Final answer:
The endurance limit of AISI 1020 CD steel under rotating conditions depends on its tensile strength.
Step-by-step explanation:
The endurance limit of AISI 1020 CD steel refers to the maximum stress that the steel can withstand without undergoing fatigue failure under rotating conditions. The endurance limit depends on various factors such as the surface condition, loading conditions, and the presence of notches or stress concentrations. Typically, for AISI 1020 CD steel, the endurance limit under rotating conditions is around 50% of its tensile strength. Therefore, to determine the endurance limit, we need to know the tensile strength of the steel.