Abstract: A method of embrittling cleaned steel particles is described, followed by a grinding and sorting operation. Depending on the initial carbon content of the steel scrap, a reducing and carbon-containing atmosphere may be provided to carburize the particles as they are being embrittled. A quenching operation is provided at the end of the process to embrittle the particles and before the particles are ground. The ground grit which is produced may then be sorted by size and used as an abrasive compound, or, alternatively may be further ground and annealed in a subsequent operation to provide suitable powder for forming sintered parts. Prior to annealing the grit may be further ground in a partial oxidizing atmosphere to preoxidize the powder, in order to provide oxygen directly within the powder to react with any residual carbon so that the carbon monoxide gas can be formed and the powder can be substantially free of both carbon and oxides when the reaction is complete.

Abstract: A method and apparatus 10 are disclosed for annealing metal powder so at to decrease the carbon content of the powder while also reducing the oxygen content thereof.

Abstract: A method is disclosed of converting tangled ribbons of ductile machining scrap into a densified intermediate product useful for making metal powder. A collection of the scrap having a packing density less than 50 lbs/ft.sup.3 is subjected to impacting forces between weighted, freely moving elements and an anvil means for progressively flattening the scrap. The impacting is repeated to substantially flatten all of the scrap and reduce some of the ribbons by fatigue breakage to chips; the resulting processed scrap will have a packing density in excess of 90 lbs/ft.sup.3.

Abstract: Methods are disclosed for embrittling scrap metal for comminution and for subsequent or simultaneous treatment of the comminuted metal powder to improve sintering kinetics and prevent oxidation of alloying ingredients. A first embrittling method impacts the scrap metal at a temperature below its ductile-brittle transition temperature to cryogenically provide scrap metal powder. The scrap metal is subjected to two impacting operations (such as by use of a ball milling machine), the first operation being carried out simultaneously with the cryogenic medium and the second impacting operation is carried out at ambient temperature conditions utilizing milling elements which impart cold work to at least a portion of the cryogenic powder. An anti-oxidation agent, such as copper or iron, is mechanically transferred to substantially each particle of said cryogenic powder during the second operation to form a continuous copper or iron envelope thereabout.

Abstract: A mechanical mixture of selected powders is subjected to compressive forces to define a pre-compact, the pre-compact then being subjected to liquid phase sintering for producing a raw alloy steel product which is more economical and has enhanced physical properties, particularly tensile strength as compared to sintered compacts produced by the prior art to date. The improvement in physical properties and processing technique results principally from the use of a mechanical mixture consisting of a base iron powder and a coated alloyed additive powder having selected alloying ingredients (such as manganese, nickel, molybdenum, in an iron-carbon system); the particles of the alloyed powder have a thin flash coating of a low melting metal, such as copper, to control carbon diffusion into the base iron powder during liquid phase sintering.

Abstract: A method is disclosed of making sintered parts with cryogenically-produced powder derived from scrap metal, such as machine turnings. The scrap metal is subjected to two impacting operations (such as by use of a ball milling machine). The first operation is carried out with the use of a refrigerating agent (to lower the temperature of the scrap metal below its ductile-brittle transition temperature) thereby resulting in comminution of the scrap to a cryogenic powder. The second impacting operation is carried out at ambient temperature conditions utilizing milling elements which impart cold work to at least a portion of the cryogenic powder; simultaneously, copper is mechanically transferred to substantially each particle of said cryogenic powder to form a continuous copper envelope thereabout. The coated cryogenic powder is then compacted and sintered; the sintered product may be subjected to hardening or tempering treatments if desired.

Abstract: A mechanical mixture of selected powders is subjected to compressive forces to define a pre-compact, the pre-compact then being subjected to liquid phase sintering for producing a raw alloy steel product which is more economical and has enhanced physical properties, particularly tensile strength as compared to sintered compacts produced by the prior art to date. The improvement in physical properties and processing technique results principally from the use of a mechanical mixture consisting of a base iron powder and a coated alloyed additive powder having selected alloying ingredients (such as manganese, nickel, molybdenum, in an iron-carbon system); the particles of the alloyed powder have a thin flash coating of a low melting metal, such as copper, to control carbon diffusion into the base iron powder during liquid phase sintering.

Abstract: A mechanical mixture of selected powders is subjected to compressive forces to define a pre-compact, the pre-compact then being subjected to liquid phase sintering for producing a raw alloy steel product which is more economical and has enhanced physical properties, particularly tensile strength as compared to sintered compacts produced by the prior art to date. The improvement in physical properties and processing technique results principally from the use of a mechanical mixture consisting of a base iron powder and a coated alloyed additive powder having selected alloying ingredients (such as manganese, nickel, molybdenum, in an iron-carbon system); the particles of the alloyed powder have a thin flash coating of a low melting metal, such as copper, to control carbon diffusion into the base iron powder during liquid phase sintering.