Method of making a fine grained cemented carbide

a cemented carbide, fine grain technology, applied in the direction of turning machines, turning apparatus, turning tools, etc., can solve the problems of limiting grain growth, unfavorable affecting toughness behavior, and particularly detrimental additions of vanadium or chromium, and achieve high deformation resistance and high toughness
US20050025657A1Inactive Publication Date: 2005-02-03SANDVIK INTELLECTUAL PROPERTY AB
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Patent Information

Authority / Receiving Office
US · United States
Patent Type
Applications(United States)
Current Assignee / Owner
SANDVIK INTELLECTUAL PROPERTY AB
Publication Date
2005-02-03
Estimated Expiration
Not applicable · inactive patent

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Abstract

According to the present invention there is provided a method of making a finegrained tungsten carbide—cobalt cemented carbide comprising mixing, milling according to standard practice followed by sintering. By introducing nitrogen at a pressure of more than 0.5 atm into the sintering atmosphere after dewaxing but before pore closure a grain refinement including reduced grain size and less abnormal grains can be obtained.
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Description

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a method of making a fine grained cemented carbide. By performing the sintering at least partly in a nitrogen-containing atmosphere, a grain refined cemented carbide structure has been obtained.

[0002] Cemented carbide inserts with a grain refined structure are today used to a great extent for machining of steel, stainless steels and heat resistant alloys in applications with high demands on both toughness and wear resistance. Another important application is in microdrills for the machining of printed circuit board so called PCB-drills.

[0003] Common grain growth inhibitors include vanadium, chromium, tantalum, niobium and / or titanium or compounds involving these. When added, generally as carbides, they limit grain growth during sintering, but they also have undesirable side effects such as unfavorably affecting the toughness behavior. Additions of vanadium or chromium are particularly detrimental and have to be ke...

Claims

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