早期转子心部的冶金质量很差，容易发生低应力脆断，因此，早期的转子多为有中心孔转子。当今的冶金技术提高了转子钢的纯度，可以保证转子心部无超标缺陷，转子从表面到心部各项韧性指标差距减小，提高了转子的性能均匀性，特别是大大地改善了转子钢的断裂韧性，表明当今转子锻件的冶金质量有了显著改善，为实心转子的应用提供了较好的依据。

Most of the earlier rotors were rotors with center holes due to their bad metallurgy quality at the core, easily causing fracture with low stress. The present metallurgy technology improves the purity of rotor steel to ensure the core of rotor without defects exceeding standard. The gap of all toughness indicators from the surface to the core became less, improving the property eveness of rotor, especially fracture toughness of rotor steel. It shows that the metallurgy quality of the present rotor forging has been improved greatly, providing good evidence for application of solid rotors.