Tough Spindles!!!!!

[BlasterMod6]

What metal are atv spindles made out of? Specifically the 89 warrior spindles? Just drilled a hole thru the upper ball joint hole side to put a bolt thru the spindle to hold to the ball joint stud because its a warrior to blaster brake mod. While I was in the process of doing this I broke 3 drill bits and melted 3 tips to beyond hell. Finally got it done with a carbide cutter on a dremel. Just wondering what type of metal these f*^&ing spindles are made out of so I can go get a drill bit for that metal. THings are a pain in the ass but a much needed upgrade from the stock blaster front brakes that werent maintained by the previous owner.