New electrodes of ANV-70BG grade were developed. Relationship of structural and chemical inhomogeneity in transition zone between low-carbon steel and highly-alloyed deposited metal depending on type of the latter and value of welding current was investigated. 4 Ref., 4 Tables, 3 Figures.

Causes for fracture of repair layer deposited with electrodes of E-08Kh20N9G2B type on the surface of St3sp (killed) steel lining of water wheel chamber of HPS hydraulic unit are analyzed. It is established that its failures (cracking, delamination) arise as a result of lower chromium content (less than 12 %) and formation of martensite phase in the transition zone between steel St3sp and high-alloyed deposited metal. State of transition zone between St3sp and deposited metal of E-10Kh25N13G2, E-11Kh15N25M6AG2 and 10Kh28N14G2 type at welding current variation in the range of 80-140 A has been studied. It is shown that sufficient content of chromium (less than 12 %) and absence of martensite in the transition zone can be ensured in the case of application of electrodes of 10Kh28N14G2 type for repair surfacing at limitation of Iw to not more than 90 A. 6 Ref., 5 Figures, 1 Table.

The paper gives the results of investigations of variation of weld metal composition and structure in coated-electrode wet underwater arc welding of 12Kh18N10T steel. It is shown that unlike welding in air, in underwater welding the content of oxygen and hydrogen increases in the weld metal with simultaneous lowering of the quantity of ferritizers. Weld metal structure is characterized by presence of predominantly columnar crystallites, decreased fraction of grain-boundary δ-ferrite and increased volume fraction of oxide non-metallic inclusions, the quantity of which with 0.10 to 1.25 μm dispersion rises 1.5 to 2 times. 14 Ref., 4 Tables, 2 Figures.

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