The effect of the graphitizing heat treatment and boron content on boron distribution in high carbon steel

It is convenient to analyze the distribution of boron in high carbon steel with boron, simply using neutron-induced radiography with a neutron fluency of 1.9 x 1013 [cm(-2)]. It was revealed by the neutron-induced radiography that the distribution of boron was dependent on boron contents, graphitizing temperature and time. The density of boron track increased with increasing boron contents. But the density of the boron track and graphite in high carbon steel graphitized at 700 degrees C is higher than that of high carbon steel graphitized at 750 degrees C. The density of graphite in high carbon steel also depends upon the content of boron and the graphitizing temperature. The shape of the boron track was changed from sphere to rod type when annealed at 800 degrees C, in steel containing 50 ppm of boron, due to different phases of boride. The distribution of boron segregation or boron-rich precipitates in high carbon steel was well documented with a neutron-induced radiography, but the direct relationship between graphite and boron was not clarified by it. Furthermore, the analysis of electron probe X-ray microanalyzer (EPMA) also showed that the high amount of boron coexisted with carbon in graphite in high carbon steel.