Study on Continuous Gas Carburizing (3rd Report)

Abstract

A report was previously made by us on the results obtained from our successful operation of the continuous gas carburizing furnace This time, a study was made on the effects of continuous gas carburizing on the toughness and the structure. The results were as follows: The effects on the structural and the mechanical properties were studied by observing the impact value, the hardness, and the structure of Cr-Mo steel, Ni-Cr steel and high carbon steel. The results revealed that (1) the impact value obtained from direct quenching by continuous gas carburizing was somewhat lower as compared with that of pack carburizing, but it coulde be recovered to a considerable degree by using a Ni-Cr steel or a fine grain steel in case Cr-Mo steel is employed, (2) the greatest influence on the ductility was shown by the heating temperature, (3) the ideal temperature for tempering is in the range of 180∼200° by which the ductility of martensite is highly increased, and (4) it is possible to judge the approximate ductility by fractions on the case part.