Chainsaw Repair

One day in a shop someone bought a new 36" Tsumura bar from us but wanted a 1/2" hole drilled in it to attach an accessory,the person was waiting so I quickly tried to drill the hole in it but no luck,a normal new drill bit would not drill it,I got a carbide bit and tried again,no luck. Finally I heated the spot red hot with a torch and smoked the bit thru. Any other bar I've drilled easily.
Tsumura does say to avoid twisting the bar badly or bending it hard,it can crack.(From the hardness)