what's up guys it's jeff ray feature guest host here with weld.com on today's episode we're going
to be welding chromoly tubing for beginners we're going to talk about chromoly tubing as well as we
got a couple of pieces here we're going to prep and weld out for you today so let's get at it
we're going to be getting into what chromoly tubing is where do we use this material and
what applications it's used for but before then we're going to tell you a little bit
about chromoly tubing today we're going to be welding on some 4130 chromoly tubing 4130
chromoly is a chrome alloy steel with a low carbon content it has around 0.25 molybdenum content
for strength the word chromoly comes from the combination of chromium and molybdenum the two
major alloys that make up this material the 30 and 4130 designates the grade number and has about a
point three percent carbon by weight chromoly is a steel alloy that is stronger than regular steel
it is mostly used in bike manufacturing roll cages race car chassis and also in aviation due to its
strength you're able to minimize the tubing wall thickness that gives you a lighter base material
rather than regular mild steel unlike the other materials chromoly is the most cost effective
while still maximizing the strength at the same time when welding on chromoly anything under 120
thousandths doesn't necessarily need to be preheated anything thicker than that should be
preheated between three to four hundred degrees before welding the most commonly used filler
when welding chromoly would be er80s d2 but you can also use er70s2 and er-70s6 as an alternative
they're also acceptable as a reminder to never rapidly cool a weld by dunking it in
water always allow the weld to cool slowly to prevent cracking we're trying to maximize the
strength of the material as well as the weld so we don't want any cracking with that being said we
got a couple of drop pieces of some 4130 chromoly tubing here that we're going to be welding on so
i'm going to go ahead get these things cleaned and prepped and we'll get them welded let's get at it
we got our scrap pieces of 4130 chromoly tube prep this is some inch and 5 8 0 83 wall 4130 chromoly
tubing i got this piece that's going to go on the end here it's not perfectly perpendicular
or nothing we didn't try to make these these are just cuts that i had laying around we cleaned up
then we'll put that that one there so if there's anything else you guys would like to see us do
with the chromoly tubing different copes different fits stuff like that let us know in the comments
but down below but we're gonna go ahead get the machine turned on get this stuff tacked together
make a couple of welds so let's get at it we're ready to get this stuff tacked we're gonna go
ahead get the bottle turned on we're gonna use 100 straight argon if you notice whenever i open
my bottle of argon i always stand off the side of the regulator to ensure that say you didn't
tighten this thing down you just threw it on here and then grab a wrench you turn that on the
pressure of that bottle could possibly blast that regulator off and whack you right in the chest
so always stand off to the side when turning on the bottle we're gonna get the machine turned on
we're gonna utilize the everlast power tig 210 ext it's on 45 amps we'll turn it up to
we'll start with 90. that should be good we're running dc negative but high freq tigs start
with the foot pedal so let's go ahead and get this stuff tacked together get a couple
of welds made we're ready to tack this stuff now i'm going to be utilizing some er 70s 2
1 16 wire i've got the furik mk14 cup with some e3 332 tungsten ready to tack these things up
i'm going to grab the first one here with a piece of tape just make it a little easier
put the fit there
just helps when you're by yourself
to have something to hold your fit so let's get this thing tacked off a couple of spots
uh
got this thing tacked now i want to talk about the tacking of it a little bit when welding it
it kind of welds like carbon steel does but say when you're welding carbon steel you make attack
you can hit the piece and manipulate it some with the chrome moly it does not have that give
the tacks are just going to break the material is strong tensile strength strong so that that
tack is strong but it's very fragile at the same time so if i try to hit it to move that piece it's
just going to crack as well as gas coverage you see i got the big cup on here i want a lot of
gas coverage long post flow we don't want to cook this stuff either so we're ready to get into it
so
got both worlds made they went great i had a little gust of wind blow by maybe a spot
of porosity in there somewhere but like i said i'm using a big cup i want a lot of gas coverage
gas coverage is a big thing with this stuff it welds a lot like carbon steel but i enjoy welding
this stuff a lot more i do enjoy welding carbon steel but i love welding chromoly the fit up on
this stuff can make your weld easier or harder on you because this is thinner walled tubing it makes
for having a good fit up to have a good weld so always try to have the best fit you can to
ensure you have the best weld you can especially when you're going for strength we want good fits
to have the strongest weld possible now my tungsten direction i'm going to be pushing
the puddle as this is molten steel so it's going to flow it'll have a direction of flow per se and
when i get around the curve here if i don't turn the head just right the puddle might favor
one side or the other that's just something i found out from welding this stuff just doing this
stuff more and more you know if it's not something you do all the time practice practice practice
and that's how you're going to get more proficient at welding this type of stuff as well as
fabricating and fitting this stuff up so a lot of the times when welding this stuff it's chassis
work or you know bicycle frame stuff like that where one piece of pipe is gonna intersect from
one piece to another so essentially it'll be closed off and when i go to weld that piece the
oxygen inside of it is gonna start to expand when it heats up and it'll start to actually blow out
in the fit of your weld and you can't really seal that weld up because that oxygen inside
is expanding and pushing out of there creates a lot of porosity and it's a mess so whenever you do
do chassis work and stuff like that you'll drill a hole at the intersect point that way it allows the
air inside of it to pass out and not expand and have a cavity in there where it's going to blow
your weld out of that that joint there and create a bad weld so that's one of the major things
i've noticed when working with this stuff because it is a big problem with it in chassis
work that's the type of stuff you're going to encounter thanks for watching until next time
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you