Microstructures and mechanical properties of low carbon fishplate materials

Two kinds of low carbon bainite materials were developed for fishplate usage.The microstructures and mechanical properties were measured in details.The results showed that one material was composed of fine granular bainite with the yield strength of 722 MPa at room temperature and 738 MPa at-55℃, and elongation percentages of 60.7% and 41.7%, respectively.The other one had a meta-bainite microstructure with corresponding strengths of 568.5 MPa and 700 MPa, elongation percentages of 63.5% and 67.1%, respectively.These values are all superior to the home-made B7 steel and the fishplate materials made in Japan.The major strengthening mechanisms were discussed and attributed to the solid solution, complex phases, fine grain and dislocation strengthening.