Abstract: The method effects a tight fit of a ferrous ring reinforcement at the head end of an aluminum alloy piston which tight fit remains during use of the piston. The procedural steps of the preferred method include: providing an aluminum alloy piston slug with an annular shoulder adjacent its head end; solution heat treating the aluminum alloy slug for one hour minimum at a temperature within the range of from 483.degree. C. to 510.degree. C. (900.degree. F. to 950.degree. F.); rapidly cooling the solution heat-treated aluminum alloy slug to create a super-saturated aluminum alloy solid solution; preheating the ferrous ring to approximately 538.degree. C. (1000.degree. F.), a temperature above the head end temperature during use of the piston, to expand the ring temporarily; preheating the aluminum alloy slug to a working temperature of approximately 204.degree. C. (400.degree. F.