The plan of 17-4PH steel valve seat is shown in the figure. The routine processing procedure shall be blank forging solution treatment, rough processing, aging treatment and finishing. In order to reduce manufacturing costs, aging treatment can be carried out before rough machining, that is, solution and aging treatment are carried out continuously, and rough machining and finish machining are carried out continuously. The workpiece is processed by the rough machining and finishing process of billet forging solution treatment and aging treatment. The processing sequence is ① rough turning the internal and external dimensions, and 2mm allowance is reserved at the R162mm ball. ② Finish turning to complete the size of each part, and the ball R162mm leaves grinding allowance. ③ Rough grinding and fine grinding complete R162mm ball size processing.

If the measured electrode contact resistance value increases than before, it means that the electrode surface is covered by insulation layer or partially covered; If the resistance value is lower than the previous value, it means that conductive deposition layer is attached to the electrode and lining surface.