Sintered material for aluminum die casting and manufacturing method thereof

Abstract

A sintered material for aluminum die casting can prevent the strength from being lowered even after steam treatment. The sintered material for aluminum die casting is a sintered material used as an insert at the time of aluminum die casting, and contains Cr: 0.71 to 0.97 wt %, Mo: 0.10 to 0.20 wt %, and C: 0.64 to 0.87 wt %, with the remainder being Fe and other unavoidable impurities.

1 . A sintered material used as an insert in aluminum die casting, the sintered material comprising:
 Cr: 0.71 to 0.97 wt %;   Mo: 0.10 to 0.20 wt %; and   C: 0.64 to 0.87 wt %;   wherein the remainder comprises Fe and other unavoidable impurities.   
     
     
         2 . The sintered material of  claim 1 , further comprising one or two or more selected from the group consisting of Mn, Ni and S;
 wherein a total content of Mn, Ni and S is in a range of 0.15 to 0.45 wt %.   
     
     
         3 . The sintered material of  claim 1 , wherein the sintered material does not contain Cu. 
     
     
         4 . The sintered material of  claim 1 , wherein the sintered material has a yield strength of 400 MPa or more, and a fatigue strength of 150 MPa or more. 
     
     
         5 . The sintered material of  claim 1 , wherein the sintered material has a density of 6.8 to 7.2 g/cm3. 
     
     
         6 . The sintered material of  claim 1 , wherein on a surface of the sintered material, a surface protective layer made of iron oxide is formed. 
     
     
         7 . The sintered material of  claim 6 , wherein Cu is not crystallized in the surface protective layer. 
     
     
         8 . A method of manufacturing a sintered material for aluminum die casting, the method comprising:
 preparing an iron-based pre-alloy powder containing chromium (Cr) and molybdenum (Mo);   preparing an iron-based pre-alloy mixture by mixing carbon powder, a functional additive, and a lubricant with the iron-based pre-alloy powder;   preparing a molded material by molding the iron-based pre-alloy mixture;   preparing a sintered material by sintering the molded material; and   steam-treating the sintered material;   wherein the iron-based pre-alloy powder further includes Mn, Ni, and S; and   wherein a total content of Mn, Ni and S is in a range of 0.15 to 0.45 wt %.   
     
     
         9 . The method of  claim 8 , wherein the iron-based pre-alloy powder contains Cr: 0.72 to 0.98 wt %, and Mo: 0.10 to 0.20 wt %, wherein the remainder comprises Fe and other unavoidable impurities. 
     
     
         10 . (canceled) 
     
     
         11 . The method of  claim 8 , wherein the iron-based pre-alloy powder does not contain Cu. 
     
     
         12 . The method of  claim 8 , wherein the iron-based pre-alloy mixture is prepared by mixing a functional additive and a lubricant with the iron-based pre-alloy powder, so that the iron-based pre-alloy mixture contains Cr: 0.71 to 0.97 wt %, Mo: 0.10 to 0.20 wt %, C: 0.63 to 0.87 wt %, functional additive: 0.10 to 0.20 wt %, and lubricant: 0.54 to 0.66 wt %, wherein the remainder comprises Fe and other unavoidable impurities. 
     
     
         13 . The method of  claim 8 , wherein the sintered material contains Cr: 0.71 to 0.97 wt %, Mo: 0.10 to 0.20 wt %, C: 0.64 to 0.87 wt %, and functional additive: 0.10 to 0.20 wt %, wherein the remainder comprises Fe and other unavoidable impurities. 
     
     
         14 . The method of  claim 8 , wherein the preparing of the sintered material comprises sintering the molded material at a temperature of 1100 to 1150° C. for 20 to 60 minutes in a nitrogen and hydrogen mixed gas atmosphere, and then air-cooling the molded material. 
     
     
         15 . The method of  claim 8 , wherein the steam-treating of the sintered material comprises treating the sintered material in a steam atmosphere at a temperature of 400 to 600° C. for 30 to 60 minutes. 
     
     
         16 . The method of  claim 15 , wherein in the steam-treating of the sintered material, on a surface of the sintered material, a surface protective layer made of iron oxide is formed. 
     
     
         17 . The method of  claim 16 , wherein in the steam-treating of the sintered material, Cu is not crystallized in the surface protective layer. 
     
     
         18 . The method of  claim 8 , wherein after the steam-treating of the sintered material, the microstructure of the sintered material is pearlite.