| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide alloy steel having high temperature corrosion resistance, wear resistance and toughness by controlling MC type carbides in melted alloy steel which has an economical advantage as well, and having cost effectiveness since expensive Co and powder steel are not used, to provide a screw for an injection molding machine using the alloy steel, and to provide an assembled component thereof. <P>SOLUTION: The screw for injection molding machine is produced using melted alloy steel having a composition comprising, by weight, 0.9 to 1.5% C, 0.1 to 2% Si, 0.1 to 1% Mn, 3 to 14% Cr, 0.1 to 7% Mo, 0.1 to 7% W, 1 to 5% V and 0.1 to 0.2% Nb, and the balance Fe with inevitable impurities as the stock, and, among MC type carbides present on the surface of the cut face parallel to the surface layer part in the face in contact with a molding material, the diameter of an equivalent circle in the maximum grains lies in the range of 4 to 15μm, and also, among the MC type carbides having the diameter of an equivalent circle of≥4μm,≥45% of the grains are composed of relatively spherical grains in which the ratio between the major axis and the minor axis in the cross-section of the grains is≥0.5. <P>COPYRIGHT: (C)2007,JPO&INPIT</p> |
