Vol. 25 No. 4 2023 3 EDITORIAL COUNCIL EDITORIAL BOARD EDITOR-IN-CHIEF: Anatoliy A. Bataev, D.Sc. (Engineering), Professor, Rector, Novosibirsk State Technical University, Novosibirsk, Russian Federation DEPUTIES EDITOR-IN-CHIEF: Vladimir V. Ivancivsky, D.Sc. (Engineering), Associate Professor, Department of Industrial Machinery Design, Novosibirsk State Technical University, Novosibirsk, Russian Federation Vadim Y. Skeeba, Ph.D. (Engineering), Associate Professor, Department of Industrial Machinery Design, Novosibirsk State Technical University, Novosibirsk, Russian Federation Editor of the English translation: Elena A. Lozhkina, Ph.D. (Engineering), Department of Material Science in Mechanical Engineering, Novosibirsk State Technical University, Novosibirsk, Russian Federation The journal is issued since 1999 Publication frequency – 4 numbers a year Data on the journal are published in «Ulrich's Periodical Directory» Journal “Obrabotka Metallov” (“Metal Working and Material Science”) has been Indexed in Clarivate Analytics Services. Novosibirsk State Technical University, Prospekt K. Marksa, 20, Novosibirsk, 630073, Russia Tel.: +7 (383) 346-17-75 http://journals.nstu.ru/obrabotka_metallov E-mail: metal_working@mail.ru; metal_working@corp.nstu.ru Journal “Obrabotka Metallov – Metal Working and Material Science” is indexed in the world's largest abstracting bibliographic and scientometric databases Web of Science and Scopus. Journal “Obrabotka Metallov” (“Metal Working & Material Science”) has entered into an electronic licensing relationship with EBSCO Publishing, the world's leading aggregator of full text journals, magazines and eBooks. The full text of JOURNAL can be found in the EBSCOhost™ databases.
OBRABOTKAMETALLOV Vol. 25 No. 4 2023 4 EDITORIAL COUNCIL EDITORIAL COUNCIL CHAIRMAN: Nikolai V. Pustovoy, D.Sc. (Engineering), Professor, President, Novosibirsk State Technical University, Novosibirsk, Russian Federation MEMBERS: The Federative Republic of Brazil: Alberto Moreira Jorge Junior, Dr.-Ing., Full Professor; Federal University of São Carlos, São Carlos The Federal Republic of Germany: Moniko Greif, Dr.-Ing., Professor, Hochschule RheinMain University of Applied Sciences, Russelsheim Florian Nürnberger, Dr.-Ing., Chief Engineer and Head of the Department “Technology of Materials”, Leibniz Universität Hannover, Garbsen; Thomas Hassel, Dr.-Ing., Head of Underwater Technology Center Hanover, Leibniz Universität Hannover, Garbsen The Spain: Andrey L. Chuvilin, Ph.D. (Physics and Mathematics), Ikerbasque Research Professor, Head of Electron Microscopy Laboratory “CIC nanoGUNE”, San Sebastian The Republic of Belarus: Fyodor I. Panteleenko, D.Sc. (Engineering), Professor, First Vice-Rector, Corresponding Member of National Academy of Sciences of Belarus, Belarusian National Technical University, Minsk The Ukraine: Sergiy V. Kovalevskyy, D.Sc. (Engineering), Professor, Vice Rector for Research and Academic Aff airs, Donbass State Engineering Academy, Kramatorsk The Russian Federation: Vladimir G. Atapin, D.Sc. (Engineering), Professor, Novosibirsk State Technical University, Novosibirsk; Victor P. Balkov, Deputy general director, Research and Development Tooling Institute “VNIIINSTRUMENT”, Moscow; Vladimir A. Bataev, D.Sc. (Engineering), Professor, Novosibirsk State Technical University, Novosibirsk; Vladimir G. Burov, D.Sc. (Engineering), Professor, Novosibirsk State Technical University, Novosibirsk; Aleksandr N. Korotkov, D.Sc. (Engineering), Professor, Kuzbass State Technical University, Kemerovo; Dmitry V. Lobanov, D.Sc. (Engineering), Associate Professor, I.N. Ulianov Chuvash State University, Cheboksary; Aleksey V. Makarov, D.Sc. (Engineering), Corresponding Member of RAS, Head of division, Head of laboratory (Laboratory of Mechanical Properties) M.N. Miheev Institute of Metal Physics, Russian Academy of Sciences (Ural Branch), Yekaterinburg; Aleksandr G. Ovcharenko, D.Sc. (Engineering), Professor, Biysk Technological Institute, Biysk; Yuriy N. Saraev, D.Sc. (Engineering), Professor, Institute of Strength Physics and Materials Science, Russian Academy of Sciences (Siberian Branch), Tomsk; Alexander S. Yanyushkin, D.Sc. (Engineering), Professor, I.N. Ulianov Chuvash State University, Cheboksary
Vol. 25 No. 4 2023 5 CONTENTS OBRABOTKAMETALLOV TECHNOLOGY Akintseva A.V., Pereverzev P.P. Modeling the interrelation of the cutting force with the cutting depth and the volumes of the metal being removed by single grains in fl at grinding........................................................................................................................................ 6 Sharma S.S., Joshi A., Rajpoot Y.S. A systematic review of processing techniques for cellular metallic foam production................. 22 Karlina Yu.I., Kononenko R.V., Ivantsivsky V.V., Popov M.A., Deryugin F.F., Byankin V.E. Review of modern requirements for welding of pipe high-strength low-alloy steels.......................................................................................................................................... 36 Startsev E.A., Bakhmatov P.V. The infl uence of automatic arc welding modes on the geometric parameters of the seam of butt joints made of low-carbon steel, made using experimental fl ux......................................................................................................................... 61 Martyushev N.V., Kozlov V.N., Qi M., Baginskiy A.G., Han Z., Bovkun A.S. Milling martensitic steel blanks obtained using additive technologies................................................................................................................................................................................ 74 Loginov Yu.N., Zamaraeva Yu.V. Evaluation of the bars’ multichannel angular pressing scheme and its potential application in practice................................................................................................................................................................................................... 90 EQUIPMENT. INSTRUMENTS Rajpoot Y.S., SharmaA.K., Mishra V.N., Saxena K., Deepak D., Sharma S.S. Eff ect of tool pin profi le on the tensile characteristics of friction stir welded joints of AA8011.................................................................................................................................................... 105 Chinchanikar S., Gadge M.G. Performance modeling and multi-objective optimization during turning AISI 304 stainless steel using coated and coated-microblasted tools........................................................................................................................................................ 117 Ghule G.S., Sanap S., Chinchanikar S. Ultrasonic vibration-assisted hard turning of AISI 52100 steel: comparative evaluation and modeling using dimensional analysis........................................................................................................................................................ 136 Pivkin P.M., Ershov A.A., Mironov N.E., Nadykto A.B. Infl uence of the shape of the toroidal fl ank surface on the cutting wedge angles and mechanical stresses along the drill cutting edge...................................................................................................................... 151 MATERIAL SCIENCE Sokolov R.A., Muratov K.R., Venediktov A.N., Mamadaliev R.A. Infl uence of internal stresses on the intensity of corrosion processes in structural steel....................................................................................................................................................................... 167 Klimenov V.A., Kolubaev E.A., Han Z., Chumaevskii A.V., Dvilis E.S., Strelkova I.L., Drobyaz E.A., Yaremenko O.B., Kuranov A.E. Elastic modulus and hardness of Ti alloy obtained by wire-feed electron-beam additive manufacturing................... 180 Vorontsov A.V., Filippov A.V., Shamarin N.N., Moskvichev E.N., Novitskaya O.S., Knyazhev E.O., Denisova Yu.A., Leonov A.A., Denisov V.V. In situ crystal lattice analysis of nitride single-component and multilayer ZrN/CrN coatings in the process of thermal cycling.......................................................................................................................................................................................... 202 Rubtsov V.E., Panfi lov A.O., Kniazhev E.O., Nikolaeva A.V., Cheremnov A.M., Gusarova A.V., Beloborodov V.A., Chumaevskii A.V., Grinenko A.V., Kolubaev E.A. Infl uence of high-energy impact during plasma cutting on the structure and properties of surface layers of aluminum and titanium alloys................................................................................................................... 216 Bobylyov E.E., Storojenko I.D., Matorin A.A., Marchenko V.D. Features of the formation of Ni-Cr coatings obtained by diff usion alloying from low-melting liquid metal solutions..................................................................................................................................... 232 Burkov А.А., Konevtsov L.А., Dvornik М.И., Nikolenko S.V., Kulik M.A. Formation and investigation of the properties of FeWCrMoBC metallic glass coatings on carbon steel.......................................................................................................................... 244 Sharma S.S., Khatri R., Joshi A. A synergistic approach to the development of lightweight aluminium-based porous metallic foam using stir casting method........................................................................................................................................................................... 255 Strokach E.A., Kozhevnikov G.D., Pozhidaev A.A., Dobrovolsky S.V. Numerical study of titanium alloy high-velocity solid particle erosion.......................................................................................................................................................................................... 268 EDITORIALMATERIALS 284 FOUNDERS MATERIALS 295 CONTENTS
OBRABOTKAMETALLOV Vol. 25 No. 4 2023 technology Review of modern requirements for welding of pipe high-strength low-alloy steels Yulia Karlina 1, a, *, Roman Kononenko 2, b, Vladimir Ivancivsky 3, c, Maksim Popov 2, d, Fedor Deriugin 2, e, Vladislav Byankin 2, f 1 National Research Moscow State University of Civil Engineering, 26 Yaroslavskoe Shosse, Moscow, 129337, Russian Federation 2 Irkutsk National Research Technical University, 83 Lermontova str., Irkutsk, 664074, Russian Federation 3 Novosibirsk State Technical University, 20 Prospekt K. Marksa, Novosibirsk, 630073, Russian Federation a https://orcid.org/0000-0001-6519-561X, jul.karlina@gmail.com; b https://orcid.org/0009-0001-5900-065X, istu_politeh@mail.ru; c https://orcid.org/0000-0001-9244-225X, ivancivskij@corp.nstu.ru; d https://orcid.org/0000-0003-2387-9620, popovma.kvantum@gmail.com; e https://orcid.org/0009-0004-4677-3970, deryugin040301@yandex.ru; f https://orcid.org/0009-0007-0488-2724, borck3420@gmail.com Obrabotka metallov - Metal Working and Material Science Journal homepage: http://journals.nstu.ru/obrabotka_metallov Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science. 2023 vol. 25 no. 4 pp. 36–60 ISSN: 1994-6309 (print) / 2541-819X (online) DOI: 10.17212/1994-6309-2023-25.4-36-60 ART I CLE I NFO Article history: Received: 13 September 2023 Revised: 21 September 2023 Accepted: 27 September 2023 Available online: 15 December 2023 Keywords: Steel Ferrite Perlite Beinite Martensite Impact toughness Fracture Hybrid laser welding Standards Acknowledgements Research was partially conducted at core facility “Structure, mechanical and physical properties of materials”. ABSTRACT For many years, proven arc welding processes have been used to weld large pipes of oil and gas pipelines, the scope of which extends from manual arc welding with stick electrodes to the use of metal orbital welding machines. Introduction reflects that the creation of new steel compositions for oil and gas pipelines is an urgent task to ensure its high reliability. Research Methods. Low-carbon steels with ferrite-perlite structure are usually used in pipe production, but these steels are unable to meet the increased market demands. New grades of steel with bainitic structure are appearing. Results. The failure of welded joints of pipelines made of high-quality steel is becoming a serious problem for the pipeline industry. Discussion. This paper analyzes the characteristics of weld microstructure and its relationship with impact toughness. The prediction of impact toughness based on the microstructural characteristics of weld-seam metals is complicated due to a large number of parameters involved. The common practice linking this property to the microstructure of the last roll of a multi-pass weld turned out to be unsatisfactory because the amount of needle ferrite, the most desirable component, may not always be the main factor affecting the impact toughness. The present review reports on the most representative study regarding the microstructural factor in the welded seam of pipe steels. It includes a summary of the most important process variables, material properties, normative rule, as well as microstructure characteristics and mechanical properties of the joints. Conclusion. It is intended that this review will help readers with different backgrounds, from non-specialist welders or material scientists to specialists in various industrial applications and researchers. For citation: Karlina Yu.I., Kononenko R.V., Ivancivsky V.V., Popov M.A., Derjugin F.F., Byankin V.E. Review of modern requirements for welding of pipe high-strength low-alloy steels. Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science, 2023, vol. 25, no. 4, pp. 36–60. DOI: 10.17212/1994-6309-2023-25.4-36-60. (In Russian). ______ * Corresponding author Karlina Yulia I., Ph.D. (Engineering), Research Associate National Research Moscow State Construction University, Yaroslavskoe shosse, 26, 129337, Moscow, Russian Federation Tel.: +7 (914) 879-85-05, e-mail: jul.karlina@gmail.com Introduction Due to the growing demand for oil and gas, pipelines made of high-quality steel are widely used in the pipeline industry. The material from which these pipes are made meets strict design requirements to withstand severe operating and environmental conditions [1, 2].
OBRABOTKAMETALLOV technology Vol. 25 No. 4 2023 The most common materials naturally chosen by pipe manufacturers are steel alloys due to its sufficient mechanical reliability and economic feasibility. Specifications concerning the chemical composition, mechanical properties and other important aspects such as welding, cutting, production, etc. of materials for oil and gas pipelines are determined by the American Petroleum Institute (API) [3], the International Organization for Standardization (ISO) and other national agencies [3-5]. API standards are commonly used by many national agencies as a reference to establish its own specifications for these materials. API specifications are accepted and widely used all over the world. In accordance with API requirements, pipeline materials are manufactured or supplied with product specification requirements: PSL 1 and PSL 2. The PSL 1 document contains only recommendations for the carbon equivalent; there are no restrictions on the impact strength, yield strength and ultimate strength. The PSL 2 document already prescribes mandatory values in a certain range for carbon equivalent, impact strength, yield strength and ultimate strength. Another significant difference is based on the type of pipe ends [1–3]. Knowledge of the chemical composition and mechanical properties of these pipes is necessary to understand the weldability and other aspects of welding these pipes. Pipe steels from different manufacturers that meet the requirements for strength and ductility [1–5] may have different microstructures [1–3, 10–34]. The most common steels are those with ferrite-perlite or ferrite-bainite microstructure [10–33]. Pipes can be made in two traditional ways: cold stamping (UOE: Upressing, O-pressing, and expanding) and seamless [3]. The production of pipes by cold stamping (UOE) tends to introduce intense deformation gradients into the sheet in different directions relative to a fixed orthogonal coordinate system during forming, with more serious gradients occur in the transverse direction [1, 2]. This affects not only the yield strength, but also the deformation hardening and subsequent instability (neck formation), which, finally, are the driving forces of the initiation and propagation of fracture. On the other hand, the production process of seamless pipes makes it possible to obtain a product with improved mechanical properties due to heat treatment, which removes residual stresses and reduces the out-of-roundness of the final shape. Consequently, it is expected that the mechanical properties of the final product will be uniform in space and direction [1, 2, 10]. Regardless of the method of pipes production, later during the construction of the pipeline pipes are connected to each other by welding. In recent decades, many studies of annular welds of onshore and offshore pipelines with cracks under operational load have been carried out [11, 12]. Cracks in the cup welds of pipelines made of high-quality steel are mainly located on the fusion line of the root material and in the heat-affected zone [13]. At the same time, cup welds have zones of material with different properties, such as base metal (BM), weld material (WM), root material (RM) and heat affected zone (HAZ). The heterogeneity of welded joints in geometry and material properties leads to a significant concentration of stresses and deformations in defective parts, which significantly reduces the deformation bearing capacity of welded pipe joints [13, 14]. During the welding process, the metal being welded heats is heated, the filler wire melts and a weld with a cast structure is formed, which has a transition zone to the base metal structure (HAZ). It is in this zone that the impact strength values decrease [14–20]. Due to the fast-flowing process of heating and melting of metal in the weld zone and the adjacent area of the base metal, HAZ structure with different sizes of austenitic grains is formed, with metal sections heated above and below the points Aс1 and Aс3. All this leads to a decrease in the mechanical properties of the metal. Consequently, considerable efforts to study high-strength steels for pipelines have been focused on increasing the impact strength in the heat-affected zone. The relationship between microstructure and impact strength for metals of multiple passes is very complex, since various factors can have beneficial and adverse effects depending on the material under study and its microstructural state. In addition to microstructural components, the influence of reheating, the presence of microphases and inclusions are recognized as critical factors affecting the microstructure and, consequently, the impact strength. Although little research has been conducted on the microstructure characterization of weld metals due to the aforementioned complexity, knowledge of the microstructure characteristics is critical for predicting impact strength. Thus, a more systematic study is fundamental to uncover this relationship between microstructure and strength.
OBRABOTKAMETALLOV Vol. 25 No. 4 2023 technology This review is devoted to the analysis of works related to the evaluation of the influence of the microstructure of the weld on the impact strength, as an indicator of the sensitivity of hot-rolled pipeline steels to brittle fracture. Steels for the pipes production The influence of the development of production technology and micro-alloying of pipeline steel on the strength is shown in fig. 1. Low-carbon alloy steels with ferrite-pearlite structure are widely used in pipe production [27]. Fig. 1. Effect of development of production technology and microalloying of pipeline steel on strength Increasing strength is a constant goal of the development of metallurgical alloys; currently more attention is paid to improving other important characteristics, such as toughness and weldability, each of which is negatively affected by the carbon content in steel. High-strength low-alloy (HSLA) or micro-alloyed (MA) steels, as it was later called [21–25], were already used at the beginning of the 20th century [23, 24]. Lowalloy steels, a much earlier defined class of steels than MA steels, are generally considered to contain less than 3.5 wt. % of all alloying elements and include Cr (0.5–2.5 %), Mo ≤ 3 % and V ≈ 1 %. High-strength low-alloy (HSLA) steels and the paradigm of microalloyed (MA) steels suggest that carbon may not be the best alloying element for making good steel [21–25]. In this context, HSLA steels show lower carbon content, which improves weldability and formability, but lower mechanical properties resulting from lower C content, which can be improved by the addition of alloying elements such as Nb, Mo and Ti, and an appropriate thermal and mechanical treatment. Each of these elements affects different mechanisms. On the one hand, many studies agree that Nb is capable of causing the accumulation of deformation in austenite before transformation, providing significant microstructure refining [1–3, 26–28]. Mo, in addition to the effect of solute resistance on the static kinetics of recrystallization, enhances the formation of complex non-polygonal transformation products [27, 28]. These strategies pursue finer final microstructures, which will result in a better combination of strength and toughness. On the other hand, Ti and Mo microalloyed steels have an interesting combination of high strength and good formability due to the wide dispersion of nanometer-sized titanium carbides in a thin matrix [21–23].
OBRABOTKAMETALLOV technology Vol. 25 No. 4 2023 HSLA steels usually contain very low carbon content and a small amount of alloying elements [1, 2, 14], and are classified by the American Petroleum Institute (API) in order of its strength (X-42, X-46, X-52, X-56, X-60, X-65, X-70, X-80, X-100 and X-120). These properties are achieved by careful selection of Miroslav’s composition and optimization of thermal and mechanical treatment (TMT) and accelerated cooling conditions after TMT. Specifications concerning chemical composition, mechanical properties and other important aspects such as welding, cutting, manufacturing, etc. of oil and gas piping materials are determined by the American Petroleum Institute (API), the International Organization for Standardization (ISO) and other national agencies [4–9]. Requirements for pipe steel of strength class K55 according to GOST R 53366-2009 The chemical composition (table 1) of steels is limited only by the content of harmful impurities – the content of sulfur and phosphorus should be no more than 0.030 wt. % (P ≤ 0.030, S ≤ 0.030). In addition, when tested in tension, steels should have a yield strength (σy) equal to 379–552 MPa and an ultimate strength (σu) above or equal to 655 MPa (table 2). Requirements for pipe steel of strength class K55 According to API requirements, piping materials are manufactured or supplied with two levels of product specification, known as PSL 1 and PSL 2. According to API 5L specification, PSL 1 pipes are supplied with grades A25, A25P, A, B, X42, X46, X52, X56, X60, X65 and X70, while PSL 2 pipes are supplied with grades B, X42, X46, X52, X56, X60, X65, X70, X80, X90, X100 and X120. It is also worth noting that there is no carbon equivalent limit for PSL 1 pipes. Another significant difference is based on the type of pipe ends. PSL 1 pipes can be manufactured and supplied with smooth ends, threaded ends, sockets and as a special connecting pipe, whereas PSL 2 pipes are manufactured only with smooth ends. In this document, information on the chemical composition, mechanical properties and the pipe manufacturing technologies used is indicated for pipe steel from X42 to X120. The original grades A25, A25P, A and B are excluded from the main discussion, since these grades are considered medium-strength materials. According to the American Society of Metals (ASM), low-alloy steel with a yield strength of at least 290 MPa is considered a high-strength steel. Knowledge of the chemical composition and mechanical properties of these pipes is necessary to understand the weldability and other aspects of welding these pipes. Requirements for chemical composition according to API 5CT are limited only to the content of harmful impurities – the content of sulfur and phosphorus should be no more than 0.030 wt. % (P ≤ 0.030, S ≤ 0.030). The difference in chemical composition requirements between PSL 1 and PSL 2 is shown in table 3. Ta b l e 1 Chemical composition of pipelines steel according to GOST R 53366-2009 (p. 71, Table 5) Class Strength Group type Mass content of element, % C Mn Mo Cr Ni Cu P S Si min max min max min max min max min max min max min 1 H40 – – – – – – – – – – – 0.030 0.030 – J55 – – – – – – – – – – – 0.030 0.030 – K55 – – – – – – – – – – – 0.030 0.030 – K72 – – – – – – – – – – – 0.030 0.030 – N80 1 – – – – – – – – – – 0.030 0.030 – N80 Q – – – – – – – – – – 0.030 0.030 –
OBRABOTKAMETALLOV Vol. 25 No. 4 2023 technology Ta b l e 2 Requirements for mechanical properties of steel for pipelines according to GOST R 53366-2009 (p. 72, Table 6) Class Strength Group Type Total elongation under load, % Yield strength Ri, MPa Strength Rn, MPa, min. Maximum hardness Back wall t hickness t, mm Permissible hardness variation HRC min max HRC HBW 1 H40 – 0.5 276 552 414 – – – – J55 – 0.5 379 552 517 – – – – K55 – 0.5 379 552 655 – – – – K72 – 0.5 491 – 687 – – – – N80 1 0.5 552 758 689 – – – – N80 Q 0.5 552 758 689 – – – – 2 M65 – 0.5 448 586 586 22 235 – – L80 1 0.5 552 655 655 23 241 – – L80 9Cr 0.5 552 655 655 23 241 – – L80 13Cr 0.5 552 655 655 23 241 – – Ta b l e 3 Differences between PSL 1 and PSL 2 pipe materials depending on its chemical composition Chemistry PSL 1 (wt. %) PSL 2 (wt. %) Maximum Carbon content for seamless pipes 0.28 % for ratings ≥ B 0.24 % Maximum Carbon content welded pipes Maximum 0.22 % Maximum Manganese content for seamless pipes 1.40 % for classes ≥ X46 1.40 % for classes ≥ X46 Maximum Manganese content welded pipes 1.40 % for stamps ≥ X46 and ≤ X60; 1.45 % for X65; and 1.65 % for X70 1.40 % for stamps ≥ X46 and ≤ X60; 1.45 % for X65; 1.65 % for Х70; и 1.85 % for X80 Maximum Phosphorus 0.030 % for ratings ≥ A 0.025 % Maximum Sulfur 0.03 % 0.02 % Weldability of pipe steels An additional criterion for pipe steels is the quantitative value of the carbon equivalent. The term “carbon equivalent” (CE) is used to refer to the hardenability or tendency to crack of a steel weld. CE helps to evaluate the cumulative effect of all important alloying elements on the microstructure (formation of the martensitic structure) during welding of steel, since it is the change in the microstructure of steel that determines its properties and behavior after welding. Therefore, a lower CE value is always preferable, which indicates good weldability. The American Petroleum Institute has adopted two equations (CEIIW and CE Pcm) to determine the carbon equivalent limit for API PSL 2 grade pipe steel. The CEIIW equation
OBRABOTKAMETALLOV technology Vol. 25 No. 4 2023 is provided by the International Welding Institute and is commonly used for simple carbon and carbonmanganese steels. In Europe, Pcm, the critical parameter of the metal, denoted by Pcm, is calculated. CE Pcm is taken from the documents of the Japanese Society of Welding Engineers. CE Pcm was proposed specifically to test the weldability of high-strength steels. + + = + + + + + + % % % % % % % % 5 ; 30 20 60 15 10 cm Si Mn Cu Cr Ni Mo V P C B + + + = + + + % % % % % % % . 6 5 15 IIW Mn Cr Mo V Cu Ni CE C The API piping specification states that CEIIW restrictions will be taken into account if the mass fraction of carbon exceeds 0.12 %. CE Pcm is used when the mass fraction of carbon in steel is less than or equal to 0.12 % (American Petroleum Institute, 2012). In addition to metal alloying, thermal cycles play an important role in changing the microstructure, as well as cooling rates during welding. Before predicting the behavior of steel during and after welding, it is also necessary to take into account the welding materials used and the conditions for preparing and conducting the welding process. The requirements of API 5CT for pipe steels for mechanical properties during tensile testing are shown in table 4. API 5CT requirements for pipe steels of a strength group K55 for mechanical properties during tensile testing are as follows: σy = 379–552 MPa, σu ≥ 655 MPa, minimum elongation, е, expressed as a percentage, should be determined by the following equation: = 0,2 0,9 A e k U , Ta b l e 4 API 5CT requirements for pipe steels for mechanical properties in tensile tests Pipe grade Minimum yield strength, MPa Maximum yield strength, MPa Minimum ultimate tensile strength, MPa Maximum ultimate tensile strength, MPa Х42 290 496 414 758 Х46 317 524 434 758 Х52 359 531 455 758 Х56 386 544 490 758 Х60 414 565 517 758 Х65 448 600 531 758 Х70 483 621 565 758 Х80 552 690 621 827 Х90 625 775 695 915 Х100 690 840 760 990 Х120 830 1,050 915 1,145
OBRABOTKAMETALLOV Vol. 25 No. 4 2023 technology where e is the minimum elongation within the estimated length of 50.8 mm (2 in) as a percentage, rounded up to 0.5 percent when it is less than 10 % and up to one percent when it is 10 % or higher; k is a constant equal to 1942.57 (625,000 when calculated in inches); A is the cross-sectional area of the tensile test specimen in mm2 (in2), based on the specified outer diameter or nominal width of the specimen and the specified wall thickness, rounded to an accuracy of 10 mm2 (0.01 in2) or 490 mm2 (0.75 in2) (whichever is less); U is the minimum specified tensile strength in MPa (psi). Impact strength requirements In accordance with API 5CT [3], the impact test is carried out using the Charpy method for V-notched specimens. The requirements for the absorbed impact energy of the tested specimens (at least 3 pieces) should be: – for transverse specimens KV+21 ≥ 20 J; – for longitudinal specimens KV+21 ≥ 27 J. The result less than the required absorbed energy can be obtained on no more than one specimen, and the absorbed energy value should be less than two-thirds of the required. The permissible dimensions of the impact test specimens and the reduction coefficients of the absorbed impact energy are presented in the standards (table 6). Requirements for heat treatment The API 5CT standard does not contain specific requirements for the heat treatment of pipes of strength class K55, it is allowed to be supplied in a state after normalization, normalization with subsequent tempering or after quenching and tempering along the entire length and throughout the pipe body at the manufacturer’s choice or in accordance with the requirements of the supply contract. However, the weld of electric-welded pipes should be heat-treated after welding at a temperature not lower than 540 °C (1,000 °F) or treated in such a way that there is no untempered martensite. This is due to the requirements for testing pipes for crumpling. Production of pipes for oil and gas pipelines Currently, two main technologies are used for the production of rolled products for large diameter pipes: controlled rolling followed by air cooling and controlled rolling followed by accelerated cooling. The basic concept of thermal and mechanical treatment (TMT) or thermal and mechanical controlled treatment (TMCT) underlies the development of many advanced steel grades with improved mechanical properties over the past 50 years. At TMCT, cooling rates and deformation models affect the heterogeneity of the microstructure and crystallographic texture of thick-walled rolled plates. It led to heterogeneity of the mechanical behavior in thickness and affected the properties of the plate. An increase in the thickness of the steel plate leads to significant differences in the plastic ability of the material to deform in the direction of thickness at different stages of forming [1–3]. Tests of the mechanical properties of thick-walled pipeline steel K60 at TMCT demonstrated these differences in thickness [1, 2]. Thick-walled steel plate K60 undergoes a longer holding time in thickness near the center during rapid cooling; cooling occurs at a lower rate and promotes grain growth [8–13]. On the other hand, changes in the deformation mode also affect the microstructure along the thickness of the rolled metal. In the process of hot rolling, the surface layer undergoes severe shear deformation due to friction between the surface and the rolls, which leads to the appearance of many dislocations in the ferrite [10, 11]. Moving dislocations weave, forming new grain boundaries, as a result of which the initial ferrite grains break up into many subcrystals [13, 25, 26]. Crystal fragmentation leads to more significant deformation and an increase in the internal stored energy of the grain, contributing to the rapid formation of ferrite in the surface layer [25, 26]. This combination (rapid cooling and shear deformation) leads to a decrease in the grain size in the surface layer. Hardening during grain refining often improves mechanical properties. Reducing the grain size increases the plasticity of the surface layer, so that
OBRABOTKAMETALLOV technology Vol. 25 No. 4 2023 the finer ferrite provides better coordination of deformation, effectively preventing stress concentration. At the same time, grain refining effectively restricts the movement space of dislocations inside the ferrite along the surface layer, enhancing the interaction between dislocations and increasing strength [9, 11]. However, themechanical propertiesmanifested by themicrostructure can affect the degree of deformation hardening and the behavior of plastic damage during further forming of the pipe, which, in turn, affects the final pipes’ properties [1–4]. After the pipes are formed, the outer and inner layers of the pipes in the walls experience repeated tensile and compressive deformations, respectively [1–3]. Because of these different deformation histories, the flattened segment of pipe walls often exhibits unexpectedly much lower or higher yield strength than the sheet metal from which it is made. Many studies have shown that the yield strength of the material increases and the ductility decreases during production and that the deformation behavior varies depending on the microstructure [8, 31]. Therefore, when it is necessary to obtain a strength class of steel below K60, TMT is used, and if it is required to obtain rolled products with a strength above K60, TMCT is used. Many researchers recognize that with an increase in the pipe thickness over 27 mm, there are many unresolved issues in the pipe production process to obtain a homogeneous structure across the rolled section, and in the future during the subsequent production of the pipe by wall thickness during the forming process. API class pipes can be made both seamless and welded. The seamless process is a hot-working process used to form a pipe product without a weld. Welding processes used for the manufacture of API class pipes can be divided into welding processes without the use of filler metal (contact welding, electric welding and laser welding) and with the use of filler metal (submerged-melt welding and arc welding with a metal electrode). The manufacturing technology of steel pipes and pipes by conventional electric resistance welding (ERW) is shown in fig. 2. ERW steel pipe manufacturing procedures begin with a rolled steel sheet of the appropriate thickness and a certain width to form a pipe that meets certain specifications. The steel strip is stretched through a series of rollers, which gradually form a cylindrical tube. When the edges of the cylindrical plate meet, an electric charge is applied at the right points to heat the edges so that to be welded together. However, it is difficult to get good performance when using a conventional ERW process. The reason is that ERW steel pipes are made by cold rolling steel strap, and the ductility of steel pipes is inevitably inferior to the ductility of steel strap due to deformation hardening during cold rolling. In addition, the hardening caused by rapid cooling after welding has the same effect on the mechanical properties of the steel pipe in the welded joint. The processes used to produce two levels of product specification (PSL 1 and PSL 2) for HSLA pipe steels are presented in documents [4–9]. From the information presented above, we see that the production of pipes is a complex high-tech process, which at the output gives us an innovative high-quality product, which in the future should be welded in the field into a gas or oil pipeline. The analysis of works [21–28] shows that when forming a weld in steels of strength class K60 with a predominant structure of ferrite and perlite, it is impossible to obtain high values of strength and toughness at the same time. One of the promising directions for the development of high-strength pipe steels is the production of a crystalline ordered bainite structure [1, 2, 21–25], instead of ferrite-pearlite. It is shown in [26] that two generations of low-alloy steels (ferrite/perlite, and then bainite/martensite) have been developed over the past thirty years and have been widely used in structural applications. The third generation of low-alloy steels is expected to provide high strength, improved ductility and toughness, as well as meet new requirements for weight reduction, environmental friendliness and safety. This paper examines the recent progress in the development of low-alloy steels of the third generation with M3 microstructure, namely microstructures with multiphase, metastable austenite and multiscale separations. The review summarizes alloy designs and processing methods for microstructure control, as well as the mechanical properties of alloys. Special attention is paid to the stabilization of residual austenite in lowalloy steels. Then, multiscale nanowires are added, including carbides of microalloying elements and copper-enriched precipitates obtained in low-alloy steels of the third generation. The structure-properties
OBRABOTKAMETALLOV Vol. 25 No. 4 2023 technology Fig. 2. Technologies for manufacturing welded steel pipes (a) and conventional electric resistance welded (ERW) pipes (b) а b relationships of third-generation alloys are also discussed. Finally, the prospects and problems of future applications are studied. It isnoted in [27] that themost important phenomena in this context are themartensiticphase transformation and the associated effects of accommodation plasticity (TRIP) and twinning-induced plasticity (TWIP) that can occur, both of which are possible due to the presence of thermodynamically metastable austenite. The paper [28] provides an overview of the technology for manufacturing high-strength pipeline steels. The microstructure and mechanical properties of sheets and pipes made of steel grades X80, X100 and X120 are analyzed and discussed. The microstructure of steel X80 consists of needle ferrite containing the M/A phase (martensite/austenite component). The X80 steel sheets and pipes tested were found to exhibit superior performance in the Drop Weight Tensile Test (DWTT). The DWTT of 85 % SATT of X80 steel in the pipe was about -40 °C. The deformation capacity of the X80 pipeline was evaluated on a large-sized deforming machine operating under the load of bending and axial compression forces. The developed X80 pipeline was found to meet DNV and API bending resistance requirements. In the case of X100 steel, the main phase was bainitic ferrite, which has a lath and granular morphology, and M/A existed as the second phase. It was shown that the developed steel X100 can be implemented with the appropriate properties for UOE pipes. DWT 85 % SAT of steel pipe X00 was shown at temperatures below -40 °C. The development of pipeline steel of the X120 grade was also tested. The microstructure of steel X120 consists of bainitic ferrite and needle ferrite. The tensile strength of the developed steel sheets and pipes X120 fully meets the target properties required in the current study. The DWTT of 75 % SATT of the developed X120 sheet steel
OBRABOTKAMETALLOV technology Vol. 25 No. 4 2023 and pipe was below -30 °C. Bainitic ferrite, exhibiting a lath and granular morphology, was the main phase, and M/A existed as the second phase. Works [2, 11–18] note that when welding pipes made of steel X80, X100 and X120 grades in field conditions, difficulties arise in ensuring an optimal structure in the HAZ and a decrease in the mechanical properties of the weld metal. Welding technologies In the standard GOST 29273-92, a definition of weldability is given for all metal materials, taking into account all processes, various types of structures and whatever properties it should satisfy: “Definition of weldability. A metal material is considered to be weldable to a certain extent in these processes and for this purpose, when metal integrity is achieved by welding with an appropriate technological process so that the parts to be welded meet technical requirements, both in terms of its own qualities and in terms of its influence on the structure it forms.” According to AWS (American Welding Society), weldability is defined “the capacity of a material to be welded under the imposed fabrication conditions into a specific suitably designed structure and to perform satisfactorily in the intended service.” This concept, although unique, can be divided into three: operation weldability, metallurgical weldability and weldability during operation. Operation weldability is related to the operational conditions of welding, such as: the combination of the process and the nature of the base metal; welding position; welder skills; co-assembly methods, etc. Metallurgical weldability is associated with thermal and chemical conditions that can create defects or undesirable mechanical properties in the welded joint associated with metallurgical phenomena such as phase transformation, microsegregation, etc. Weldability during operation is more related to the service life of the component being welded. At this point, the main focus will be on metallurgical weldability. Metallurgical issues of steel pipe production are widely covered in the literature; however, the subsequent welding of pipes in the field makes its own adjustments to the operational efficiency of the entire pipeline. The main methods of pipe welding are: arc welding with a low hydrogen electrode, submerged metal automatic welding (SMAW), gas metal arc welding (GMAW), flux-cored arc welding (FCAW-S). The technological features of these methods and equipment are well covered in the literature. Let’s consider promising technologies [29–39]. Laser-arc hybrid welding (LAHW) and automatic welding equipment have been in the research, development and design stages since 2,000 [29–33]. In the laser-arc hybrid welding (LAHW) process, the laser beam and the electric arc interact in the welding bath, and its synergetic effect is used to perform deeper and narrower welds (fig. 3), increasing productivity [30–33]. This method has been successfully implemented in the laboratory when welding the root in all positions of linear pipes with a tip diameter of 8 mm, and the laser source and cooling system are under investigation for its in-situ applicability [29, 30]. In the review paper [32], data on the thickness of the materials being welded are given in table 5. The paper [33] presents industrial options for welding pipelines (fig. 4). In [30], the influence of the parameters of hybrid laser-arc welding: heat input and preheating on the cooling rate, microstructure and mechanical properties of the welded joint is investigated. Specimens made Fig. 3. Cross-section of welds joined by different welding methods: GMAW, LBW and LAHW [31]
OBRABOTKAMETALLOV Vol. 25 No. 4 2023 technology Ta b l e 5 Cross-sections of hybrid laser joints made of heavy gauge steel [32] A B C D E AH36 H1, T3 S355J2 H3, T3 S355J2 H3, T1 S355J2 H3, T2 SM490A H2+CW, T2 F G H I J API 5L X65 H2, T2 RQT701 H1, T3 AH36 H1, T2 High-strength H2,+ T4 API 5L X65 H2, T2 K L M N O API X65 H5, T3 API X65 H4, T3 API X65 H4, T3 S355 J2+N H0, T3 HSLA H2+CW, T3 P Q R S T S355J2+N H6, T4 P265GH H4, T3 Q235 H2, T2 S355 J2+N H0, T4 SM490A H2+CW, T3 U H0 – arc GMAW + laser H1 – arc GMAW + laser CO2 H2 – arc GMAW + fiber laser H3 – arc GMAW + disk laser H4 – arc SAW + disk laser H5 – arc SAW + laser CO2 H6 – GMAW + SAW T1 – OS_SP T2 – OS_MP T3 – DS_SP T4 – DS_MP S460 H5, T3 25 mm 25 mm 25 mm 25 mm 25 mm 28 mm 30 mm 30 mm 30 mm 32 mm 35 mm 35 mm 35 mm 40 mm 40 mm 40 mm 40 mm 40 mm 40 mm 50 mm 51 mm
OBRABOTKAMETALLOV technology Vol. 25 No. 4 2023 a b Fig. 4. Laboratory version of laser-arc hybrid technology (a) and field version for pipe welding (b) [33] of API 5L X80 steel with a root thickness of 14 mm were welded with MF 940 M welding wire. It is shown that a decrease in the cooling rate of welds from 588 °C/s to 152 °C/s reduces the hardness of the weld metal from 343 ± 12 HV to 276 ± 6 HV and the tensile strength from 1,019.5 ± 14 MPa to 828 ± 10 MPa, as well as an increase in the bainitic phase of the weld metal is revealed when increasing the preheating temperature to 180 °C and the maximum running energy. The work [31] notes that to develop oil and gas resources in deep-sea areas, it is necessary to lay a large number of underwater pipelines. J-lay is the primary method for laying deep undersea pipelines. Welding the circumferential seam in a horizontal-vertical position is a mandatory part of the J-lay method. Currently, the following sequence is usually used: hot pass welding of the root, filling and facing layers of the welded joints [31]. Due to problems with welding efficiency and quality, traditional welding methods could not meet the requirements of industrial pipelines with thicker pipe wall and larger pipe diameter, so there was an urgent need to develop a welding method with high efficiency and productivity, as well as a high degree of automation. The heat source characteristics of laser-MAG hybrid welding, which combines deep laser penetration and wide arc adaptability, make it very suitable for welding pipes with thicker walls [29– 34]. Compared to conventional welding in a horizontal-vertical position, it has the following advantages: deep penetration, high welding speed and high welding quality. The level of penetration with single-sided welding is the same as with other root welding methods + one fill pass. At the same time, it reduces spatter and welding distortion, reduces the need for back gouging, and improves production efficiency [29–32]. A lot of work has been carried out in the country and abroad to study the technology of hybrid laserMAG welding in the field of pipeline laying (for welding in a horizontal-vertical position) [34, 35]. The use of hybrid laser-MAG welding not only increases the speed and quality of welding, but also gives great advantages in reducing the sensitivity of butt joints and welding defects [34, 35]. Despite the significant progress of LAHW in technical implementation, research work on the structure and properties of metals, and taking into account the indisputable fact that this technology has a high penetrating power and efficiency; at this stage of development it is considered an industrial innovation. The technology and equipment need constant improvement in the process to meet the requirements of field welding. The transfer controlled MAG (TC) welding process is a derivative of the MAG process for root pass welding in pipelines. There are various patents for short circuit switching control [35]. Among them there is a control developed and patented by The Lincoln Electric Company under the trade name “STT® (Surface Tension Transfer) [35]. One of the variants of the MAG-TC welding process is to control the current without changing the electrode feed rate, using a special welding source for this, which ensures low welding energy, smoke and spatter. Reducing the spatter rate reduces the time required for cleaning both the burner and the welded joint [35]. The metal transfer obtained by this process is carried out by short-circuiting using pure CO2 or Ar/CO2 mixtures as a protective gas [35]. Fig. 5 shows the waveform used in the MAG-TC process.
OBRABOTKAMETALLOV Vol. 25 No. 4 2023 technology Fig. 5. Welding pulse shape with controlled transfer (TC) Unlike MAG process sources, MAG-TC process sources operate on a constant current curve rather than a constant voltage curve. Thus, the source is capable of changing the electric current of the arc in a short period of time. Arc stability is maintained even with changes in electrode length and welding angle due to precise control of the welding current. Thus, as in the MAG process, the change in current to adjust the electrode elongation is eliminated, ensuring that there is no point reduction in the heat transferred [35]. Point A in fig. 5, corresponds to the base current (from 50 to 100 A), which has the function of maintaining the arc open and transferring heat to the weld pool. When a drop formed at the tip of the electrode touches the molten pool, creating a short circuit (point B), a current drop occurs. At point C, the current of the pinch effect of the drop is applied, which has the function of separating the drop from the tip of the electrode and placing it in the melt pool. At point D, the electronic control device of the welding current source monitors the electrical parameters of the arc and determines when the liquid bridge between the molten drop and the tip of the wire is about to break, in order to then reduce the current to values from 45 to 50, ensuring the restoration of the electric arc. After restoration of the arc (point E), the peak current, the function of which is to press down on the molten pool to prevent short circuit and heat the connection. The function of the tail is to control the rate at which the peak current decreases to the base current, acting as a rough control of the welding energy. The advantages of using the MAG-TC process for pipe root welding compared to MAG welding are that short-circuit control prevents lack of fusion, heavy smoke and spatter even when using CO2 as a shielding gas, which ensures good surface finish and weld strength [35]. Compared with the TIG process, the MAGTC process has a welding speed 4 times higher [35]. Compared to the ER process, the MAG-TC process has advantages mainly in terms of increased productivity, since there is no need to stop welding to change consumables and grind after finishing the root pass, since, unlike the ER process, the weld profile is flat. The finishing profile of the root pass with cellulose wires is convex, which leads to large losses of time during the roller grinding operation [35]. Another promising option, from the point of view of reducing the cost of welding works and increasing productivity, is butt resistance welding of pipes (BRW), which significantly increases work productivity. However, the disadvantage of the technology is the non-standard cutting of edges. To solve this issue, a hybrid technology of combining resistance welding and flux-cored welding (FCW) methods is possible. With BRW, it is difficult to obtain high impact strength of the joint on specimens with a sharp notch (Charpy). To obtain the required impact strength indicators for welded joints of BRW pipes, it is recommended to perform an additional technological operation – local heat treatment of the welded joint. Friction stir welding (FSW) is in the research stage, being introduction into traditional pipeline welding technologies. X80 pipeline steel plates were friction stir welded (FSW) under cooling conditions of air, water, liquid CO2 + water and liquid CO2, resulting in defect-free welded seams [26]. The microstructural evolution and mechanical properties of these FSW joints were studied. It has been shown that the impact toughness of the metal in the HAZ is 20–60 % higher compared to traditional welding methods [26]. Welding features The weld is formed by crystallization of the melt of the weld pool, containing both the main and filler (when introduced) materials. Welding thermal cycles cause significant changes in the mechanical properties of the base material. It is well known that the weld metals of steel differ from most parent steels in that it has
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