can i weld stainless to mild steel?

[steveo3002]

i need to join stainless to mild steel , i have rods suitable for either

it doesnt need to be a awesome job...can it be done and what rods should i use

thanks

 

[matt1978]

Depends on Grade on the parent material (Stainless) and what you need it to do. In general though you could use either 309 or 312 rods, with no problems. Don't use normal mild steel electrodes.

 

[Hitch]

309 rods will do nicely if you have them.

If its a bit of a botch job, and you have bothing else to hand, the mild steel will suffice.

 

[aametalmaster]

Depends on Grade on the parent material (Stainless) and what you need it to do. In general though you could use either 309 or 312 rods, with no problems. Don't use normal mild steel electrodes.

Why not use mild steel rods? Just wondering...Bob

 

[matt1978]

Because the weld could/would go rusty in time. Especially if the job is left outdoors.

It depends on the grade of Stainless he is welding it too, if its only 304 Stainless, them MS rods wouldn't be so bad, but anything higher than 304 he should use a 309 or 312 electrode.

 

[steveo3002]

no idea what grade ss it is.....its a part of a gearlinkage on a car so nothing exoctic i guess

 

[matt1978]

No I doubt it is.........

Use your Stainless rods then.

 

[tigmann]

The main reason for not using carbon steel electrodes is due to the
formation of a seriously undesirable defect condition known as
liquation cracking which results in very low joint strength.

 

[tigmann]

The "golden" rule is you can deposit stainless steel on carbon steel and
produce a successful joint, but you can't deposit carbon steel on
stainless without seriously depleting the mechanical properties of
the resulant weld.

 

[TechnicAl]

That is definitely wrong.
There are many different grades of stainless, some would be Ok, some would crack

 

[dutchman]

WOW! Interesting stuff there about the Schaeffer diagram.

Keep writing posts like that guys. You too Tigmann!

All this is very educative

 

[tigmann]

I thought this forum was for practical suggestions which may be applied to everyday technical problems encountered by both novice and the experienced welder alike, not a lesson in rocket science!

I am well aware of the significance of austenite and ferrite as well as martensite, which influence differing mechanical properties in fusion welding, but to get back to the original thread,you can deposit an ordinary 18/8 on carbon steel and make a rasonable weld albeit somewhat depleteted in corrosion resistance, but it will still have some usable mechanical strength.
This is quite useful when welding thin material such as car bodies with TIG or stick due to the differential in melting points the s/s deposit produces a weld with a lower heat input, which helps lessen distortion as well as giving a smoother profile.

If you don't believe me I suggest you try it for yourself, your never too
old to learn, and you learn something new every day!

 

[snowcat]

http://www.wear-management.ch/?path=root+repairwelding&lang=en

This is the schaeffler diagram which predicts the structure of steels (and therefore the properties) by use of Chromium and Nickel equivalents.

The ideal structure for a crack free weld is the area austenite + ferrite (A+F). 309L is 23 Cr 12 Ni (approx) so it sits slap bang in the middle of that area. If you use 309L on ms you might get 20% dilution ( 18 Cr 9 Ni) so it would still sit in the "good" area.

If you start with a 308L (20/10) the same dilution will give you 16/8 which is starting to get close to a "dodgy" area

Thanks al thats really refreshed my memory... the importance of haveing a basic understanding of the propertys of meterials is a basic rudement to every welders ability to do a decent job......

 

[lovelectricity]

it depends on if a failure is important, on the pneumatic can crusher it wasnt. the nut on the end of the piston rod was stainless the crushing plate is mild. it was welded with 6013, but it is always in compression and is ok after being left outdoors after around 7000 crushes and about 6 months(no problems yet). (although is painted). in a stress enviroment it may fail. i only did this because it wasnt important and was done in my back garden, the grades are important if it is vital it stays together. for me if it fails( probably after ive rotted away), then someone else is gonna have to weld it back on. make your own choice on what grade you use but the advice above is sound if it needs to last together, but decent welds can be made with gp rods but may leave you in years to come, in netural on a busy motorway. (it would brown my pants), weldequip pair of new pants please, not easily brownable or burnable if such a thing is possible, cheers

 

[tigmann]

The proof of the pudding is if it does the job "what the hell"

It seems Dr. Shaeffler is not right about everything in welding!
Although his Cr Ni diagram is useful in general applications it should be remembered that it is only an approximation of resultant constituents and other alternatives are sometimes suffice for the job
in hand.

 

[matt1978]

There's a "Correct" way to do things and I think AL was saying the right and proper way.

That's not to say that corners can't be cut and rules not bent in real life, but if you know how it should be done by the rule book then you can make your own decisions depending on your own application.

 

[Hitch]

I am going to agree with both tigman, and TechAl.

I have been doing a fair bit of disimilar stuff recently. If you really dont care, and you just want it stuck together, a bit or standard steel wire/rod is adequate. If you want it to last forever, take strains, movement, its important to use the correct stuff.

In some cases, a bit of a compromise is worth it for the money saving costs.
I dread to think how much it would cost to buy a reel or box of every single consumable you should be using.

 

[aametalmaster]

Here is what i know, right or wrong. I was a sheetmetal worker and i made industrial sifters for another company. The sifters were SS skinned with carbon steel insides. The skin was 3/16" thick and the insides were 1/4" and 1/2" thick carbon steel. Everything on the inside was welded with a regular mig with regular steel wire. Everything on the outside was welded with SS wire. These things were industrial shakers that were designed to be used daily. I didn't design them and was just welding them with what was on the blueprints. They had zero failure rates in the 8 years i was there. So just my thoughts...Bob

 

[snowcat]

I am going to agree with both tigman, and TechAl.

I have been doing a fair bit of disimilar stuff recently. If you really dont care, and you just want it stuck together, a bit or standard steel wire/rod is adequate. If you want it to last forever, take strains, movement, its important to use the correct stuff.

In some cases, a bit of a compromise is worth it for the money saving costs.
I dread to think how much it would cost to buy a reel or box of every single consumable you should be using.

compleatly agree all depends on the job, often i get ivolved in welding castings and it depends on the way the wind blows to which method i tackle it with.....that said I like to here the 100% by the book method so if it is something vital then thats the route i can follow...

 

[lovelectricity]

i agree it is possible to do many things, that aren't strictly right. the questions are, a)is it important?, b)how long does it have to last?, c)is it for yourself, and d)what is the best way of doing this bodge? i dont like bodges but when needs must, we need to cut out the home users unobtainable methods and say,how it should be done, what has been done and what could be done.(taking into account no loss of life limbs,equiptment or money). feel free to add to the 'questions' or the 'no loss of'. the use of the words as far as is reasonably practicable, spring to mind in the health and saftey world.