"过渡圆半径" can be translated as "radius of the transition fillet" or "radius of the transition round" in English.
"Transition fillet" is often used in mechanical engineering and manufacturing contexts to describe the rounded or curved section that connects two different surfaces or features, providing a smooth transition.
"Transition round" is a more straightforward and general term that also conveys the idea of a rounded or curved section for transition purposes.
Both expressions are acceptable, and the choice between them may depend on the specific context or industry preference.