Piston is one of the main moving parts of diesel engine. 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. The working condition of the piston is rather harsh, it is with a temperature of 1400-1800 DEG C, and the pressure. Up to 13MPa gas phase contact, resulting in a large thermal stress and alternating mechanical stress.
It is seriously corroded by the gas, and it has strong friction and impact with the cylinder wall under the condition of boundary lubrication. 1 times
The piston is exposed to high temperature, high pressure and strong corrosive gas, so it is required to have sufficient strength and hardness, Good heat resistance and thermal conductivity, high fatigue strength and corrosion resistance.
In order to reduce 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.