Investigation on Process and Welded Joint Mechanical Properties of Bainitic Steel Rail Flash Butt Welding

Abstract

Combine with the characteristics of bainitic rail U20Mn2SiCrNiMo, the flash butt welding process that suitable bainitic rail is optimized for improving bainitic joints’ performance basing on the mature technology of pearlitic rail flash butt welding, through approaches of lower heat input appropriate and matched upset forging length parameters, et.. In the post welding treatment, controlling the heating process strictly and using slow cooling measures are done to further optimize the properties of the welded joints. Then the performance tests are done on the bainitic rail joints welded with optimized welding and post welding process. The study results approve that the qualified bainitic rail joints can be obtained through appropriate flash butt welding process. Tensile strength and impact energy of bainitic joints are superior to pearlitic rail joints, but the elongation is reverse. The impact fracture of bainitic rail flash welded joints appear more defects such as hot cracks and silicate inclusions than pearlitic joints. Compared with parent metal, both types of the rail joints appear higher strength, but lower elongation and impact energy. The decreased percentage of bainitic rail joints compared with their parents is larger than pearlitic joints.