We study the electrochemical and microelectrochemical characteristics and the microhardness of a fragment of a pipe made of 17G1SU steel with a weld made by FOX EV 50, Basic One, and UONII-13/55R electrodes. The corrosion potentials of different layers of the weld and heat-affected zones around them increase the electrochemical heterogeneity up to ∼ 130 mV as compared with the base metal. The corrosion currents of the base metal differ by ∼ 15 %, and the corrosion currents of different layers of the weld differ by at most 69 %. The microelectrochemical heterogeneities of different zones of the welded joint determined by the moving-drop method differ insignificantly (ΔE = 20–80 mV). Only the weld made by the FOX EV 50 electrode has a somewhat higher microelectrochemical heterogeneity (ΔE = 25–95 mV). For all electrodes, the microhardness of the base metal and heat-affected zone up to the fusion line remains unchanged (1.6–2.25 GPa), but for the weld made by the FOX EV 50 electrode it is lower (1.2–1.4 GPa) than for the welds made by the Basic One and the UONII-13/55R electrodes (1.6–2.2 GPa).