Cemented carbide with binder phase enriched surface zone and enhanced edge toughness behavior and process for making same
AssigneeSandvik AB
InventorsAke Ostlund, Ulf Oskarsson, Per Gustafson, Leif Akesson
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Abstract
Cemented carbide inserts are available containing WC and cubic phases of carbide and/or carbonitride in a binder phase based on cobalt and/or nickel with a binder phase enriched surface zone. The binder phase content along a line essentially bisecting the rounded edge surfaces increases toward the edge and cubic phase is present. As a result, the edge toughness of the cutting inserts is improved.
Claims16
A coated cemented carbide insert with rounded edge surfaces with improved edge toughness containing WC and cubic phases based on a metal carbide and/or carbonitride in a binder phase based on cobalt and/or nickel with a binder phase enriched surface zone essentially free of cubic phase wherein the binder phase content along a line essentially bisecting a rounded edge surface is greater near the edge than the nominal content of binder in the insert as a whole, decreases away from the edge, cubic phase is present along said line and the binder phase content in the outermost 25 .mu.m thick surface zone is >1 of the binder phase content in the inner of the insert.
A method of making a coated cemented carbide insert with improved edge toughness containing WC and cubic phases of a metal carbide and/or carbonitride in a binder phase based on cobalt and/or nickel with a binder phase enriched surface zone comprising said cemented carbide and thermally treating said sintered body, said treatment being started with a short nucleation treatment at increased nitrogen pressure, 300-1000 mbar, at a temperature between 1280.degree. C. and 1450.degree. C. carded out for <5 minutes followed by a period at a lower nitrogen pressure of 50-300 mbar for 10-100 min whereafter the nitrogen gas is maintained to a temperature where the binder phase solidifies at 1265.degree. C.-1300.degree. C.
Dependencies are inferred from the claim text.