stainless steel mig welding...help please

[viper]

hi all,

im new here and need some advice.

im building a spcace framed chassis out of stainless 25mm x 3mm thickness tube,

iv come to weld the first lot of the chassis.

i have a clarke 135 mig with argon gas and 0.8 stainless welding wire

i tryed to weld a bit today and got nowhere

All i got was massive blotches and i couldnt get it to realy weld at all

also the tip then melted, i replaced it and turned the power to the lowest setting and it did the same. do i need special tips for stainless and gas welding? as the tips im using are the ones that came with the welder

could you please give me some advice as iv never welded stainless before

Thanks

 

[TechnicAl]

Argon

wrong gas

 

[viper]

Argon

wrong gas

realy, the guys are machine mart said id need it.

what gas should i be using please?

 

[shenion]

Argon is right if your are using disposables. Argon will produce tall welds though.

You can use argoshield light if that is all you have. You want as low CO2 as possible.

If you are melting tips, you need to up the wire speed and use a larger work/torch gap.

 

[Wozzaaah]

At the risk of sounding rude, you're trying to run before you're even crawling.
You're fabricating something that you'll be relying on to be made strongly and safely but you don't have the necessary skills or the correct equipment.
Get some scraps and practice, practice, practice before attempting the chassis.
Your machine is a little small too, a 150A machine would have been more suitable as you'll need yours on pretty much full power for 3mm thick stainless.

 

[Drains]

And at the risk of sounding unhelpful - you'd be MUCH better off welding that with Stick rather than Mig. Much easier to get good reliable welds (once you've learned to weld).

 

[backpurge]

As Al says argon is totally wrong, you will not get anywhere near the penetration you require for this job, the welds will just lay on the top of the material, you need argon + either 2.5% CO2 or 2% O2

 

[viper]

been out for the whole day practicing and dont think im getting anywhere

im going to take peoples advice and try nad get hold of mild steel, i know i can weld that i just cant seem to get it to penatrate with the stainless.

Thanks for all your help and advice even if some of it was slightly down putting

 

[Wozzaaah]

Not down putting at all, just sensible.
You're risking your life and that of others, best to get it right eh?

 

[Scamp]

Trawling through the old memory banks and I seem to remember doing a load of Stainless Steel MIG welding when I first started in the trade. I'm sure I am correct in saying that a Helium mix gas should be used.

 

[Ed.]

Hi, if your using a a 135amp MIG, then you are definitely underpowered in the voltage and amp department if you are using straight Argon, you will need to get a lot more heat into the weld bead, and that you won't be able to using that gas and MIG setup, as you can't change your MIG welder, you might be able to change your gas mix, an Ar/He mix will give you the hottest heat, or a Ar, CO2+O2 mix would be next. I think the guys at the welding shop gave you a bum steer suggesting the 100% Ar.

The only way you might be able to get anywhere with what you got now, would be to try droplet deposition. But as you aren't very experienced in MIG welding I do not like your chances of doing a successful weld, especially if it is a structural weld. I used 100% Ar, for about 10 years using a 235 amp MIG and the results were OK but not brilliant.

Not trying to put a downer on your setup but in my opinion it isn't suitable for what you are trying to do and if your life depends on structural quality... don't do it. Just my 2 cents worth.

 

[backpurge]

Have given this a bit more thought and have to agree with most of the above comments
I think you would be better off using a different process, MMA or TIG could well be your best solution
If you are determined to continue with MAG you need to get your power right up, don't fall into the trap a lot of begginers do with MAG and think that travelling slow and building up the weld size gives you a stronger weld, it doesn't you need to travel quickly
Make sure your joint fit up is good with no gaps
Get your gas mix right, either Ar+O2, Ar+CO2 or Ar+He+CO2, no more than 2.5% active components or you will get excess oxide build up along with the potential for carbon pick up
And above all practice, practice, practice. Post some pictures if you can then we can be a bit more subjective with our comments

 

[Ian James]

I will second or third the coments on gas i have just made a spare wheel carrier out of 50x50x2 stainless box section because it was left over from another job as i mainly weld mild sreel i use cugar 5 and was ending up with dark black weld witch was down to the gas i believe i did try pure argon as i have some in because i am having a play at welding some aluminium with the mig using a spool gun the pure argon on stainless leaves a shiny weld but it stands proud ond apears not to flow as you weld.

 

[chunkolini]

Have a look at this thread, I was having problems welding stainless and tried several gas mixes, there are photo's on page three showing the difference with the mixes of gas, I ended up sticking with argoshield.
http://www.mig-welding.co.uk/forum/showthread.php?t=19083

Hope that helps.

Chunko'.