nalysis of unqualified causes of generator yoke Q345C heavy and wide plate
ZHANG Xueling 1,LI Maolin 2
1.NCS Testing Technology Co.,Ltd., Beijing 100081，China；2. Nuclear and Radiation Safety Center，
Ministry of Ecology and Environment of the People′s Republic of China，Beijing 100082，China
Abstract：The phenomenon of unqualified ultrasonic flaw detection results of generator yoke Q345C heavy and wide plate was studied. The tensile testing machine, impact testing machine, metallographic microscope, scanning electron microscopy and energy dispersive spectrometer were employed for the comprehensive analysis including the tensile properties, impact performance, macroscopic morphology, inclusion, microstructure, macrographic morphology and spectral analysis. The causes for the unqualified ultrasonic flaw detection results of generator yoke Q345C heavy and wide plate were analyzed. The experimental results showed that it was due to a black defect zone at 23 mm from the lower surface of steel plate. The detected plane domain of defects was Ushaped. The defect width exceeded 70 mm. The main defects were oxide inclusions, holes and center porosity. In order to improve the qualification rate of ultrasonic inspection of generator yoke Q345C heavy and wide plate, all aspects of steelmaking should be strictly controlled to strengthen the steel refining, improve the purity of molten steel, reduce the oxygen content in molten steel, and control the content and morphology of inclusions in steel to improve the internal quality of billets.
2022, Vol. 40 
