PISTON AND METHOD OF MAKING A PISTON

摘要

A piston for an internal combustion engine is provided. The piston includes a pair of pin bosses formed of aluminum or an aluminum alloy spaced from one another in an axial direction. Each of the pin bosses has a generally circular opening for receiving a wrist pin. The pin bosses are formed integrally with surrounding areas of the piston, and each pin boss has a zone with increased hardness relative to the surrounding areas of the piston. The zone with increased hardness is at the inner periphery of the generally circular opening and resists deformation from forces between the piston and a wrist pin during operation of the internal combustion engine. Preferably, the zone with increased hardness has a dendritic microstructure with primary silicon crystallites dispersed throughout; are substantially free of pores and cracks; and have a Vickers Hardness Value of between 169 and 177.

主权项

1. A piston for an internal combustion engine, comprising:
a pair of pin bosses formed of aluminum or an aluminum alloy; said pin bosses being spaced from one another in an axial direction and each presenting a generally circular opening for receiving a wrist pin; and each of said pin bosses being formed integrally with surrounding areas of said piston body presenting a zone with increased hardness relative to said surrounding areas of said piston at an inner periphery of said generally circular opening for resisting deformation from forces between said piston and a wrist pin during operation of the internal combustion engine.