Constituent Part :Piston body, piston locking nut, piston rod, piston ring and rider ring.
High Strength Aluminum Alloy ,High Strength Cast Iron or 3Cr13etc. for piston body.
Copper Alloy ,38CrMoAlA,42CrMoE, 45# etc… for pinton locking nut.
20Cr13,38CrMoAlA,42CrMoE, High Frequency Quenching and Nitriding Treatment or spray WC on the surface to gain high rockwell hardness value for piston rod.