The piston passes the gas pressure through the connecting rod to the crankshaft to realize the transformation of the heat energy to the mechanical energy, and the piston is contacted with the high temperature, high pressure and strong corrosive gas, so that the utility model has the advantages of sufficient strength and hardness, Good heat resistance and thermal conductivity, high fatigue strength and corrosion resistance In order to reduce the reciprocating inertia force. The piston of a large marine low-speed diesel engine is usually a crosshead type The heat treatment process by normalizing and annealing, and iron pearlite are ferrite organization, has good heat resistance. Piston alloy quenched and tempered steel has better heat resistance and corrosion resistance. The skirt with nodular cast iron annealing treatment, with good wear resistance…