Abstract：Aiming HRB500 high strength steel bars with good engineering application prospects structures, specimens connected by flash butt welding were conducted tested, and the parameters, such as the mechanical properties, Vickers hardness, metallographic microstructure and fatigue strength, were studied and analyzed. It is concluded that the welding properties of HRB500 high strength steel bars perform satisfactorily, and there are no obvious change in strength and cold bending mechanical properties of base metal and weldments. The tensile fracture appearances of the welded pieces have obvious ductile fracture characteristics, and the fractures are far away from the welding positions. Bainite is produced in the welding joint area by flash butt welding, and Vickers hardness increases first and then decreases from the base metal to the welding position. Vickers hardness of the welding position is nearly equal to that of the base metal. The fatigue strength and development law of base metal and weldments are obtained by the S-N curve model and staircase method. The fatigue life of welded specimens are more discrete and generally lower than the fatigue life of base metal. The fatigue strength of the welded parts decline more obviously than that of the base metal when the 2 million times fatigue loads are applied. Corresponding to the 107 times fatigue loads, the fatigue strength of base metal and weldments are about 36% of that for the base metal. Fatigue failures of weldments mostly occur in weld position, and have obvious fatigue failure characteristics.
