The HAZ in GTAW joint is attributed to the low welding speed and high heat input used in the experiment. It causes to the fusion pool longer residence in high temperature zone and slower cooling rate, while for the EBW, higher welding speed and lower heat-input are adopted. The size of fusion pool is small and the cooling rate is very fast. Moreover in the cooling process, the grains between parent material and fusion zone have no time to grow up. It should be noted that the HAZ is absent in EBW joints which results the higher tensile strength as compared to GTAW and FRW joints (Fig. 6, Fig. 7 and Fig. 8). Furthermore, high heat-input was likely to induce the micro-segregation of alloying elements and formation of Cr-depleted zones, resulting in the degradation in mechanical properties for the GTAW joint [31]. Since the formation of the Cr carbides is caused by exposure to the temperature range of 773–1073 K, rapid cooling rate and shorter exposure time to the sensitization temperatures in EBW joints are preferable for prevention of sensitization and reduce the amount of Cr-rich carbides formed on the grain boundaries [32] and [33]. Therefore, a significant improvement in mechanical properties can be achieved in EBW joints when compared with GTAW and FRW joints. In FRW joints volume of viscous material transferred at the weld interface decreases as a result of more mass discarded from the welding interface, which resulted in lower tensile strength.