Why companies buy steel castings, iron castings and aluminum castings and forgings from China? Are the Chinese castings quality good?

They buy Chinese castings for variety of reasons. Some for reduction of cost, some for accessing world-class capabilities, and others for better focusing on its core resources. Are they happy to buy Chinese castings? Some of them are happy, while others are not. Why? For those who are happy, they get good prices and deliveries...