Welding process of semi martensitic stainless steel pneumatic ball valve seat Forging At forging temperature, 17-4PH steel has poor plasticity, large deformation resistance and is prone to cracks. Forging temperature shall be strictly controlled. The initial forging temperature is 1180 ℃, and the final forging temperature is 1010 ℃. Blank heating 3~3 After 5h, the temperature reached 1230 ℃, and the first heat forging was carried out after discharging, no abnormality was found. The second heat forging was carried out after 0.5 h of reheating, and no abnormality was found. Level at 900~950 ℃ to prevent flash cracks. In addition, a punch shall be used in the forging process, and the punch shall have a certain taper. In order to increase the reaming effect, several punches can be used together.

5. What is calibration? What is the basis for calibration? Under specified conditions, a set of operations used to determine the value indicated by the measuring instrument or measuring system or the quantity represented by the physical measurement, and the corresponding set of operations reproduced by the standard are called calibration. Calibration is based on calibration specifications or calibration methods, which should be generally specified uniformly, and can be formulated by oneself under special circumstances.