Process for hardening the aluminum alloy portion of an aluminum alloysteel bearing

Claim 1

A PROCESS FOR INPROVING THE FATIGUE RESISTANCE AND HARDNESS OF THE ALUMINUL ALLOY PORTION OF AN ALUMINUM ALLOY-STEEL BEARING COMPRISING THE STEPS OF: (A) COEXTENSIVELY METALLURIGICALLY BONDING AN ALUMINUM ALLOY WHICH INCLUDES SILICON IN QUANTITIES OF FROM ABOUT 2.5% TO 11.6% BY WEIGHT TO A STEEL SUPPORT, (B) FORMING THE RESULTING BEARING TO THE DESIRED SHAPE, (C) MACHINING THE ALUMINUM ALLOY SURFACE OF THE BEARING TO THE DESIRED THICKNESS, (D) HEATING THE BEARING TO A TEMPERATURE OF AT LEAST 750*F. BUT NOT IN EXCESS OF ABOUT 10*F. BELOW THE EUTECTIC MELTING POINT OF THE ALUMINUM ALLOY, (E) MAINTAINING THE BEARING AT SAID TEMPERATURE FOR A PERIOD OF AT LEAST FIVE MINUTES TO CAUSE AT LEAST A PORTION OF THE SILICON IN THE ALUMINUM ALLOY TO GO INTO SOLUTION THE LENGTH OF SAID PERIOD BEING INSUFFICIENT TO CAUSE THE FORMATION OF ANY SUBSTANTIAL QUANTITY OF BRITTLE IRON-ALUMINUM ALLOY AT THE INTERFACE BETWEEN THE ALUMINUM ALLOY AND THE STEEL, AND (F) BEFORE THE TEMPERATURE OF THE BEARING HAS COOLED IN EXCESS OF ABOUT 15*F., QUENCHING THE BEARING IN A FLUID MAINTAINED AT ABOUT ROOM TEMPERATURE FOR CAUSING THE SILICON IN THE ALUMINUM ALLOY TO PRECIPITATE IN THE FORM OF SUB-MICROSCOPIC PARTICLES DISPERSED UNIFORMLY WITHIN SAID ALUMINUM ALLOY, WHEREBY THE FATIGUE RESISTANCE AND HARDNESS OF THE BEARING IS SUBSTANTIALLY INCREASED.