This tech tip comes from Brembo and can help explain why some rotors crack and fail where the hat meets the plates.
INCORRECT ASSEMBLY OF THE CALIPER BODY ON THE AXLE
Description: The braking surfaces has broken away from the rotor’s hub/hat. Asymmetrical braking surface wear can be noted: the central area of the external surface in respect of the vehicle and the outer edge of the internal surface. In this case mechanical stress has caused the disc to break and the braking surfaces have come away.
Consequences: The impact of this breakage can be felt while braking and a very loud rasping noises can be heard. Safety of the vehicle is compromised.
Advice: Before fitting new discs check the alignment and assembly of the caliper body on the axle or knuckle.