Composite rotary tool and tool fabrication method

A composite rotary tool comprising:

• an elongate portion including at least a first region and a second region, said elongate portion defining at least one helically oriented cutting edge;
• said first region comprising a first cemented carbide material;
• said second region comprising a second cemented carbide material differing from said first region in at least one of modulus of elasticity, hardness, wear resistance, fracture toughness, tensile strength, corrosion resistance, coefficient of thermal expansion, and coefficient of thermal conductivity, wherein said second region comprises less than 5% cubic carbides by weight;
• said first region autogenously bonded to said second region;
• and
• said first region and said second region coaxially disposed with said second region surrounding at least a portion of said first region, said helically oriented cutting edge defined by said second region.

An endmill or drill bit comprising:

• an elongate portion comprising coaxially disposed core and outer regions, said elongate portion defining a helically oriented cutting edge;
• said core region comprising a first cemented carbide material having a modulus of elasticity from 90×(10)6 psi to 95×(10)6 psi;
• said outer region comprising a second cemented carbide material having a different modulus elasticity from 69×(10)6 psi to 92×(10)6 psi;
• and
• said core region autogenously bonded to said outer region.

An endmill or drill bit comprising:

• an elongate portion comprising coaxially disposed core and outer regions, said elongate portion defining a helically oriented cutting edge;
• said core region comprising a first cemented carbide material comprising, by weight, 0.2 to 0.6% chromium;
• a said outer region comprising a second cemented carbide material differing from said first cemented carbide material in at least one characteristic, wherein said outer region comprises less than 5% cubic carbides;
• and
• said core region autogenously bonded to said outer region.

A composite rotary tool comprising:

• an elongate core region, said core region comprising a core cemented carbide material;
• a first region comprising a first cemented carbide material different than said core cemented carbide material in at least one characteristic and defining a first helically oriented cutting edge, said first region coaxially disposed to said core region;
• a second region comprising a second cemented carbide material differing from said first cemented carbide material and said core cemented carbide material in at least one characteristic and said second region defining a second helically oriented cutting edge different in at least one dimension than said first helically oriented cutting edge;
• said first region and second region autogenously bonded to said core region.