TIG welding Cast steel to 304SS

admin

I've got a project going on where I'm taking a stock exhaust manifold off my car, cutting it up and welding a 304ss flange to it. We will be using a Miler synchrowave 180amp welder. I'm just wondering what rod to use, does it need to be a Ni, 309, 316, what kind? The cast steel is definitely got a lot of nickel in it so I'm thinking a nickle rod. The part will not be experiencing much stress, just a lot of heat/cooling. I to a piece of the cast steel and cut it, and welded the two pieces of cast back together with a regular MIG welder with mild steel wire. It welded phenomenally, took a hammer to it after it cooled and beat the **** out of it. The piece didn't crack at all, not even the slightest.
Reply:I might add when I welded the two pieces of cast steel together; there was no preheat. Once welded I didn't speed up or slow down the cooling process.
Reply:309L for carbon to 304.
Reply:^ the cast steel is a low carbon material? I need to know so I can order my welding rods tomorrow just incase they don't stock them. I know they stock the 309/309l rod but not nickel rod.
Reply:I don't see why it would have a particularly high carbon content.  Whether it does or not, you can still use 309L.  The whole point of using it with carbon steel is that the alloy content is sufficiently high and carbon content low enough to prevent martensite formation/cracking when diluted.  If you want, you can throw a 200 degree preheat on the manifold, butter the manifold with the 309L, and then weld it to your flange.
Reply:Ok so a 309L welding rod for the Cast steel to 304SS and a 309 for mild steel to 304SS? Correct? My plan was to weld it and then throw some flame retardent rags around the weld spot to prolong the cool down process, since i don't have sand or kitty litter to cover it up.
Reply:Don't bother with any 309 filler at all.  For all low carbon/mild/low alloy steel to austenitic stainless, use 309L.  I would use 309L for joining 309 to 309 and for joining dissimilar stainless steels as well, excluding those with the higher molybdenum content like 316.