Y. Shimosato, M. Kamitani, H. Nakatsu, Chugai Ro Co Ltd., Osaka, Japan

Summary: URX gas carburizing is an accelerated gas carburizing method with 50% CO + 50% H2 gas which comes from CH4 gas + CO2 gas. By using this gas composition, the carburizing reaction rate increases to the maximum and the controllability of carbon potential improves. A carbon mass flow density is the product of the carburizing reaction rate multiplied by the difference of carbon percent between carbon potential of the gas and the carbon content of the surface of treated steel parts. We have obtained excellent results from the experimental tests at our laboratory as mentioned below. 1) Carburizing time can be shortened by 40% for 0.5 – 0.9 mm effective case depth 2) Uniform carburizing case depth 3) Less internal oxidation with the same case depth We have already developed the new roller hearth type continuous carburizing furnace and the new URX gas generator.