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

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  

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  

you can head over to weld.com and get connected  with us directly through the members section  

as well as you can head over to the members  forum where you can ask questions and our  

advisors will gladly help you thanks  for watching we'll see you next time

you