Which is stronger solid steel rod or hollow steel pipe?
Believe it or not, a hollow steel pipe is generally stronger than a solid steel rod, at least for two shafts of the same length and the same an equal weight of steel. Variations in length and type of steel will of course have an impact on the strength of the rod/pipe.
This is primarily due to the fact that most of the strength of a cylinder comes from its outer portion; hence even though it is hollow in the center it still has its strength. This results in a better strength to weight ratio for a hollow pipe than a solid rod. It also make the hollow pipe better apt to take more weight and is less likely to bend under that weight. A hollow steep pipe is also less likely to buckle in axial compression.