Posted by Sherman in Idaho [72.47.153.28] on Friday, May 09, 2014 at 15:58:29 :
In Reply to: Re: Brazing posted by gmharris [72.219.148.98] on Friday, May 09, 2014 at 13:55:45 :
I've not had a problem just letting them cool in still air, but on large or complex pieces some recommend burying it in vermiculite to let it cool even slower. I did once wrap a manifold up in some old fiberglass insulation but I don't know if it was necessary.
When welding cast iron, the best is to heat the whole piece red hot and work on it that way, then put it back in the oven to cool. Obviously most shops can't do that. I saw pictures once of someone welding a crack in a big Caterpillar gear case, probably at least 6 feet by 3 feet. The brought it out of the furnace bright red, and a welder in a reflective foundry suit welded it, then they put it back in the furnace to cool for at least 24 hours.
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