Quote:
Originally Posted by oldsinner111
I know from my machining days,you can work harden metal to a point you need ceramic inserts to turn the metal.
Is it the same for welding? I have welded and welded for 6 years on my muffler,and I'm about to wrap the leak with fiberglass then resin,and put aluminum tape on top.
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If you are electric welding then the chance you get rapid cooling and a brittle weld is possible. Gas welding won't do this (so quickly) as the heat effected zone is more often than not much larger...
...but you are not necessarily hardening or fatiguing the metal by welding alone (unless you're in the habit of quenching the work piece for some unknown reason). If you were welding say cast iron you'd wrap the weld in blankets to slow the cooling - but for steel this isn't necessary.
On an exhaust - dirty - you are more likely to have gotten muck in your welds - this is more likely to be the cause of unwanted cracks and your repeated welding activity.
At some point or other - I'm sorry to burst the bubble (!) - but you just have to go and buy a new exhaust...