We investigate the influence of the chemical composition of a weld metal on the long-term crack resistance under static loading in NACE hydrogen-sulfide solution. The effect of C, S, P, Mn, Si, Ni, Cu, V, Zr, Co, B, and Mo on corrosion-mechanical properties of welds is established. Welds containing about 0.11-0.14% C are shown to have the highest crack resistance. The optimum concentrations of manganese (-0.6%) and silicon (-0.3%), at which the maximum values of K 1 ssc are obtained, are found. The admissible manganese and silicon contents are 0.39-1.0% and 0.2-0.5%, respectively. The susceptibility to cracking increases with sulfur and phosphorus contents. The highest values of Kl,~sc were obtained at a sulfur content of 0.004 to 0.014% and at a phosphorus content of 0.014 to 0.023%. The adverse influence of these elements in welds is manifested to a lesser extent than in the rolled metal. Alloying with boron is inexpedient and dangerous. Joint alloying with 0.4-0.54% Cu and 0.1-0.3% Ni improves the crack resistance. The influence of molybdenum is analogous (Kissc increases by 29-50%). Alloying with 0.5% Co and 0.05% Zr results in the formation of nonequilibrium structures. In this case, K l .~sc is close to those of welds made with carbon steel electrodes. On alloying with 0.2% V, the fine structure forms, and K I ssc decreases by 20-30%. Alloying with vanadium in these amounts is inadmissible. Preference should be given to complex microalloying.In hydrogen-sulfide environments, the time of serviceability of steel parts of oil-gas equipment decreases as a result of hydrogen-sulfide corrosion and hydrogen-sulfide stress cracking [1][2][3]. The most critical regions of structures are welded joints [4,5], which is due to the thermodeformation cycle of welding responsible for the structuralelectrochemical inhomogeneity of various zones of welds and development of residual stresses. The aim of the present work is to establish the influence of the chemical composition of a weld metal on the resistance to crack growth under static loads in hydrogen-sulfide environments. We investigated specimens made of welded steel plates 14 mm thick with centrally located weld. We used steel 09G2FB of the following chemical composition: 0.10% C, 1.70% Mn, 0.35% Si, 0.09% V, 0.05% Nb, 0.01% S, and 0.02% P. In terms of mechanical parameters, namely Ou = 640MPa, (~y = 470MPa, 8 = 21%, ~ = 31%, it corresponds, according to the Standard API-5L, to the strength class of steel Kh60 (~u > 527 MPa, (Yy _> 422MPa).Welding was performed with industrial and experimental electrodes. The industrial electrodes of Schwartz 3K (Germany), FoxEV50 (Austria), LB-52U (Japan), OZS/VNIIST-26 (Russia), UONI 13/55, and MP-3 (Ukraine) brands are used in the construction of pipeline systems for transporting aggressive technological media containing hydrogen sulfide [4]. Some of electrodes are alloyed with molybdenum, nickel, and copper. The special alloying of the weld metal was performed by using experimental electrodes with basic coating of the main type (E...
