Microstructure and mechanical properties of Q235 steel welded joint in pulsed and un-pulsed ultrasonic assisted gas tungsten arc welding

Pulsed ultrasonic assisted gas tungsten arc welding (PU-GTAW) is a newly developed welding method. In this work, the PU-GTAW and un-pulsed ultrasonic assisted gas tungsten arc welding (U-GTAW) was comparative investigated by analyzing the microstructure and mechanical properties of Q235 welded joints. The results showed that the improvement of PU-GTAW on microstructure was more efficient than that of the U-GTAW. The weld seam grain size in the U-TIG and PU-GTAW was refined compared with that of the conventional GTAW. Compared with the conventional GTAW, the change of texture type and the decrease of texture intensity were obtained in the U-TIG and PU-GTAW. The sizes of microstructures in the U-GTAW and PU-GTAW were reduced compared with that of the GTAW, which was caused by the refinement grain. Influence degree of the U-GTAW and PU-GTAW on the hardness of the weld seam was the same. The hardness was increased by about 30HV compared with that of the conventional GTAW.