OBRABOTKAMETALLOV technology Vol. 25 No. 1 2023 temperature austenization, the δ-ferrite is not completely eliminated. Thus, to minimize the formation of this defect, optimization of the carbon and chromium composition, as well as austenization operation is required. Conclusion As aim of the work, detailed studies of the reasons for defects formation in the microstructure of 12-Cr18Ni10-Ti stainless steel are carried out; such as intergranular corrosion, martensitic phase and δ-ferrite. Recommendations for its elimination are formulated based on the results obtained and thermodynamic calculations. It is recommended to reduce the nitrogen and carbon content to 0.05% by methods of ladle liquid steel treatment to minimize the amount of Cr23C6 chromium carbides and, consequently, to increase the resistance of steel to intergranular corrosion. It is necessary to have titanium in steel at least 0.3% in accordance with GOST 5632-2014. Required reduction should be not more than 50% in order to prevent the formation of deformation martensite in stainless steel during cold drawing. In addition, it is recommended to optimize the chemical composition for chromium and carbon to reduce the temperature range of ferrite formation in order to avoid the presence of an excessive high-temperature ferrite phase in the structure. In all three cases, the operation of billets austenization in the temperature range of 1,050–1,100 °C is appointed. References 1. Urban D. Novye khromistye stali dlya ispol’zovaniya v usloviyakh vysokikh temperatur [New chromium steels for high temperature applications]. Chernye metally, 2018, no. 7, pp. 67–68. (In Russian). 2. Sizyakov V.M., Bazhin V.Yu., Patrin R.K., Feshchenko R.Yu., Saitov A.V. Features of high-amperage electrolyzer hearth breakdown. Refractories and Industrial Ceramics, 2013, vol. 54, pp. 151–154. 3. Gomes A., Navas M., Uranga N., Paiva T., Figueira I., Diamantino T.C. High-temperature corrosion performance of austenitic stainless steels type AISI 316L and AISI 321H, in molten Solar salt. Solar Energy, 2019, vol. 177, pp. 408–419. 4. Ayer R., Ro Y., Park I., Shim J., Nam J., Kim J. A computational approach to evaluate the sensitization propensities of UNS S32100 and UNS S34700 stainless steels. Corrosion 2018, Phoenix, Arizona, USA, 2018, p. NACE-2018-10574. Available at: https://onepetro.org/NACECORR/proceedings-abstract/CORR18/AllCORR18/NACE-2018-10574/125882 (accessed 26.01.2023). 5. Tynchenko V., Bukhtoyarov V., Rogova D., Myrugin A., Seregin Y., Bocharov A. Software for modeling brazing process of spacecraft elements from widely used alloys. 2022 21st International Symposium INFOTEH-Jahorina (INFOTEH), East Sarajevo, Bosnia and Herzegovina, 2022, pp. 1–5, DOI: 10.1109/INFOTEH53737.2022.9751246. 6. Morshed-Behbahani K., Najafisayar P., Pakshir M., Shahsavari M. An electrochemical study on the effect of stabilization and sensitization heat treatments on the intergranular corrosion behaviour of AISI 321H austenitic stainless steel. Corrosion Science, 2018, vol. 138, pp. 28–41. 7. Feng Z., Zecevic M., Knezevic M. Stress-assisted (γ→ α′) and strain-induced (γ→ ε→ α′) phase transformation kinetics laws implemented in a crystal plasticity model for predicting strain path sensitive deformation of austenitic steels. International Journal of Plasticity, 2021, vol. 136, p. 102807. 8. Wang J., Su H., Chen K., Du D., Zhang L., Shen Z. Effect of δ-ferrite on the stress corrosion cracking behavior of 321 stainless steel. Corrosion Science, 2019, vol. 158, p. 108079. 9. Hu D., Li S.L., Lu S. Effects of TIG process on corrosion resistance of 321 stainless steel welding joint. Materials Science Forum, 2013, vol. 749, pp. 173–179. 10. Davydov A.D., Erokhina O.O., Ryaboshuk S.V., Kovalev P.V. Analysis of the causes of cracks in the production of ingots and forgings from austenitic stainless steel 08Х18Н10Т (AISI 321). Key Engineering Materials, 2020, vol. 854, pp. 16–22.
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