I have a hotside I want to weld a flange. Never did one before. Do you guys pre/post heat them or just go all out? It's going to be a stainless flange.

If I do this blindly I'm going to use supermissle/312L.

What would you guys do?

 

312L should work fine. just need to clean the crap out of the turbine housing as it is cast, and yes, I would def. pre heat...I typically heat it in the oven for a bit, then do a root pass, then throw it back in the oven when it has cooled some, then take it back out and do a filler pass, and repeat if more passes are needed...when the last pass has been achieved, put it back into the oven, but gradually dial back the temps over the course of an hour or so, so it doesn't cool too quickly, otherwise it will surely crack

 

I welded a mild steel flange on a cast turbo exhaust housing for my brother years ago. I used a nickel rod and an arc welder. I heated the housing for 1 1/2 hours @250* made a root pass, reheated, made final pass. When the turbo went bad I beat the hell out of the flange with a hammer trying to break my weld and it wasn't happening. I also repaired a sbc starter mounting tab the same way.

 

I welded a gate provision onto my turbine housing. I preheated it with a MAP torch till it blued then ran two passes with 308 rod over it. It's holding up great and offers unparalleled boost control in addition to looking gangster.