Effect of Structure and Texture on Failure of Pipe Steel Sheets produced by TMCP

The method of orientation microscopy (EBSD) is used to study the structure and texture of low-carbon, low-alloy pipe steel sheets processed by controlled thermomechanical processing (TMCP). The temperatures of isothermal hot rolling varied. Samples cut from sheets showed a different fracture tendency during mechanical testing. The formation of cleavages (secondary cracks) during failure of steel is related to the presence of ferrite grains with orientation {001} <110> extended in the hot rolling direction. The formation of grains is a consequence of the isothermal hot rolling below the temperature

Features of microstructure, phase composition and strengthening capability of stainless steels with 13 – 17 % Cr

The paper considers the study of the features of structure and phase transformations in high-strength, resistant to carbon dioxide corrosion, complex alloyed steels of martensitic, austenitic-martensitic and martensitic-ferritic classes with 13 – 17 % Cr. Influence of the alloying on crystallization and solid state phase transformations was revealed in the temperature range of hot deformation and heat treatment using thermodynamic modeling and experimental study. The effect of quenching temperature on the phase composition and microstructure was analyzed as a result of X-ray diffraction phase analysis, optical and transmission electron microscopy. It was found that increase of nickel content leads to growth of retained austenite fraction resulting in significant decrease of yield strength along with high tensile strength and elongation. To obtain predominantly martensitic microstructure in martensitic-austenitic steel, the multistage heat treatment is proposed including quenching, intermediate annealing for precipitation of dispersed carbides and tempering forming final mechanical properties. The composition of precipitated carbides was evaluated by X-ray microanalysis. The results of the tensile test for steels with martensitic and martensitic-ferritic microstructure showed that required strength grade (σ0.65 ≥ 862 MPa; σв ≥ 931 MPa) was reached after heat treatment including quenching and tempering. Multistage heat treatment including quenching, intermediate annealing and final tempering was resulted in required strength properties of high-nickel martensitic-austenitic steel with 15 % Cr. © 2022 National University of Science and Technology MISIS. All rights reserved.Ural Federal University, UrFUThe authors express their gratitude to Khatkevich V.M. and Arsenkin A.M. for assistance in electron microscopy analysis (LLC “TMK STC”), as well as Mikhailov S.B. for assistance in conducting a dilatometric study (UrFU)

Structure and Properties of OCTG Pipe Cr–Mo Steel inTended for Operating in Sour Environment

При выполнении работы использовано оборудование ЦКП «Пластометрия».The paper presents the results of the study of microstructure, mechanical and corrosion properties of the economically alloyed Fe–Cr–Mo steel, designed for the production of OCTG to which the requirements are to provide increased strength and resistance to sulfide stress cracking (SSC) at the same time. The parameters that could be used for non-destructive testing methods developing to estimate the current state of structural elements during the operation conditions were established.Представлены результаты исследования структуры, механических, магнитных свойств экономнолегированной стали для нефтегазопромысловых труб, к которым предъявляются требования обеспечения повышенной прочности и стойкости к сульфидному растрескиванию под напряжением (СНР). Установлены параметры, которые в дальнейшем могут быть использованы при разработке методик неразрушающей диагностики состояния элементов конструкций из подобных материалов в процессе эксплуатации.Исследования выполнены в рамках работы по стипендии Президента РФ молодым ученым и аспирантам СП-150.2018.1