Process and apparatus for treating ingots

Claim 1

IN THE PROCESS OF IMPROVING THE SURFACES OF A CYLINDRICAL METAL INGOT OF A REFRACTORY AND EXTREMELY REACTIVE METAL FROM THE GROUP CONSISTING OF TITANIUM, ZIRCONIUM, URANIUM, HAFNIUM, AND MOLYBDENUM AND BASE ALLOYS THEREOR, THE INGOT BEING OF SUBSTANTIALLY CIRCULAR CROSS SECTION, THE STEPS COMPRISING MOUNTING THE INGOT IN A HERMETIC ENCLOSURE WITH THE INGOT AXIS BEING HORIZONTAL FOR ROTATIONAL MOVEMENT, COMPLETELY SURROUNDING THE INGOT WITH AN INERT GASEOUS ATMOSPHERE AT SUBATMOSPHERIC PRESSURE, PLACING A NON-CONSUMABLE ELECTRODE AT A POINT ADJACENT ONE EDGE OF THE INGOT AT A POINT VERTICALLY ABOVE THE AXIS AT AN UPPER HORIZONTAL PORTION OF THE CYLINDRICAL SURFACE OF THE INGOT, PASSING AN ELECTRICAL CURRENT OF FROM ABOUT 100 TO 300 AMPERES BETWEEN THE ELECTRODE AND THE INGOT TO ARC MELT THE SURFACE OF THE INGOT AT THAT POINT TO PRODUCE A POOL OF MOLTEN METAL TO A DEPTH OF APPROXIMATELY 1/4 INCH, AND ROTATING THE INGOT AT A SURFACE SPEED OF 3 TO 12 INCHES PER MINUTE SO THAT ARC WILL MELT SUCCESSIVE PORTIONS OF THE SURFACE, AND SIMULTANEOUSLY WITH SAID ROTATION, SLOWLY MOVING THE INGOT ALONG ITS HORIZONTAL AXIS SO THAT THE PATH OF THE MOLTEN POOL WILL FORM A HELICAL SPIRAL ALONG THE CYLINDRICAL SURFACE OF THE METAL INGOT, THE TURNS OF THE SPIRAL OVERLAPPING SLIGHTLY WHEREBY THE ENTIRE CYLINDRICAL SURFACE OF THE INGOT IS SO MELTED THEREBY ELIMINATING THE ROUGHNESS POROSITY, GAS-POCKETS AND OTHER FLAWS FROM THE TREATED SURFACES AND MAINTAINING THE INERT GASEOUS ATMOSPHERE ABOUT THE INGOT UNTIL THE TEMPERATURE OF THE SURFACE OF BELOW THAT AT WHICH THE METAL IS REACTIVE WITH THE ATMOSPHERE.