Method for making sintered body with metal powder and sintered body prepared therefrom

Abstract

The present invention relates to a metal powder sintered body by using fine powders as the raw material and the fabrication method thereof. The sintered body has a characteristic composition including iron (Fe), carbon (C), nickel (Ni) and at least one strengthening element, in the ratios as follows: Ni: 3.0-12.0%, carbon: 0.1-0.8%, the strengthening element: 0.5-7.0%, and the remaining portion being Fe. The sintered body has high tensile strength, high hardness, and good ductility, without treatment with the quenching process.

1 . A metal powder sintered body by using fine powders as a raw material, and an alloy of the sintered body comprising: 
 Iron (Fe), Carbon (C), Nickel (Ni) and at least one strengthening element, wherein the alloy includes 3.0-12.0% nickel, 0.1-0.8% carbon, and 0.5-7% the strengthening element, while a remaining portion of the alloy is iron, and diameters of the fine powders range from 0.1-30 μm.    
     
     
         2 . The sintered body as recited in  claim 1 , the strengthening element is selected from the group consisting of Molybdenum (Mo), Chromium (Cr), Copper (Cu), Titanium (Ti), Aluminum (Al), Manganese (Mn), Silicon (Si), and Phosphorous (P).  
     
     
         3 . The sintered body as recited in  claim 1 , wherein a source of carbon is from graphite.  
     
     
         4 . The sintered body as recited in  claim 1 , wherein a source of carbon is from carbonyl iron powder.  
     
     
         5 . The sintered body as recited in  claim 1 , wherein the sintered body has a tensile strength over 1400 MPa, a hardness over HRC35, and a ductility over 1%.  
     
     
         6 . A method for fabricating the sintered body as recited in  claim 1 , comprising: 
 providing powders and binders;    kneading the powders and the binders, so that the powders and the binders mix into a homogenous feedstock;    performing an injection molding process so as to discharge the feedstock to obtain a green compact;    debinding the green compact to remove the binders in order to form a body;    sintering and cooling the body in a sintering furnace; and    performing a post-sintering thermal process.    
     
     
         7 . The method as recited in  claim 6 , wherein the powders are elemental powders or prealloyed powders with diameters ranging from 0.1˜30 μm.  
     
     
         8 . The method as recited in  claim 6 , wherein the sintering furnace is a vacuum furnace or a continuous furnace.  
     
     
         9 . The method as recited in  claim 6 , wherein sintering conditions for the sintered body include a sintering temperature of 1100-1350° C. for 0.5-5 hours, and a cooling rate of 3-30° C./minute.  
     
     
         10 . The method as recited in  claim 6 , wherein the post-sintering thermal process is a low temperature tempering process, with a tempering temperature ranging from 150-400° C. for 0.5-5 hours.  
     
     
         11 . The method as recited in  claim 6 , wherein the sintered body has a tensile strength over 1400 MPa, a hardness over HRC35, and a ductility over 1%.  
     
     
         12 . A method for fabricating the sintered body as recited in  claim 1 , comprising: 
 providing powders and binders;    performing a powder granulation process so that the powders and the binders are joined into round granules;    sieving the round granules to select granules with a predetermined flowability for a compacting machine;    performing a compacting process by filling the granules in a die cavity and pressing them out, so as to generate a green compact;    debinding the green compact to remove the binders to form a body;    sintering and cooling the body inside a sintering furnace; and    performing a post-sintering thermal procedure.    
     
     
         13 . The method as recited in  claim 12 , wherein the powders are elemental powders or prealloyed powders with diameters ranging from 0.1˜30 μm.  
     
     
         14 . The method as recited in  claim 12 , wherein the sintering furnace is a vacuum or a continuous furnace.  
     
     
         15 . The method as recited in  claim 12 , wherein sintering conditions for the sintered body include a sintering temperature of 1100-1350° C. for 0.5-5 hours, and a cooling rate of 3-30° C./minute.  
     
     
         16 . The method as recited in  claim 12 , wherein the post-sintering thermal process is a low temperature tempering process, with a tempering temperature ranging from 150-400° C. for 0.5-5 hours.  
     
     
         17 . The method as recited in  claim 12 , wherein the sintered body has a tensile strength over 1400 MPa, a hardness over HRC35, and a ductility over 1%.