WEAR RESISTANT SINTERED ALLOY FOR VALVE SEAT AND MANUFACTURING METHOD THEREOF

摘要

PURPOSE: A wear resistant sintered alloy for valve seat is provided which improves wear resistance and formability by containing iron as a principal constituent, carbon, chromium, molybdenum, vanadium, tungsten, silicon, manganese and lead, and a manufacturing method thereof is provided. CONSTITUTION: The method comprises first process of press molding the blended alloy to a surface pressure of 5 to 8 tons/cm¬2 by blending a principal constituent of iron, 1.2 to 1.7 wt.% of carbon, 3.5 to 5.0 wt.% of chromium, 2.0 to 4.0 wt.% of molybdenum, 3.0 to 5.0 wt.% of vanadium, 7.0 to 10.0 wt.% of tungsten, 2.0 to 3.5 wt.% of cobalt, 0.1 to 1.0 wt.% of boron nitride, 0.2 to 0.4 wt.% of sulfur, 0.2 to 0.5 wt.% of manganese and 10.0 to 15.0 wt.% of lead; second process of air cooling the sintered alloy after sintering the press molded alloy at a temperature of 1,140 to 1,180 deg.C after finishing the first process; third process of subzero cooling the air cooled sintered alloy to a temperature of -200 to -600 deg.C after finishing the second process; fourth process of impregnating the subzero cooled alloy with lead at a temperature of 450 to 550 deg.C after finishing the third process; and a process of manufacturing the wear resistant sintered alloy for valve seat by passing the lead impregnated alloy through barrel process at a temperature of 450 to 550 deg.C after finishing the fourth process.