Welding rusty metal?

I have seen a lot of frame work and patch panels being done on rusty surfaces,,,,

I was taught and have always gone the extra mile to sandblast the rust or paint before welding in new metal,,,,

I am not criticizing anyone for the way they build their cars but why not work with clean metal? HRP

 

That's how I was taught too. Just the thought of trying to get a decent weld on something that's rusty - ESPECIALLY a frame - gives me chills, and I don't even consider myself a good welder.
Did you see something recently that freaked you out?
Kindness is a virtue, but you wouldn't be doing anyone, even a friend or HAMBer any favors, by not speaking up and politely reminding them that their lives and others could be on the line.

 

I didn't post this to start DRAMA,,,

I have seen a lot of threads where guys approch the job in a different way,,,,HRP

 

clean metal = better welds

 

Agreed, I was taught to always clean to bare metal before welding.

 

same here, cleaner the better

 

Often overlooked by the less experienced who say "ah ya, it'll weld through that paint or rust". Correctly prepping the surface is a must for good fab work!

 

there was a thread just a few days ago that was tragic to say the least , i believe we all seen it , on the most part everyone tried to help but as things sometimes go it went downhill fast.. not all but some of the trouble was with welding on a dirty surface , im not a professional welder either and lay no claim to be and i to have to start with a clean metal just so i can see how im doing , well that and its just the right thing to do..

 

Back in the 60's at my first repair shop job, we saw alot of not-so-nice, 'brown' metal..."no problem" says the boss, "we just got a fresh box of rust rod"...lol

 

It comes from people who just plain don't know any better, either they were never taught properly or they plain don't care.

 

I think the "death rod" crowd do it on purpose. Much easier to achieve bubblegum welds using rusty steel.

 

I agree, there are a lot of guys and gals out there who never have had any instruction on how to weld, just figured out how to make sparks on their own. "This weld will go right through that rust once I get an arc started" is the mentality.

And the time factor is probably a contributor as well. "It'll weld, why take the extra time to clean it?"

 

welding as in body work, 90% of the work is prep to get good results...

 

I have no idea what any of you guys are talking about

 

HRP,

That frame looks great, but that tri-square and C-clamp, they sure are rusty...

Mikey

 

Freshly sandblasted metal is not exactly "clean" metal. If you have ever TIG welded anything after being freshly sandblasted you will notice that your tungsten will have a little halo type buildup on the end. The blasting media get impregnated into the surface of the metal which then gets burned off, which then leads to a contaminated weld/tungsten. I think the best practice is to still grind the to be welded surfaces with a flap or hard wheel before welding to get it clean, even after sandblasting

 

I have never TIG welded,,,I use a MIG,,,

But from what you say the metal still should be free of rusty and paint,,,. HRP

 

Sure eliminates a lot of curseing if its clean, also keeps the old blood pressure from rising.

 

You'll never see anyone who has been properly taught the fine art of arc or gas welding, welding rusty metal. When I learned to weld (I had to be certified) any blobs, bubbles or chicken shit welds cost you another evening in class :'( I dont get these ratrod guys who LIKE the way their care look with their rusty poopy looking welds. At one point in time during my classes we had to disassemble a boxed segment of (really) poorly welded steel, clean the chicken shit off of it and re- assemble it back to the proper dimensions. When you learn right you learn fast!

 

Even if the MIG weld looks super nice......it can still be easily contaminated. You just don't know until you perform some sort of testing on it. MIG is funny 'cause it is still prone to contamination even when everything is clean. TIG is the purest weld process and it can be contaminated......so you really want to get rid of any issues you have control over.....so Cleaning the metal until it's bright / shiney is a Given.

Metal from the forge can look clean, but a wet saw lubricant contaminates. Rust & paint does too. Mill Scale on a grey fresh piece of steel will also mess up the weld process. No matter how fresh / clean the metal looks, you still need to freshin it up until it's Bright and Shiney before performing a weld procedure.

Flux Core & Arc welds can do a lot....such as go through rust & paint....but really guys....that's out in the field stuff. If you have any ability to clean the material.....then do so.

You can weld shielding the weld with CO2 also, but it doesn't produce as pure of a weld as shielding with Argon/CO2.....thus these little rules like......CO2 is for Beer.....well......it just gives a better weld result / weldment in the end.

Carl Hagan

 

Clean metal=happy welds. I love it when guys get pissed when your like, "might wanna clean that up before you weld". Ive had guys tell me they were just going to turn the machine up and "burn right through it!" Right on man!

 

And gavin is right. Metal that has been blasted, either sand, glass, nutshell....whatever, needs to be flapped after to try and remove as much of the blasting media as possible from the steel. It shows up the most during Heli-arc welding but still affects arc (stick) and mig welds. there is still stuff in the steel that don't belong there!

 

Right on Carl....Nothing but straight argon for me, even in my mig setup. I just just switch the big bottle from machine to machine. Cleanest coolest welding ever!

 

This is not a subject that should even be "discussed", it should simply be clearly stated that you should ALWAYS weld to clean metal---period.

 

I agree sorta with roddiron, but lets hope that others who don't know the Holy Secrets of WELDING, might read this and ask for help (maybe some backyard welding lessons) or maybe think twice about welding something that should be welded by someone who knows how do it.

 

Tell more about the straight argon set-up for mig. I have heard good things about it, but the guys at the welding supply I go to acted like I was a moron when I asked them about it. Several of my welding instructors mentioned using it, and now you have too. Makes me think, just wanna know more about it.

 

The sad deal here is most backyard welders don't really know any of the general rules.

The weld nasty, using cheap welders & really just the cheapest way out.

People laugh mainly because of the 'cost'...not the idea. Argon / CO2 can be used in a few different areas.

CO2 can shield a mild steel weld, but Argon/CO2 cost more but gives better quality. Argon/CO2 at a 75/15% ratio is good for mild steel using the Short Circut process. Argon/CO2 at a 90/10% is good for mild steel using a "Spray Arc or Spray Transfer" process. 100% Argon is used for Aluminum.

It's all money really. Carl Hagan

 

I've gotten into the habit of hitting the metal with non-chlorinated brake cleaner after I clean it or flap it. I haven't noticed any ill-effects.

Should I not be doing this for any reason I may not be aware of?

 

I'm no brake cleaner expert, but I would imagine that is some type of oil.....which leads us back to the beginning......Bright / Shiney & Clean.

Oil, paint, rust, mill scale, a drip of tungsten, a piece a slag, some spatter falling out of the nozzle into your weld......It's all contamination.

I use a flapper wheel until it's bright & shiney. Then weld.

Carl Hagan