We have only had our Samsung slide in range for 2.5 years.  Used self-clean for the first time the day after Thanksgiving.   Suddenly have cracks running through the enamel on the bottom of the oven and a rust spot the size of a quarter.  From reading over 35 community forum comments regarding the same/similar issue, this is definitely not an isolated incidence but a defective Samsung product.  Had my GE range 23 years...no issues ever.