Discussion of Time of Ultrasonic Examination for Low Alloy Steel Forgings of Reactor Pressure Vessels

To determine the most appropriate stage of ultrasonic test for reactor pressure vessels（RPV） steel forgings, this paper confirmed that RCC-M requires the ultrasonic test be done after final finishing, and analyzed the rationality of the requirement based on the ultrasonic examination mechanism, referring to other norms. It is proposed that a more appropriate stage of ultrasonic examination would be after the heat treatment for mechanical properties and before final finishing.