Choosing cast iron (not costly iron actually) or carbon steel for fabricating bearing house is not always the matter of strenth and damping effect as I knew.
Since most of the bearing housings are very complex in features & shape and also cast iron is very good material to cast something that has very difficult and complex shape and features, and cast iron have exellent castability, it is widely selected.
If you have heavy radial and thrust load along the shaft, then carbon steel is oftenly selected. If you do not have heavy loads, then cast iron is mostly selected.
you do not have to have any bias on cast iron by this explanation.
it is cheap and nice also. that's why it is widely selected for bearing housing material. thing is like this. the more than you need is not value adding. most of cases, cast iron is very much sufficient,.