First time welded cast iron, then found argon leaked

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I modified my toyota ct20b turbo housing with a 3 inch v-band, at the time didn't aware torch rear cap is leaking. In fact the leak made nickel rod sparkles difficult to weld and confused me(thought maybe a nickel or cast iron thing), but then I switched to 309L since it's less sensitive I proceeded even though the beads looking bit ugly... Now knowing that argon was contaminated I wonder is that critical, whether it'll hold under heat cycle?... (though I did weld full exterior/interior and then it survived a swear drop from 1 meter high without scratch)





This bead is after me more or less fixed the leak...


Reply:RikanBKKIt's evident: you are in full command - of whatever you are doing . . . carry on - and weld to destruction . . .Opus
Reply:My thinking, for what it's worth, would be...…….if the welded stuff doesn't pose a danger to the impeller, or any other moving parts, if it should come loose....I'd just go with it.  If that's the case...if something starts leaking again, you'd just have to reweld it properly next time.  Those welds might hold for 20yrs, who knows (shrug)
Reply:Thanks for input, in fact now the housing all welded up little I can do, just hopes for best.Lessons learned:1. Check back cap sealed is super important.2. Weld male v-band flange on turbo is dumb, should weld male part on pipe & female part on turbo, easier inspect warp/flatness
Reply:1. it's not cast iron, it's cast steel of some sort. This is a good thing, though. If it was cast iron it would crack off first time you used it. 2. Welding wastegates shut is always hit and miss... the extreme thermal cycling of a turbo will always crack that area eventually. As long as it doesn't come loose, that's the important thing.3. You need to weld that V-band on inside and out.... it WILL crack at some point otherwise. It might crack anyways. That's just what happens, all you can do is make it as mechanically strong as you possibly can. Most people make a backing plate to bolt to the turbo, and weld the V-band to the backing plate so you can be sure of full pen, full strength.
Reply:Munkul thanks for sharing those knowledge! Seems I confused cast steel / cast iron, indeed the sparks and surface all sorta like low carbon steelYou're absolutely correct about that wastegate, after remove from car found there was already a small crack, which I grinded then welded back with the plug. (and toyota seems used nickel alloy flapper arm for reason) I do preheated to 200℃ all around before welding & pumped 120amp I think I got good penetration, hope it could last 2 or 3 yr while I'm saving for new turbo lol
Reply:I doubt very much that that is cast steel. None the less it looks like you did a fair job of welding it.  I would just go with it.