I had to angle grind a crank arm from a square taper BB as the previous careful owner had stripped the thread.There is something so satisfying in cutting into cast aluminium with an angle grinder, like a knife through butter.
Bit late spotting this, grinding wheels/discs and aluminium are a bad mix. Please dump the disc you used before attacking other items, a face full of hot metal and disc are not pleasant and are bad for the complexion.
But is like a firework display I must admit, try titanium and duralamin for different colours.