is really getting some odd information presented here. The filler
rod intended for use with 4130 tube used to build a fuselage is MILD
STEEL. The weld is stronger than the tube even though welded with MILD
STEEL. Choices for filler are things like ER70s-6 or -3 or -6. And
several variations, some with additions to the designation like D2. All
will do the job from a metallurgical point of view. I find ER70s-6 to
suit me best with both Oxy/Acet or TIG, though you might want to sand
the copper plating off before welding with it (some find the copper
interferes with the flow of the filler in the molten puddle).

The only time 4130 should be welded with 4130 material is when the part
is going to be heat treated. A novice welder can get into trouble with
undetectable cracking when welding with 4130 filler wire. Heck, even the
experts can find problems with 4130 material used for filler.

A small side note, there are fillers that exceed the strength of heat
treated 4130 that weld as smoothly as if shaping soft butter with a
table knife. You can weld the part more easily than you can with mild
steel then heat treat with no chance of cracking or embrittlement of the
fillet. Sorry, TIG welding only...and expensive.

--
Bruce A. Frank, Editor "Ford 3.8/4.2L Engine and V-6 STOL
Homebuilt Aircraft Newsletter"
| Publishing interesting material|
| on all aspects of alternative |
| engines and homebuilt aircraft.|


"Matthew P. Cummings" wrote:

On Sat, 30 Aug 2003 13:30:40 -0700, Joe Maj wrote:

I was one of those instructors, and I always state that R45 is
completely satisfactory for gas welding 4130 steel. I use it myself.

The older guy giving it said that nothing but 4130 is acceptable now, and
furthermore you do not need to stress relieve, but then a younger guy,
maybe you, disagreed with what he said. In fact, a young guy who was
supervising the welding said that if you followed the older guys advice
you would blow up your shop, cracking the valves before attaching the
regulator.

What did people think of the OSHA-industrial-grade lecture on gas
welding safety? Having listened to it twice a day for a week, I think

I thought for a person who's never been behind the torch it was
appropriate, however, if you've welded it was much too long.

don't express an opinion, we'll all have to go through that again next
year.

I suspect you need to give it since you have a lot of people who've never
welded before. It could be shortened up by not parroting what the video
tape says.

What I believe needs to happen is to have consistency between instructors,
as was I found the EAA welding forum to be next to worthless due to the
conflicting information. How is a newbie to differentiate between the
instructor who says do this, and then he moves on the hands on part and
they say don't do that. Your forum in my opinion created confusion in the
minds of some of the participants, or so I noticed when I was watching
them.

One of the most outstanding issues was if you attended any of the other
welding forums, Budd's or Kent's, what they did and said was not at all
what the EAA said. I'm not good enough to judge the correctness of what
the EAA instructors said, but I will do what people have been doing for a
very long time in contrast to what the EAA instructors said and as the
other two whom I respect have said.