| 摘要 |
PROBLEM TO BE SOLVED: To provide vacuum carburizing method and device capable of obtaining uniform carburization even in the case the surface area of the material to be charged is large in vacuum carburizing for a steel material. SOLUTION: In this vacuum carburizing method, as carburizing gas to be fed to a vacuum carburizing furnace, any of (a) a gaseous mixture obtd. by mixing, by volume, <50% inert gas contg. gaseous nitrogen into ethylene, (b) a gaseous mixture obtd. by mixing <40% hydrogen into ethylene, (c) a gaseous mixture obtd. by mixing <50% inert gas contg. gaseous nitrogen into a gaseous mixture obtd. by mixing <40% methane or ethane as chain saturated gaseous hydrocarbon or unsaturated propylene into ethylene or (d) a gaseous mixture obtd. by mixing <50% inert gas contg. gaseous nitrogen into a gaseous mixture obtd. by mixing <20% acetylene as chain unsaturated gaseous hydrocarbon into the ethylene is used, and the pressure in the carburizing stage is in the range of 1 to 10 kPa.
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