AISI 4140 thick to S355 thin...

  1. oliwb Member

    Well this is an interesting one....we've been asked to put a stand together for a customer to use at the upcoming offshore Europe exhibition. It involves welding some thick (~1" wall section) caps made from (what we're pretty sure is) 4140 quenched and tempered 80ksi to some very thin (2mm thick) S355 plate. It's basically a pipe to plate fillet weld where the pipe is going to be horizontal and have around 100kg hanging off it. We've welded 4140 before and have a WPS for it, but we can't really run it here because it'll be impossible to PWHT the joint. The stand doesn't need to be leak proof - just needs to support ~ 100kg of weight attached to these caps so there will be a bending moment on the weld. My question is - knowing how crack susceptible it will be to do this with ER80 (even if we pre-heat it), could we stick these together using a 309 or 312 wire to make a more reliable weld? The ultimate strength really isn't an issue but embrittlement and cracking could be.....Thoughts on a postcard please!
  2. TechnicAl

    TechnicAl Member

    309L will produce a crack free weld as the austenite will absorb any Hydrogen thus avoiding it passing to the 4140 and cracking it.

    312 will be stronger but with less austenite

    Id go for 309L
  3. oliwb Member

    Ace, thanks Al!