Process for the manufacture of piston rings

Claim 1

THE PROCESS OF MAKING ALLOYED CAST PISTON RINGS WHICH ARE SUBSTANTIALLY FREE OF PRIMARY CEMENTITE AND STACK MOLDING IN A GREEN SAND MOLD THE PISTON RINGS OF A CAST IRON HAVING THE COMPOSITION 3.00-4.00% CARBON 1.50-3.10%SILICON,0.6-15% MANGANESE, 0.8-2.0%COPPER, 0.05-0.70% PHHOSPHOURS,2.02-0.15% SULPHUR,AND THE BALANCE SUBSTANTAILLY ALL IRON WHEREBY THE CAST PISTON RING HAVE A WHITE STRUCTURE HEATING TO A TEMPERATURE SLIGHTLY ABOVE THAT OF THE EUTECTOID TANSFORMATION POINT SO THAT AUSTENITIZATION TAKES PLACE AND FOR A TIME SUFFICIENT FOR ALL THE CARBON TO BE DISSOLVED QUENCHING WHILE MAINTAINING A SUBSTANSTIALLY MARTENSITIC STRUCTURE AGAIN HEATING AT A CONSTANT TEMPERATURE BETWEEN 420*C.AND 550*C. FOR A PERIOD OF THE ORDER OF THREE HOUR TO BRING FORTH GRAPHITE NUCLEATION INCREASING THE TEMPERATURE AFTER SAID NUCLEATION HEATING TO A TEMPERATURE TURE HIGHER THAN THE EUTECTOID TRANSFORMATION POINT FOR A PERIOD OF TIME SUFFICENT TO GRAPHITZE THE CARBON IN THE PRIMARY CEMENTITE COOLING AT A CONTROLLED RATE SAID COOLING RATE BEING TEMPERING AT A PREDETERMINED TEMPERATURE TO INSURE A PREDETERMINED HARDNESS.