Effects of Vacuum Carbon Deoxidation, Extra Low Sulfur Content, and ESR Process on the Quality of Cr-Mo-V Rotors

Abstract

In order to improve the quality of the central axial part of CrMoV steel rotors, the investigations were performed on the rotors made of conventional Si-killed steel, extra low sulfur Si-killed steel, vacuum carbon deoxidized (VCD) steel, and electroslag remelted (ESR) steel.
From the comparison of sulfur prints of the end cross sections of the rotors, an inprovement in the segregation pattern was observed in the rotor made by applying VCD and the reduction of segregates was found in the rotor made of extra low sulfur steel.
The rotor manufactured from ESR ingot showed the best result; in addition to finding no spot in sulfur print, there was no indication in the magnetic particle test of the axial bore in the magnetizing condition of 700 ampers per inch of the bore diameter. Some indications were detected, however, in the condition of 300 amperes per inch on the rotor made of Si-killed steel.
These results have been discussed in the light of the current concepts on segregation.