Today, advanced high-strength steels have evolved greatly because of the need to increase the safety of the occupants of cars and to save on fuel consumption, due to the ability to withstand static and dynamic forces, especially in crashes. This advantage of steel makes it possible to make components with complex shapes and upgraded designs with shaping processes. The steel has a multiphase microstructure-evaporated polystyrene, which contains a ferrite field with hard phases inside it. This alloy has different amounts of residual austenite. Also, this alloy usually contains some of the phases of carbide bainite in the field of soft ferrite. In these steels austenite is transformed into martensitic during plastic deformation. Spot welding is the most important and most widely used welding process in steel plate joints in the automotive industry. In the past, many efforts have been made to achieve the optimal structure and properties for advanced high-strength steels, such as steel with expanded plastics with more sophisticated design, but the knowledge is still limited. In this steel, the alloying elements limit the welding ability and the thermal cycle of the welding process eliminates the carefully designed structure, which in turn results in the loss of mechanical properties of the resulting weld. The study of steel weldability with the plasticity due to degradation in the spot resistance welding process is one of the most important applications in the body of the vehicle, and its study has important scientific and practical justifications. Therefore, the heat treatment after welding was designed to improve metallurgical properties with pulsed streams of 6kA, 9kA and 12kA after initial boiling with 10kA current. Pulse welding is a heat-free operation after the boiling, which re-melt the central portion of the primary boiling knob and anneal the adjacent area of ??the FZ. The effect of the second pulse on mechanical and microstructural properties was investigated using electron microscopy and shear traction and cross-traction tests. In pulses, the second microstructure consisted of refined martensitic blocks and smaller ones. The failure of the welds was tested by CTS for pulsed samples of 6kA and 9kA PO. Due to the microstructure including the coaxial dendritic and smaller in FZ in the pulsed 9kA, the maximum fracture energy and maximum force were observed. A significant decrease in the FZ hardness in kA6 was observed in the nanoscale results, which was used to heat the martensitic and ferrite Attributed. The highest ratio of CTS / TSS was obtained for 6kA and 9kA, respectively, and the power shift in kA9 was maximal. The levels were dimples. The results of partial failure revealed separation in the coherent boundaries of the coarse aggregate region of the Anil region. Keywords: Resistance Spot welding, Transformation induced Plasticity, Microstructure, Mechanical Properties, and Second Pulse.