PISTON PIN Russian patent published in 2011 - IPC F16J1/16 

FIELD: machine building.

SUBSTANCE: invention refers to piston pin and is designed for pivot connection of piston with upper head of connecting rod in internal combustion engine. The piston pin is made out of heat treated carbon steel of decreased hardenability, with contents of carbon from 0.40 to 0.85 wt %, possessing ideal critical diameter, characterising its hardenability, equal to 0.8-1.2 of its wall thickness. The piston pin consists of external cylinder surface and internal cylinder surface forming its wall, said surfaces are restricted with circular flat ends from both sides. The wall of the pin consists of a core and of a hardened layer on external cylinder surface of the core. The hardened layer is elongated to both ends at least at length of not less, than half of wall thickness. Depth of hardened layers of the piston pin is 0.12-0.24 of its wall thickness. Microstructure of hardened layers 4 consists of tempered martensite of 55…63 HRC hardness and consists of source austenite with dimension of actual grain 11-14 points. The core of the piston pin wall has microstructure in form of troostite or troosto-sorbite or sorbite of 30…50 HRC hardness.

EFFECT: increased fatigue life of piston pin.