Tool steel alloy with high thermal conductivity

Abstract

A hot-work tool steel alloy comprising 0.26 to 0.55% by weight C, <2% by weight Cr; 1 to 10% by weight Mo, and W in a concentration of up to 15% by weight W. The tool steel has a thermal conductivity of more than 42 W/mK at room temperature. A process for making a hot-work steel having high thermal conductivity comprising formulating the hot-work tool steel alloy to comprise a microstructure comprising carbides in a surrounding metallic matrix, heat treating the hot-work tool steel alloy a) to reduce any fraction by weight of C, W, and Mo in solid solution in the matrix, b) to change a fraction by volume of carbides in the matrix, and c) to promote formation of a matrix composition and carbide fraction, distribution, and morphology that impart a thermal conductivity to the alloy of more than 42 W/mK at room temperature.

1 . A process for making a hot-work steel having high thermal conductivity comprising:
 formulating the hot-work tool steel alloy to comprise the following constituents in a microstructure comprising carbides in a surrounding metallic matrix:   0.26 to 0.55% by weight C;   <2% by weight Cr;   0 to 10% by weight Mo;   0 to 15% by weight W;   wherein a content of W and Mo in total amounts to 1.8 to 15% by weight;   carbide-forming elements Ti, Zr, Hf, Nb, Ta with a content of from 0 to 3% by weight individually or in total;   0 to 4% by weight V;   0 to 6% by weight Co;   0 to 1.6% by weight Si;   0 to 2% by weight Mn;   0 to 2.99% by weight Ni;   0 to 1% by weight S; and   remainder: iron and unavoidable impurities; and   heat treating the hot-work tool steel alloy a) to reduce any fraction by weight of C, W, and Mo in solid solution in the matrix, b) to change a fraction by volume of carbides in the matrix, and c) to promote formation of a matrix composition and carbide fraction, distribution, and morphology that impart a thermal conductivity to the alloy of more than 42 W/mK at room temperature.   
     
     
         2 . The process of  claim 1  wherein the heat treating biases the microstructure toward formation of primary and secondary carbides and increases electron and phonon density in the primary carbides. 
     
     
         3 . The process of  claim 1  wherein the heat treating increases a mean free length path for phonon and electron flow in the matrix surrounding the carbides. 
     
     
         4 . The process of  claim 2  wherein the heat treating increases a mean free length path for phonon and electron flow in the matrix surrounding the carbides. 
     
     
         5 . The process of  claim 1  wherein the alloy comprises:
 0.32-0.5 wt % C; 
 <1% wt % Cr; 
 3-7 wt % Mo. 
 
     
     
         6 . The process of  claim 1  wherein the alloy comprises:
 0.3-0.42 wt % C; 
 <1% wt % Cr; 
 2.5-4.5 wt % Mo; 
 1-2.5 wt % W. 
 
     
     
         7 . The process of  claim 1  wherein the alloy comprises:
 0.4-0.55 wt % C; 
 <1% wt % Cr; 
 0-4 wt % Mo. 
 
     
     
         8 . The process of  claim 1  wherein the alloy comprises:
 0.4-0.55 wt % C; 
 <1% wt % Cr; 
 3-5 wt % Mo; 
 2-4 wt % W; 
 0.7-1.5 wt % V. 
 
     
     
         9 . A hot-work tool steel alloy comprising:
 0.26 to 0.55% by weight C;   <2% by weight Cr;   1 to 10% by weight Mo;   W in a concentration of up to 15% by weight W;   wherein a content of W and Mo in total amounts to 1.8 to 15% by weight;   carbide-forming elements Ti, Zr, Hf, Nb, Ta with a content of from 0 to 3% by weight individually or in total;   0 to 4% by weight V;   0 to 6% by weight Co;   0 to 1.6% by weight Si;   0 to 2% by weight Mn;   0 to 2.99% by weight Ni;   0 to 1% by weight S; and   remainder: iron and unavoidable impurities; and   wherein the tool steel has a thermal conductivity of more than 42 W/mK at room temperature.   
     
     
         10 . The hot-work tool steel alloy of  claim 13  comprising:
 0.26 to 0.55% by weight C; 
 <2% by weight Cr; 
 0.5 to 7% by weight Mo; 
 0.5 to 7% by weight W; 
 0 to 4% by weight V; 
 0 to 6% by weight Co; 
 0 to 1.6% by weight Si; 
 0 to 2% by weight Mn; 
 0 to 2.99% by weight Ni; 
 0 to 1% by weight S; 
 wherein a content of W+Mo+V in total amounts to 2 to 10% by weight; 
 remainder: iron and unavoidable impurities; and 
 wherein the hot-work steel has a thermal conductivity of more than 42 W/mK at room temperature. 
 
     
     
         11 . The hot-work steel alloy of  claim 11  wherein the alloy comprises:
 0.32-0.5 wt % C; 
 <1% wt % Cr; 
 3-7 wt % Mo. 
 
     
     
         12 . The hot-work steel alloy of  claim 11  wherein the alloy comprises:
 0.3-0.42 wt % C; 
 <1% wt % Cr; 
 2.5-4.5 wt % Mo; 
 1-2.5 wt % W. 
 
     
     
         13 . The hot-work steel alloy of  claim 11  wherein the alloy comprises:
 0.4-0.55 wt % C; 
 <1% wt % Cr; 
 0-4 wt % Mo. 
 
     
     
         14 . The hot-work steel alloy of  claim 11  wherein the alloy comprises:
 0.4-0.55 wt % C; 
 <1% wt % Cr; 
 3-5 wt % Mo; 
 2-4 wt % W; 
 0.7-1.5 wt % V.