Compare AISI 1018 and AISI 1045

[aws19]

I am making a part for lifting a small weight of equipment by means of an api thread machined on the lifting part to mate with the lifted part. the drawing calls for AISI 1018. Due to availability I want to use AISI 1045.
the weight might be a ton. The thread is api regular 3.3" dia, 5 tpi w/ 3" per foot taper.
What could be the eventual problems resulting from this substitution?

 

[TVP]

The 1045 steel will be stronger than 1018 if they are processed similarly (cold drawn bars of the same diameter). The higher strength means that the ductility and fracture toughness will be lower. If the load application rate is very fast (dynamic) or at very low temperatures, then 1045 may perform worse than 1018. Otherwise it will probably outperform 1018.