The different between ASTM A105 and A105N
ASTM A105N where the ‘N’ stands for normalized.
It has been heat treated to A105N where the ‘N’ stands for normalized
It has been heat treated to remove the internal stresses caused by casting, forming etc.
If a customer specifically asks for A105N then it will be for a good reason. The normalizing heat treatment will ensure the A105N has superior properties to that of the A105.
The ‘N’ is not a category code, the A105 should be normalized if intended for use below -1 degree C.