Process of preparing a ferrous alloytype powder for powder metallurgy and of preparing high strength articles therefrom

Claim 1

THE PROCESS OF PREPARING A POWDERED METAL PRODUCT FOR USE POWDER METALLURGY FROM A SOLID STARTING MATERIAL CONSISTING ESSENTIALLY OF (1) IRON, PREDOMINATLY IN THE FORM OF ADDITIVE IRON, AND CONTINING NOT OVER ABOUT 1% OF IMPURITIES SELECTED FROM THE GROUP CONSISTING OF THE OXIDES OF ALUMINUM, SILICON, TITANIUM, CHROMIUM CALCIUM AND MAGNESIUM, (2) METALLIC MANGANESE, WHICH IS PRESENT IN THE AMOUNT OF ABOUT 0.1% TO ABOUT 1%, (3) MOLYBDENUM IN THE FORM OF AT LEAST ONE HYDROGENREDUCIBLE COMPOUND THEREOF SELECTED FROM THE GROUP CONSISTING OF THE OXIDES AND CHLORIDES OD MOLYBDENUM, AND WHICH IS PRESENT IN THE AMOUNT OF ABOUT 0.1% TO ABOUT 1%, AND (4) NICKEL IN A FORM SELECTED FROM THE GROUP CONSISTING OF (A) METALLIC MICKEL AND (B) THE HYDROGENREDUCIBLE COMPOUNDS THEREOF WHICH ARE SELECTED FROM THE GROUP CONSISTING OF THE OXIDES AND CHLORIDES OF NICKEL, AND WHICH IS PRESENT IN THE AMOUNT OF ABOUT 1/2% TO ABOUT 21/2%, ALL PERCENTAGES GIVEN BEING BASED UPON THE WEIGHT OF THE FINAL PRODUCT AND ALL EXCEPT THAT OF THE IRON IMPURITIES BEING BASED ON THE RESPECTIVE METALS AS SUCH; SAID PROCESS COMPRISING THE STEPS OF BLENDING TOGETHER THE NAMED MATERIALS IN SOLID, FINE-PARTICLE FORM TO PROVIDE A STARTING MIXTURE, REDUCING THE HYDROGEN-REDUCIBLE INGREDIENTS OF SAID STARTING MIXTURE BY CONTACTING SAID STARTING MIXTURE WHILE IN A REDUCING ZONE WITH A NONOXIDIZING GAS CONTAINING A SUBSTANTIAL PROPORTION OF HYDROGEN AND WHILE MAINTAINING THE TEMPERATURE OF ALL THE MATERIALS IN SAID REDUCING ZONE IN THE RANGE OF ABOUT 1200*F. TO ABOUT 1600*F. FOR A TIME SUFFICIENT TO EFFECT THE REDUCTION OF SUBSTANTIALLY ALL THE HYDROGEN-REDUCIBLE MATERIAL PRESENT; AND COOLING THE REMAINING SOLID MATERIAL, FOLLOWING THE REDUCTION AFORESAID, UNDER NON-OXIDIZING CONDITIONS AND TO A TEMPERATURE SUCH THAT IT MAY BE EXPOSED TO THE ATMOSPHERE WITHOUT SUBSTANTIAL SPONTANEOUS OXIDIATION, THE POWDERED METAL THUS FORMED BEING CAPABLE OF FORMATION BY CONVENTIONAL POWDER METALLURGY PRACTICES INTO ARTICLES HAVING HIGH TENSILE STRENGTH AND LOW SHRINKAGE CHARACTERISTICS.