Yes, it is possible to crack a cast iron pan by subjecting it to extreme temperature changes, such as rapidly heating it and then suddenly cooling it. Cast iron is a brittle material, and drastic thermal shocks can cause it to fracture or crack.
When a cast iron pan is heated, it expands due to the increased molecular activity within the material. Rapidly cooling the pan by submerging it in ice-cold water causes the metal to contract quickly, leading to differential expansion and contraction across the pan's surface. This rapid change in size and shape can create internal stress within the material, which may exceed its strength and result in cracking.
To avoid this, it is generally recommended to heat and cool cast iron pans gradually and evenly to minimize the risk of thermal shock. Slowly preheating the pan, allowing it to heat evenly, and cooling it gradually after use are good practices to preserve the integrity of the cast iron.