Although this thread is done, I'd like to add some general advice, based on
decades of aircraft work.
We use 4130 chrome moly for most steel work. It's pretty forgiving, pretty
strong, and readily available in good quality, most commonly as seamless
tube and flat stock. Aircraft Spruce, Wicks, etc. all stock 4130. It welds
great with oxy-acetylene, and as has already been noted here, gas welding
tends to minimize stresses because of the slow heating and built-in
normalizing. However, to be sure it's always advisable to normalize after
the structure is done.
Good gas welding practice should produce decent fillets and after
normalizing, if there's a tendency to crack it's probably a design issue.
BTW - 4130 is typically welded with plain copper-coated mild steel rod, with
a slightly carburizing flame. If the welds look foamy and there's a great
amount of sparking while welding, you're probably oxidizing the weld.
Good luck !
Karl Vacek
> Once again the power of the list is incredible. Several helpful replies
have
> determined my course of action.
>
> 1. Better support of the weight of the turbo/carb weight with a bracket
> between the turbo and the block.
> 2. Normalize the piece after welding (heat to red heat and cool slowly) I
have
> access to a high temp oven that will do nicely
> 3. Thinnest gauge that will hold the pressure will behave best.
> 4. Produce neat, nicely radiused welds.
>
> Thanks guys, I'll let you know how it comes out in a week or two.
>
> Regards,
> Glen Byrns
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