In a message dated 2/27/01 5:30:26 PM Central Standard Time,
landspeedracer@email.msn.com writes:
<< Drivers are also questioning NASCAR's decision last year to increase the
strength of the front-end roll bars from 93-hundredths to 125-hundredths
steel. The stronger front-end bars could make the car less crushable. And
there are complaints about crews being allowed to use chrome-moly alloy in
the rollbars; that makes for stronger bars, but chrome-moly doesn't bend as
easily as other steel and can actually fracture. Plus if welding isn't done
just right, the welds can crystallize, crews say."
>>
John we have been doing a lot of chrome-moly welding at work and the problem
isn't the welding as it welds a lot like carbon steel but the stress
relieving after welding. The welds are wrapped up in blankets and heated with
induction type coils that are monitored very close. It takes about 4 hours to
stress relieve each weld. It is a controlled temp and gradually increases to
about 1,100 degrees then held there a certain amount of time then a gradually
descend. This is pipe that is 24 inch in dia.so I would guess smaller sizes
would be different. If I was going to use chrom-moly at home (which I
wouldn't) you would need to preheat with a torch and wrap the weld with a
fire proof blanket and let cool slow. Just what I have seen. Larry Mac
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