PSI - Issue 68

Oleksii Milenin et al. / Procedia Structural Integrity 68 (2025) 1010–1016 Oleksii Milenin et al./ Structural Integrity Procedia 00 (2025) 000–000

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4. Conclusions 1. Mathematical models and means of computer simulations have been developed to predict the combined processes of temperature field kinetics, phase transformations, hydrogen diffusion, and stress-strain state evolution during multi-pass in-service repair welding. These tools enhance the reliability and efficiency of welding practices by providing accurate predictions of material behavior under repair conditions from the point of view of susceptibility to cold cracking. 2. The probability of cold crack nucleation during multi-pass in-service repair welding, particularly for addressing local corrosion damage of main gas pipelines, has been numerically predicted. The models effectively account for varying hydrogen concentrations and provide a solid framework for evaluating crack formation risks. 3. A detailed analysis of hydrogen concentration, martensitic structure formation, and stress-state kinetics in pipe steels has yielded crucial insights into their susceptibility to cold cracking. The study confirmed that preheating the repair area significantly reduces cold cracking probability to acceptable levels, leading to established recommendations for optimal preheating parameters during in-service welding to mitigate local corrosion metal loss. Akhonin, S.V., Milenin, A.S, Pikulin, A.N. (2005). Modeling of processes of evaporation of alloying elements in EBSM of cylindrical ingots produced from Ti-base alloys. Problemy Spetsial'noj Electrometallugii, 1, pp. 21-25. Dmytrakh, I., Syrotyuk, A., Leshchak, R. (2022). Specific mechanism of hydrogen influence on deformability and fracture of low-alloyed pipeline steel. Procedia Structural Integrity, Vol. 36, pp. 298-305. Kiefner, J.F., Bruce, W.A., Stephens., D.R. (1994). Pipeline repair manual. Technical Toolboxes, Inc., Houston, 167 p. Lobanov L.M., Poznyakov V.D., Makhnenko O.V. (2013). Formation of cold cracks in welded joints from high-strength steels with 350-850 MPa yield strength. The Paton Welding Journal, 7, pp. 7-12. Makhnenko V.I., Korolyova T.V. and Lavrinets I.G. (2002). Effect of microstructural transformations on redistribution of hydrogen in fusion welding of structural steels. The Paton Welding Journal, 2, pp. 6-13. Makhnenko V.I., Poznyakov V.D., Velikoivanenko E.A., Makhnenko O.V., Rozynka G.F., Pivtorak N.I. (2009). Risk of cold cracking in welding of structural high-strength steels. The Paton Welding Journal, 12, pp. 2-6. Makhnenko, V.I., Velikoivanenko, E.A., Pochinok V.E. et al. (1999). Numerical Methods of the Predictions of Welding Stresses and Distortions. Welding and Surfacing/ Harwood academic publishers, Amsterdam, pp. 146. Meng, B., Gu, C.H., Zhang, L., Zhou, C.S., Li, X.Y., Zhao, Y.Z., Zheng, J.Y., Chen, X.Y., Han, Y. (2017). Hydrogen effects on X80 pipeline steel in high-pressure natural gas/hydrogen mixtures. International Journal of Hydrogen Energy, Vol. 42, Issue 11, 7404-7412. Velikoivanenko, E.A., Milenin, A.S., Popov, A.V., Sidoruk, V.A., Khimich, A.N. (2014). Methods and technologies of parallel computing for mathematical modeling of stress-strain state of constructions taking into account ductile fracture. Journal of Automation and Information Sciences, 46 (11), pp. 23-35. References