Segregation of Boron in Ultra Low Carbon Microalloyed Steels Containing Copper during Continuous Cooling

By means of particle tracking autoradiography(PTA),the segregation of boron to grain boundaries in ultra low carbon microalloyed steels during cooling from 1 150℃ to 850℃ at 5℃/s was investigated.The enrichment factors and widths of boron depletion zone were measured at different temperatures,and the effect of copper on the segregation of boron was analyzed.It is found that the concentration of boron on the grain boundary increases in the beginning cooling stage and reaches its maximum at about 1 090℃;after that,it decreases gradually to a minimum with temperatures decreasing to 940℃;and then,it increases again.