what is diff. from mig welding mild steel as opposed to stainless. is it even safe to mig weld stainless.

might attempt to make an exhaust soon, but i only have experience mig welding mild steel. but might get a stainless kteller kit to put together.


Modified by postman at 2:51 PM 5/13/2008

 

The gas is different, that is the first thing, I use a tri mix that works OK for stainless and mild, but I recomend getting seperate gas for just stainless.

Also check the grade of stainless because you want to use the corresponding wire to match it, like for 304 stainless use 308 wire, but if you are gonna weld stainless to mild use 309??? I think thats the right way. 321 wire for 321 stanless and 347 for 347, Im not sure about 409 stainless though I don't think they make a 409 mig wire but they do make a tig rod for it.

 

technique and process are the same though.

 

Just don't use mild steel filler rod on stainless, you'll create hexavalent chromium which is among the most toxic byproducts of any welding process. OSHA freaks out about even a couple parts per million. the stuff is nasty, like napalm for your lungs.

 

if it's your first time welding 304 try using 308Lsi wire. when i first started welding stainless i found it easier to get a good looking weld profile with it than regular 308L wire because the of the silicon content. It easier to get than colorful weld everyone likes to see. also at work we use a 98/2 argon/C02 mix w/ this wire because trimix is $$$$ and most of the stainless stuff is thinner gauge anyways.


Modified by KENetics1 at 12:21 PM 5/14/2008

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by KENetics1 &raquo;</TD></TR><TR><TD CLASS="quote">if it's your first time welding 304 try using 308Lsi wire. when i first started welding stainless i found it easier to get a good looking weld profile with it than regular 308L wire because the of the silicon content. It easier to get than colorful weld everyone likes to see. also at work we use a 98/2 argon/C02 mix w/ this wire because trimix is $$$$ and most of the stainless stuff is thinner gauge anyways.


Modified by KENetics1 at 12:21 PM 5/14/2008</TD></TR></TABLE>

It's 98%argon 2%o2 not co2 and it's a spray arc transfer mix. Spraying thinner stock is not recommended and can really only be pulled off at super fast travel speeds in the flat or slightly horz positions even then its sucks a little bit and is only done because there is about zero spatter save the cold start. Since I doubt the guy is going to buy a positioner to weld his exhaust I HIGHLY suggest he gets some trimix and short circuit it at around 19V 190WFS.

http://www.millerwelds/education/calculators

Now that I've given that advice I'm going to go to sleep, wake up and weld 12gauge with lsi wire and 98/2 at a setting more suited for 1/4in. It's ok though I have automated rollers yo

GMAW(mig) welding stainless steel is a little bit different than welding mild steel. When making a butt or fillet weld the puddle will want to stick to one side and cold lap into the other side. Easiest fix for this it the make a forward/backward whip motion. So just weld forward, weld backward, weld forward in say 1/16-1/8th in steps.

Maybe someone can explain that better than me.


Modified by ManBearPig4silly at 8:56 PM 5/14/2008

 

[QUOTE=ManBearPig4silly]

http://www.millerwelds/education/calculators

should be http://www.millerwelds.com/education/calculators

Cool link thanks for posting

 

so basiclly get a trimix and use a stitch pattern

 

haha I'm so internet retarded

If by stitch pattern you mean

(-&gt;direction of weld)-&gt;pause-&gt;pause-&gt;pause then yes sir! don't pulse the trigger and try to get a tig looking weld by stacking tacks.


Have fun.

 

So 308 couldnt be used for mild steel to 304 or 321? It should be a 309?

Not to threadjack but what about 321 to 304? 308L should work, correct?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by coll9947 &raquo;</TD></TR><TR><TD CLASS="quote">Just don't use mild steel filler rod on stainless, you'll create hexavalent chromium which is among the most toxic byproducts of any welding process. OSHA freaks out about even a couple parts per million. the stuff is nasty, like napalm for your lungs.</TD></TR></TABLE>

So all these guys welding stainless manifolds with mild steel flanges should be dead?

Does the same go for welding mild with a stainless rod?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by robbbby &raquo;</TD></TR><TR><TD CLASS="quote">

So all these guys welding stainless manifolds with mild steel flanges should be dead?

Does the same go for welding mild with a stainless rod?</TD></TR></TABLE>

no, because they use ss filler for mild to ss weld joints.

if you're welding steel to steel then use steel filler. If mild to ss then use correct ss filler.

 

FYI, stitch welding means welding a short interval, skipping a short interval, then welding again. NOT repeatedly tacking.



That is a stitch weld.

 

to add to what k24em2 just posted another term for "stitch" welds is intermittent welds. The welding mumbo jumbo they teach you in welding class

 

what k24 has is only used to control heat from what i thought. thats not what i was tought a sticth weld was. stitch weld - the only way i can explain it is kind of like zigzagging between your joints of what your welding. but hey im no welding expert

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by postman &raquo;</TD></TR><TR><TD CLASS="quote">what k24 has is only used to control heat from what i thought. thats not what i was tought a sticth weld was. stitch weld - the only way i can explain it is kind of like zigzagging between your joints of what your welding. but hey im no welding expert</TD></TR></TABLE>

The stitch welding method I posted is designed to save time and money in welding costs by reducing weld time and consumables.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by postman &raquo;</TD></TR><TR><TD CLASS="quote">what k24 has is only used to control heat from what i thought. thats not what i was tought a sticth weld was. stitch weld - the only way i can explain it is kind of like zigzagging between your joints of what your welding. but hey im no welding expert</TD></TR></TABLE>

it's called weaving the zigzagging your talking about. what ManBearPig4silly was trying to explain to you is just weld straight then pause, as in stop your hand but still holding onto the trigger, and move again. anyways if your welding an exhaust you don't want to "stitch" it, you want to weld it all the way around. you can weld it in portions then turn pipe and weld etc...