Stainless steel welding

[shade tree welder]

A customer of mine owns a car wash in town,he brought by a s-steel pump motor rack that was made of 2" X 1/8" square tube. He needed to extend the 4 legs 4" taller and cut the rack down to a smaller size.I cut the legs in half and added a 4" piece in between and cut the other 4 crossmembers down to his measurements and welded back up with my m-210 and.30/308L wire(only wire my lws had in 2# spools) and tri mix gas. The welds turned out great, but they look like a regular mig weld on mild steel, no pretty s-steel color to them.This is the first time I ever welded s-steel on my mig,could have tigged it(i am fairly good at tig) why did the welds come out that color? Is there any way to tell what grade of s-steel you are dealing with? I am thinking maybe wrong wire for this type s-steel?

[yorkiepap]

Hey s-t-w,
I don't think I would be too concerned with color. Since this is a car wash application, & subject to winter salt/cal chlor., I probably would have opted for 316/316L. Unless the owner had the original invoice of material used for the car wash system, it would be difficult to determine SS grade used.

Denny

[bretsk2500]

my employer has 2 carwashes that I maintain... one has been in operation for 23 years and it's pump racks are mild steel. the other, much newer carwash is pretty much all 304 stainless. did you overheat the stainless? even my little lincoln will give the rainbows when welding up thin things that were broken.

I've found i have a love-hate relationship with stainless and carwashes. i like to weld stainless, but i do get sick of welding up new stress cracks in the automatic's track. not a single weld of mine has failed, but nearly EVERY factory weld has. I even had to completely disassemble and re-weld the automatic carriage.

[letzgoracin301]

the only way to tell what grade without paperwork is PMI. at a smooth 30,000 for a PMI gun.

[1havnfun]

304ss vs Steel

The fastest easiest way to determine if the rack is 304ss or steel.

use a magnet, about a buck.
304ss is non magnetic
steel is very magnetic.

if the magnet doesn't stick then you have a 300 series stainless.
To determine 304 vs 316 vs 321 vs 347. you need to spend the big bucks.

[BoxCar]

I know that most of the time when I weld stainless steel I run the welds over a wire wheel to take the burn marks off to get that nice shine look. If you used stainless mig wire then using the wire wheel would work. Just a thought