High speed tool steel produced by sintering powder and method of producing same
AssigneeHitachi Metals, Ltd.
InventorsJunichi Nishida, Norimasa Uchida
Life of this patent
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Abstract
A high speed tool steel produced by sintering powder, consisting essentially, by weight, of more than 1.5% but not more than 2.2% C, not more than 1.0% Si, not more than 0.6% Mn, 3.0 to 6.0% Cr, an amount of W and Mo in which the content of W+2Mo is in the range of 20 to 30% and in which the ratio of W/2Mo is not less than 1, not more than 5.0% V, 2.0 to 7.0% Nb, the ratio of Nb/V being not less than 0.5, and the balance Fe and incidental impurities, the value of C-Ceq, which Ceq is defined by 0.24+0.033.times.W+0.063.times.Mo+0.2.times.V+0.1.times.Nb, being in a range of -0.20 to 0.05, the density of carbides in the sintered steel having grain size of 2 to 5 .mu.m being in a range of 10,000 to 30,000 pieces/mm.sup.2.
Claims11
A sintered high speed tool steel produced by sintering powder, said powder consisting essentially, by weight, of more than 1.5% but not more than 2.2% C, not more than 1.0% Si, not more than 0.6% Mn, 3.0 to 6.0% Cr, an amount of W and Mo in which the content of W+2Mo is in the range of 20 to 30% and in which the ratio of W/2Mo is not less than 1, not more than 5.0% V, 2.0 to 7.0% Nb, the ratio of Nb/V being not less than 0.5, and the balance Fe and incidental impurities, the value of C-Ceq, while Ceq is defined by 0.24+0.033.times.W+0.063.times.Mo+0.2.times.V+0.1.times.Nb, being in a range of -0.20 to 0.05, at least some of the C in said sintered steel being in the form of carbides of grain size 2 to 5 .mu.m, said carbides in said sintered steel having a grain size of 2 to 5 .mu.m being present in an amount in the range of 10,000 to 30,000 pieces/mm.sup.2.
A sintered high speed tool steel produced by sintering powder, said powder consisting essentially, by weight, of more than 1.5% but not more than 2.2% C, not more than 1.0% Si, not more than 0.6% Mn, 3.0 to 6.0% Cr, an amount of W and Mo in which the content of W+2Mo is in the range of 20 to 30% and in which the ratio of W/2Mo is not less than 1, not more than 5.0% V, 2.0 to 7.0% Nb, the ratio of Nb/V being not less than 0.5, not more than 15.0% Co, and the balance Fe and incidental impurities, the value of C-Ceq, which Ceq is defined by 0.24+0.033.times.W+0.063.times.Mo+0.2.times.V+0.1.times.Nb, being in a range of -0.20 to 0.05, at least some of the C in said sintered steel being in the form of carbides of grain size 2 to 5 .mu.m said carbides in said sintered steel having a grain size of 2 to 5 .mu.m being present in an amount in the range of 10,000 to 30,000 pieces/mm.sup.2.
A sintered high speed tool steel produced by sintering powder, said powder consisting essentially, by weight, of more than 1.5% but not more than 2.2% C, not more than 1.0% Si, not more than 0.6% Mn, 3.0 to 6.0% Cr, an amount of W and Mo in which the content of W+2Mo is not less than 1, not more than 5.0% V, 2.0 to 7.0% Nb, the ratio of Nb/V being not less than 0.5, 4.0 to 15.0% Co, and the balance Fe and incidental impurities, the value of C-Ceq, which Ceq is defined by 0.24+0.033.times.W+0.063.times.Mo+0.2.times.V+0.2.times.Nb, being in a range of -0.20 to 0.05, at least some of the C being in the form of carbides of grain size 2 to 5 .mu.m said carbides in said sintered steel having a grain size of 2 to 6 .mu.m being present in an amount in the range of 10,000 to 30,000 pieces/mm.sup.2 .
A method of producing sintered high speed tool steel produced by sintering powder comprising
- selecting said alloy powder to consist essentially, by weight, of more than 1.5% but not more than 2.2% C, not more than 1.0% Si, not more than 0.6% Mn, 3.0 to 6.0% Cr, an amount of W and/or Mo in which the content of W+2Mo is in the range of 20 to 30% and in which the ratio of W/2Mo is not less than 1, not more than 5.0% V, 2.0 to 7.0% Nb, the ratio of Nb/V being not less than 0.5, and the balance Fe and incidental impurities, the value of C-Ceq, which Ceq is defined by 0.24+0.033.times.W+0.063.times.Mo+0.2.times.V+0.1.times.Nb, being in a range of -0.20 to 0.05;
- sintering said alloy powder to obtain a sintered material wherein at least some of the C in said sintered steel being in the form of carbides of grain size 2 to 5 .mu.m;
- and
- heating said sintered material at 1100.degree. C. to 1200.degree. C. so that the amount of said carbides having grain size of 2 to 5 .mu.m is in the range of from 10,000 to 30,000 pieces/mm.sup.2.
A method of producing high speed tool steel produced by sintering powder comprising
- selecting said alloy powder to consist essentially, by weight, of more than 1.5% but not more than 2.2% C, not more than 1.0% Si, not more than 0.6% Mn, 3.0 to 6.0% Cr, an amount of W and/or Mo in which the content of W+2Mo is in the range of 20 to 30% and in which the ratio of W/2Mo is not less than 1, not more than 5.0% V, 2.0 to 7.0% Nb, the ratio of Nb/V being not less than 0.5, not more than 15.0% Co, and the balance Fe and incidental impurities, the value of C-Ceq, which Ceq is defined by 0.24+0.033.times.W+0.63.times.Mo+0.2.times.V+0.1.times.Nb, being in a range of -0.20 to 0.05;
- sintering said alloy powder to obtain a sintered material;
- and
- heating said alloy powder at 1100.degree. C. to 1200.degree. C. so that the amount of said carbides having grain size of 2 to 5 .mu.m is in the range of 10,000 to 30,000 pieces/mm.sup.2.
Dependencies are inferred from the claim text.