| 摘要 |
PURPOSE:To prepare the metal mold with high performance for cold forging by a method wherein the metal mold formed from an alloy with a specific component composition is carburized under vacuum at a predetermined temp. or below and, after the carbon therein is diffused at a predetermined temp., tempered at a predetermined temp. or more by cooling. CONSTITUTION:The alloy comprises, on the % basis, 0.40-0.70 C, 1.50 or less Si, 1.50 or less Mn, 1.50 or less Ni, 2.0-5.0 Cr, 2.0-5.0 Mo, 2.0-6.0 W, 0.5- 1.50 V, and the balance of Fe. The metal mold formed from this alloy is subjected to the carburizing treatment in a vacuum carburizing furnace regulated at the temp. of 1050 deg.C or less. Subsequently, the invaded carbon is sufficiently diffused by raising the temp. therein to 1050-1150 deg.C and a martensite structure is formed by cooling. Moreover, the tempering is carried out at 550 deg.C or more to obtain the metal mold with excellent abrasion resistance and autiseizure property. Moreover, one or more kinds of components selected from 2.0 or less Co, 0.50 or less Ti, 0.50 or less Nb and 0.50 or less Zr can be added to above described composition. |
