Production process of gear hub blank
Electric furnace smelting → die casting → forging → annealing → peeling → ultrasonic nondestructive testing → blank products. The ultrasonic flaw echo was found in the finished steel before machining the gear hub.
Defect detection method
Firstly, the position of the discontinuity in the longitudinal and transverse direction is determined for the blank steel with flaw detection discontinuity, and the equivalent size is calculated. Then, according to the position determined by the flaw detection, two pieces of samples are positioned and sampled; Secondly, macroscopic macrostructure observation was carried out on two pieces of steel samples to determine the specific parts and properties of the defects. Transverse and longitudinal metallographic samples were cut from the defect parts. After grinding, polishing and corrosion of the samples, the micro morphology of defects, non-metallic inclusions and microstructure were observed under the metallographic microscope; Finally, the blue fracture method was used to make the fracture surface, and the fracture analysis and SEM scanning were carried out.