stainless to mild steel

  1. james butler

    james butler Member

    Messages:
    1,243
    Location:
    birmingham england
    good evening everyone.

    im making a fuel filler neck for my car and have managed to get a piece of 38mm tube bent to the shape of the filler neck and at one end a 54mm tube is welded on but i need to weld the filler cap socket made from mild steel onto this end (because stainless ones dont seem to exist).
    is it ok to mig weld it straight on with mild steel wire as i dont have the gear for stainless.

    i made the same pipe before but all out of mild steel and worked well but this will be the first time its mostly stainless.
     
  2. Hood

    Hood Forum Supporter

    Messages:
    9,634
    Location:
    Carnoustie, Scotland
    Welding steel to Stainless with steel rods can make a brittle weld in my experience but that is with stick and not mig so can't say for certain it would be the same.
     
    james butler likes this.
  3. james butler

    james butler Member

    Messages:
    1,243
    Location:
    birmingham england
    i should also mention the tube wall thickness is .9 ish mm
     
  4. Paul.

    Paul. Moderator Staff Member

    Messages:
    6,162
    Location:
    Northampton. UK
    It'll be fine, if you were building a bridge it would be a different matter, if you really wanted to make a job of it get it tigged with a 309 filler, but for this application its not really necessary.
     
    pdg and james butler like this.
  5. anto44

    anto44 Member

    Messages:
    1,253
    Location:
    ireland
    You should be fine welding it with mild steel wire. I've often welded stainless steel to mild steel on car exhausts and never had a problem. I know its technically not correct to do it but for the application it will be plenty strong as long as you get a decent weld
     
  6. james butler

    james butler Member

    Messages:
    1,243
    Location:
    birmingham england
    would be nice to get it tigged.
    its going to be hidden up in an arch where no one will see it so probably not worth it but cheers anyway:thumbup:
     
  7. Arclikeharrypotter Member

    Messages:
    1,034
    Location:
    Northampton
    The best welds are always the hidden ones!!
     
    anjum likes this.
  8. Richard.

    Richard. Member

    Messages:
    18,197
    Location:
    Cambridgeshire
    It does the opposite hood it is a more ductile less strength weld. The only reason it's not too great using a mild steel consumable is it will rust where as a fully austenite joint with an over alloyed filler won't. In most cases this been one it shouldn't hurt with a squirt.
     
  9. Hood

    Hood Forum Supporter

    Messages:
    9,634
    Location:
    Carnoustie, Scotland
    Well that is not my experience, I have seen quite a lot of broken welds when steel rods have been used to join steel to 316 and when you look at the weld where it has cracked it is granular in structure.
     
  10. Richard.

    Richard. Member

    Messages:
    18,197
    Location:
    Cambridgeshire
    That's possibly down to the fact that the joint was lower strength which it is .
    It's not a brittle joint hood.
    Ms is more ductile but lower strength.
     
  11. Hood

    Hood Forum Supporter

    Messages:
    9,634
    Location:
    Carnoustie, Scotland

    Ok I see what you mean now.
     
  12. hotrodder Member

    Messages:
    4,587
    SE England
    It's dilution between the two different metals (relative carbon, chromium & nickel content etc) that can result in a brittle weld microstructure... http://www.kobelco-welding.jp/education-center/abc/ABC_1999-02.html Dissimilar filler alloys like 309 are 'overalloyed' to fix the problems caused by dilution
    Cracks in metals virtually always look granular because metals have a crystalline structure. Exceptions like with beach marks in fatigue failure still have a granular region where the final fracture occured

    As said not a big deal with a fuel filler neck or rubber hung exhaust
     
  13. Richard.

    Richard. Member

    Messages:
    18,197
    Location:
    Cambridgeshire
    Fair do's I didn't think the joint was more brittle by using ms consumable on SS.
    I stand corrected.
     
  14. Daveville30

    Daveville30 Member

    Messages:
    108
    Location:
    Ireland
    Weld it up with dissimilar rods think there 29/9s.I've welded loads off stainless back box's onto mild steel ones with no problems.
     
Advertisements