Working conditions: under bad conditions such as hightemperature, high pressure, high speed and badly lubricating. Piston touch withhigh temperature gas directly, constant temperature can achieve more than2500K, heated greatly with bad heat dissipation, so piston working temperatureis very high, with its top up to 600~700K and temperature is unevenlydistributed; top of piston withstands high gas pressure, especially for workingprocess, gasoline engine up to 3~5MPa, and diesel engine up to 6~9MPa, whichmake piston produce shocking and bear side thrust action; piston doesreciprocating action inside cylinder with high speed (8~12m/s), and its speedconstantly changes, which produce strong inertial force to make pistonwithstand additional load. Piston will be distorted, accelerate abrasion,produce additional load and thermal stress, and corroded chemically by gasunder this bad working condition.